Technical Information

1. Terminology of Taps Technical-1

2. Flutes Technical-2
3. Edge angle and Cutting allowance of taps Technical-3
4. Recommended Tapping Speeds Technical-4
5. Tapping Speed and Revolution Technical-5
6. Tapping Torque Technical-6
7. Metric Thread and Gauge Profile Technical-9
8. Length of engagement Technical-11
9. Classes of Internal Threads and Classes of Taps Technical-13
10. Guide to Thread Forming Taps(Roll Taps) Technical-18
11. How to set the tap’s oversize to meet with the coating margin of internal threads Technical-20
12. Recommended bored hole sizes Technical-21
13. Recommended Hole Sizes for Thread Forming Taps Technical-27
14. Bar diameter for external threads(for cutting type dies) Technical-28
15. Bar diameter of external screws(for thread rolling dies) Technical-31
16. Surface Treatment Technical-32
17. Carbide Taps Technical-35
18. Pipe Taps Standard Technical-37
19. Features of MC-Helical Thread Mills Technical-44
20. Selecting different tap holder combinations by machine feed system Technical-47
21 The common mechanics for a tap to cut oversize on an internal thread Technical-49
22. Trouble Shooting Technical-51
23. Center Drills Technical-55
24. Table of recommend centering condition Technical-56
25. Thread Series Technical-58
26. Basic profile of threads Technical-60
27. Symbols for Standard Threads Technical-62
28. Cross chart of thread cutting tool standard Technical-65
29. Hardness conversion table Technical-66
30. Conversion table from inch to millimeter Technical-67
31. Chemical Component table of work materials Technical-69
32. Materials used for Cutting Tools Technical-79
33. Design of taps and dies Technical-81
34. Design of center drills and centering tools Technical-83
35. Design of dies Technical-84
36. Design of taps for USA market and European market Technical-84
 Terminology of Taps
Description of products

Flute Width of land Chamfer angle

External center

Core dia. Internal center Shank dia.

Size of square

Chamfer length Thread length Shank length Length of square

Overall length

■Chamfer relief ■Thread relief and cutting angle

Width of margin

Chamfer relief
Thread relief

Heel
Indicator drop
for thread relief
Indicator drop
for chamfer relief

Cutting face Cutting angle

Edge angle, including chamfer relief, thread relief, cutting angle and others, and heat treatment, have important functions affecting on workpiece
shape, tool life, surface finish of internal screw thread, and so on.

■Chamfer of hand tap

Taper tap
Plug tap
Bottoming
tap Plug tap Taper tap Bottoming tap
Information
Technical

In general, tap chamfer is the most important part of taps to create internal thread. The function of full thread part of taps is to make a guidance.

Technical-1

650
 Flutes

■Major functions of flutes are :

Description of products
1) Chips' pocket, 2) lubricant supply route, 3) rake angle formation, 4) to determine cutting amount in relation to the number of chamfer threads. And
all are very important. Taps' flutes are classified into following groups by tapping methods, fluting method, tapping direction, and hand of screw
thread.

Straight Hand tap

Spiral Spiral fluted tap for blind hole

Cutting type

Left Hand Spiral Spiral fluted tap

for through hole

Spiral point Spiral pointed tap

Flutes of tap

with oil groove Roll tap

Forming type

without oil groove Roll tap

■Type of Flute
Type of Taps Type of Taps
Cutting type Forming type
Flute Flute
Straight Flute With oil groove

Spiral Flute

Spiral Point Without oil

Flute groove
Information
Technical

In general, the number of flutes for cutting type taps are usually increased as O.D. becomes larger. However, it is also influenced by tap's strength and regidity,
the accomodation of chip, the amount of cutting, and lubricant supply system.

Technical-2

651
 Edge angle and Cutting allowance of taps

■Cutting angle and Chamfer relief

Description of products

θ : Cutting angle γ : Chamfer relief

Chordal Hook Angle Rake Angle Tangential Hook Angle

γ γ γ

θ θ θ

Cutting angle of hook face. The angle between the Cutting angle of rake face. The angle between the Cutting angle of hook face. The angle between the
center line passing the cutting edge and the straight center line passing the cutting edge and the straight center line passing the cutting edge and the straight
line linking the cutting edge with the thread root. line linking the cutting edge with thread root. line tangent to the rake face on the cutting edge.

■Thread relief S : Thread relief

Concentric-unrelieved Con-eccentric thread relief Eccentric thread relief

(A)

(B)

No relief exists at land. Start (A) and heel (B) of Radial relief in the thread form starts at the back of Radial relief in the thread form starts at the cutting
thread land have same concentricy. a concentric margin. edge and continues to the heel.

■The amount of cut portion Land A

Please refer to the pictures shown.

In such taps as have 4 flutes and 3 thread chamfer, the Land D

cutting operation progresses in order from the edge of

A1, B1, C1, D1…A2, B2…A4. Tap end is usually smaller Land B
Land A
than the size of bored hole, and A1 may not make any
cutting operation.
Land C

Land B
t : Amount of cut portion per blade

Land C
Information
Technical

Land D

Tapping direction Bored hole diameter

Technical-3

652
 Recommended Tapping Speeds

■Tapping Speeds

Description of products
Following usage conditions affect tapping speeds : kind of taps, workpieces, number of chamfered threads, materials, hole condition and fluid. It is
necessary to select the suitable tapping speed by paying attention to these conditions.
When work material has excellent workability, when there is a little depth of tapping, or when tapping fluid can be sufficient, select rather higher
tapping speed. When workability of work material is unknown, to be safe, try nearly the lowest tapping speed at first, and then increase the speed
gradually.

Unit : m/min

Tapping Speed
Workpiece Materials
Spiral Fluted Spiral Pointed Roll Taps Straight Fluted Cemented Carbide

Low Carbon Steels

Medium Carbon Steels
High Carbon Steels
Alloy Steels
Heat treated Steels

Stainless Steels
Tool Steels
Cast Steels
Cast Irons
Ductile Cast Irons
Coppers
Brass · Brass Casting

Phosphor Bronze ·
Phosphor Bronze Casting
Wrought Aluminum
Aluminum Alloy Castings
Magnesium Alloy Castings
Zinc Alloy Diecastings

Thermosetting Plastic Bakelite (Phenol-PF)

Thermoplastic resin PVC, Nylon

Titanium Alloys

Nickel Base Alloys Hastelloy, Inconel, Waspaloy

■Formula

Tapping Speed (Vc) Revolution of tap (n)

n : Revolutionof tap (min-1) Vc : Tapping Speed (m/min)

: 3.14 Dc : Nominal dia. of tap (mm)
Information
Technical

Dc : Nominal dia. of tap (mm) : 3.14

Technical-4

653
 Tapping speed and Revolution
Description of products

■Conversion table
Tapping speed

Outside diameter of tap

Information
Technical

Technical-5

654
 Tapping Torque

Description of products
■Tapping Torque of Cutting type Taps

The torque starts increasing as the threads of chamfer enter the workpiece material. It becomes highest when all threads of chamfer cut into
workpiece material, and is in plateau until the chamfer cuts through the workpiece. After that, the torque will decrease until the end of tapping.

■Cutting Torque Line

Cutting torque lines in the test of different kinds of taps, hand tap, spiral fluted tap, spiral pointed tap are shown below.

Tapping Condition
Tap : HSS P2 M8×1.25 Bored hole size : 6.8mm
Cutting speed : 6.1m/min Cutting oil : Water insoluble oil
Workpiece material : S50C Machine : Drilling machine
Tapping type : 10mm Through hole Measurement equipment : Piezoelectric torque tester

Type of tap Torque lin es Description

Hand tap (P2) Taper tap
(9 threads)
Gentle slope is observed because of less cutting
by each cutting chamfer, but longer tapping
time is taken than in the other hand taps.

Plug tap
(5 threads)
Plateau is observed since whole chamfer threads
enter the workpiece material. Tapping time is
much shorter than that of the taper tap.

Bottoming tap
(1.5 threads) Plateu is also observed since whole short
chamfer threads enter the workpiece material.
Tapping process time is shorter than that of the
plug tap.

Spiral fluted tap (P2, 2.5 threads)

Spiral fluted tap pulls out the chips, good choice
for blind hole tapping. The cutting torque of
spiral fluted taps is smaller than that of the hand
taps.

Spiral pointed tap (P2, 5 threads)

Spiral pointed tap pushes out the chips forward.
It is good choice for through hole use. Cutting
torque is smallest in all taps.

The cutting torque will change depending on the kind of taps, cutting chamfer, number of flutes, workpiece materials and their hardness,
lubrication types, and chips.
Information
Technical

Technical-6

655
 Tapping Torque

■Comparison of Cutting Torque by Different Type of Taps

Description of products

Cutting torque of hand tap (HT), and spiral fluted tap (SP), and spiral pointed tap (PO) differs, shown in the chart below.

Tapping Condition
Tap : HSS P2 M10×1.5
Cutting speed : 10m/min
Workpiece material : S50C
Hole condition : 20mm through hole
Bored hole size : φ8.5, drill
Lubrication : Water insoluble oil

Machine : Radial drilling machine

Measurement equipment : Piezoelectric torque tester
Tapping Torque

If the cutting torque of hand tap is assumed as 100, the cutting

torque of other taps is as follows :

Hand Tap : 100

Spiral fluted Tap : 70~75
Spiral Pointed Tap : 60~65
HT (plug) SP (2.5 Pitches) PO (5 Pitches)

■Tapping Torque of Forming type Taps

■Calculation for Tapping Torque of Roll Taps

○It is hard to calculate tapping torque for roll taps because they contain more complicated factor than the cutting taps.
○According to our experience, tapping torque of roll taps is twice or three times larger than that of the cutting taps in general.
○Major factors increasing or decreasing tapping torque of roll taps are :
(1) Mechanical characteristic of workpiece (Tensile strength, hardness, spring back feature, work hardening index) : As the tensile strength gets
larger, the threading torque becomes larger.
(2) Size and length of bored hole: Bored hole size is usually defined to obtain 75% thread height of basic thread profile. Roll taps may be
shuttered due to the excessive tapping torque when the bored hole size is made smaller to obtain higher thread height. Tapping torque gets
larger as the efficient length of internal screw becomes longer because there is an increase in friction coefficient caused by spring back of
workpiece material.
(3) Tapping process (tapping speed, lubricant, and rigidity of main spindle).
(4) Surface treatment of taps (oxidizing, nitriding, TiN, and TiCN coatings).
Information
Technical

Technical-7

656
 Tapping Torque

○Tapping Torque Equation for Forming Taps

Description of products
Based on the tensile strength of workpiece material, we prepare following equation to obtain tapping torque of standard formig taps.
Condition : Effective length of internal screw is 1.5D,. Thread height is 75%.

Deforming resistance
Tapping Torque Equation for Forming Taps Workpiece Materials
(N/mm2)
General Structure Steels, Low Carbon Steels 750~850
Medium Carbon Steels, Alloy Steels 1150~1350
Stainless Steels 1100~1300
T : Tapping Torque (N-m) Wrought Aluminum 250~350
Dc : Nominal Diameter of Tap (mm)
P : Pitch (mm) Aluminum Die castings 380~530
Kf : Deforming resistance (Nmm2)
Coppers, Wrought Copper Alloys 750~1050

Information
Technical

Technical-8

657
 Metric Thread and Gauge Profile
Description of products

Relation of tolerance position between screw thread classes and thread gauge classes in ISO(new JIS) and old JIS
standard.

■External threads and Limit gauges for external threads

Example : ISO M10×1.5/6g and old JIS M10×1.5/Class 2
Basic Major Dia. of exterminal thread 10mm
*Relation of tolerance zone of external thread and
that of limit gauges for external thread is shown.
Class 2
*Pitch Dia. of external thread is virtual pitch Dia.
*Pitch Dia of screw ring gauge is simple pitch Dia.

Pitch diameter tolerance and Major diameter

tolerance of external thread
Tolerance of screw ring gauge and calliper gauge

Minimum wear

Basic Pitch Dia. of external thread 9.026mm

Class 2

Basic Profile
Class 2

Class 2

Max Truncation

Min Truncation

Min Minor Dia

Max Minor Dia

. Only pitch diameter is described.

NOT GO Inspection ring gauge
Solid NOT GO screw ring gauge

Solid GO screw ring gauge

NOT GO Working ring gauge

GO ring gauge (Both for working and inspection)

Tolerance zone Limit caliper Limit caliper

Plain NOT GO caliper gauge

Tolerance zone
for Major Dia. gauges for gauges for for Picth Dia.
Plain GO caliper gauge

of external Inspection. Working. of external

thread thread

Go Not Go Go Not Go

Gauge for Major Dia. of Extenal Thread Gauge for Pitch Dia. of Extenal Thread
Information
Technical

Technical-9

658
 Metric Thread and Gauge Profile

■Internal threads and Limit gauges for internal threads

Description of products
Example : ISO M10×1.5/6H and old JIS M10×1.5/Class 2
Gauge for Pitch Dia. of internal thread Gauge for Minor Dia. of Intenal Thread

Tolerance zone Toleramce zone

for Pitch Dia, of for Minor Dia. of Limit plug Limit plug

Plain GO pIug gauge

Go PIug gauge (Both for working and inspection)

Plain NOT GO plug gauge

NOT GO Working plug gauge
NOT GO inspection plug gauge
NOT GO screw pIug gauge
internal thread internal thread gauges for gauges for
Inspection Working

GO screw pIug gaug

Go Not Go Not Go Go Not Go Go
Pitch diameter tolerance and Minor diameter
tolerance of internal thread
Class 2 Class 2
Tolerance of screw plug gauge and plug gauge

Minimum wear

*Relation of tolerance zone of internal thread and

that of limit gauges for internal thread is shown :
*Pitch diameter of internal thread is virtual pitch
diameter.
*Pitch diameter of screw plug gauge is simple
pitch diameter.

Clearance

Class 2
Class 2

Basic Profile

Basic Pitch Dia. of internal thread 9.026mm

Note : The allowance and tolerance should be

described as 1/2 scale but is simply described
in the size of actual diameter. Basic Minor Dia. of internal thread 8.376mm

. Limit gauges for screw threads

JIS B 0251-2008
Information
Technical

JIS B 0251-1975 Limit gauges for metric coarse threads JIS B 0252-1996 Limit gauge for metric fine threads
Appendix
JIS B 0254-1985 Gauge for parallel pipe threads
JIS B 0253-1985 Gauge for taper pipe threads
JIS B 0256-1975 Limit gauge for unified fine threads,
JIS B 0255-1975 Limit gauge for unified coarse threads Appendix

Technical-10

659
 Length of engagement
Description of products

■Length of engagement
Thread tolerance class is chosen in consideration of "engagement classification" and "engagement length". To realize the stable tapping, it is
necessary to fully understand the relation between these factors and to choose the suitable tolerance class.

On "engagement calssification : middle", the tolerance class 6H is almost always chosen for standard internal threads. However, in case of "engage-
ment length : L", tolerance class 7H can also be chosen.

On M12x1.75, the tolerance of 7H is 25% (50μm) larger than that of 6H. And this widens the selection range of the tolerance class for taps to
customer's advantage.

【M12x1.75】
6H Pitch diameter : 10.863 ~ 11.063mm (tolerance 0.200 mm)
7H Pitch diameter : 10.863 ~ 11.113mm (tolerance 0.250 mm)

1) Engagement classification
classification application

fine precise screw threads with a little allowance

middle standard screw threads used for machines, apparatuses and constructions bodies
screw threads used for construction and building installation, and screw threads for
coarse
which threading operation is very difficult such as threading of hot rolled steel bars.

2) Classification of engagement length

symbol classification limit size engagement length
0.2
S short up to and including 2.24Pd

N normal over 2.24Pd0.2 up to and including 6.7Pd0.2

long over 6.7Pd0.2 めねじ
L internal
thread
d : size designation

3) Selection rule of internal threads and external threads external

 Selection rule of the tolerance class of internal threads おねじ
thread
tolerance position H
engagement length
S N L
engagement classification
fine 4H 5H 6H
middle 5H 6H 7H
coarse - 7H 8H
P : pitch

 Selection rule of the tolerance class of external threads

tolerance position h g
engagement length
S N L S N L
engagement classification
fine (3h4h) 4h (5h4h) - - -
middle (5h6h) 6h (7h6h) (5g6g) 6g (7g6g)
Information

coarse - - - - 8g (9g8g)
Technical

Technical-11

660
 Length of engagement

Description of products
4) engagement length Unit : mm

呼び ピッチ S S N N LL 呼び ピッチ S S NN LL
size pitch size pitch
up to and up to and up to and up to and
M1 S≦0.6 over 0.6＜N≦1.7
0.25 including including over
1.7＜L M10 1.5 S≦5
including over 5＜N≦15
including over
15＜L

M1
M1 0.250.2 0.6 S≦0.5 0.6 0.5＜N≦1.4
1.7 1.4＜L
1.7 M10
M10 1.5 1.25 5 S≦4 5 4＜N≦12
15 12＜L
15

M1.1
M1 0.2 0.25 0.5 S≦0.6 0.5 0.6＜N≦1.7
1.4 1.7＜L
1.4 M10
M10 1
1.25 4 S≦3 4 3＜N≦9
12 9＜L
12

M1.1
M1.1 0.250.2 0.6 S≦0.5 0.6 0.5＜N≦1.4
1.7 1.4＜L
1.7 M10
M10 1 0.75 3 S≦2.4 3 2.4＜N≦7.1
9 7.1＜L
9
M1.2
M1.1 0.2 0.25 0.5 S≦0.6 0.5 0.6＜N≦1.7
1.4 1.7＜L
1.4 M11
M10 1.5
0.75 2.4 S≦5 2.4 5＜N≦15
7.1 15＜L
7.1
M1.2
M1.2 0.250.2 0.6 S≦0.5 0.6 0.5＜N≦1.4
1.7 1.4＜L
1.7 M11
M11 1.5 1 5 S≦3 5 3＜N≦9
15 9＜L
15
M1.4 0.3 S≦0.7 0.7＜N≦2 2＜L M11 0.75 S≦2.4 2.4＜N≦7.1 7.1＜L
M1.2 0.2 0.5 0.5 1.4 1.4 M11 1 3 3 9 9
M1.4 0.2 S≦0.5 0.5＜N≦1.4 1.4＜L M12 1.75 S≦6 6＜N≦18 18＜L
M1.4 0.3 0.7 0.7 2 2 M11 0.75 2.4 2.4 7.1 7.1
M1.6 0.35 S≦0.8 0.8＜N≦2.6 2.6＜L M12 1.5 S≦5.6 5.6＜N≦16 16＜L
M1.4 0.2 0.5 0.5 1.4 1.4 M12 1.75 6 6 18 18
M1.6 0.2 S≦0.5 0.5＜N≦1.5 1.5＜L M12 1.25 S≦4.5 4.5＜N≦13 13＜L
M1.6 0.35 0.8 0.8 2.6 2.6 M12 1.5 5.6 5.6 16 16
M1.8 0.35 S≦0.8 0.8＜N≦2.6 2.6＜L M12 1 S≦3.8 3.8＜N≦11 11＜L
M1.6 0.2 0.5 0.5 1.5 1.5 M12 1.25 4.5 4.5 13 13
M1.8 0.2 S≦0.5 0.5＜N≦1.5 1.5＜L M14 2 S≦8 8＜N≦24 24＜L
M1.8 0.35 0.8 0.8 2.6 2.6 M12 1 3.8 3.8 11 11
M2 0.4 S≦1 1＜N≦3 3＜L M14 1.5 S≦5.6 5.6＜N≦16 16＜L
M1.8 0.2 0.5 0.5 1.5 1.5 M14 2 8 8 24 24
M2 0.25 S≦0.6 0.6＜N≦1.9 1.9＜L M14 1 S≦3.8 3.8＜N≦11 11＜L
M2 0.4 1 1 3 3 M14 1.5 5.6 5.6 16 16
M2.2 0.45 S≦1.3 1.3＜N≦3.8 3.8＜L M15 1.5 S≦5.6 5.6＜N≦16 16＜L
M2 0.25 0.6 0.6 1.9 1.9 M14 1 3.8 3.8 11 11
M2.2 0.25 S≦0.6 0.6＜N≦1.9 1.9＜L M15 1 S≦3.8 3.8＜N≦11 11＜L
M2.2 0.45 1.3 1.3 3.8 3.8 M15 1.5 5.6 5.6 16 16
M2.5 0.45 S≦1.3 1.3＜N≦3.8 3.8＜L M16 2 S≦8 8＜N≦24 24＜L
M2.2
M2.5 0.250.35 0.6 S≦0.8 0.6 0.8＜N≦2.6
1.9 1.9
2.6＜L M15
M16 1 1.5 3.8 S≦5.6 3.8 5.6＜N≦16
11 11
16＜L
M2.5
M3 0.450.5 1.3 S≦1.5 1.3 1.5＜N≦4.5
3.8 3.8
4.5＜L M16
M16 2 1 8 S≦3.8 8 24
3.8＜N≦11 24
11＜L
M2.5
M3 0.350.35 0.8 S≦1 0.8 1＜N≦32.6 2.6
3＜L M16
M17 1.5 1.5 5.6 S≦5.6 5.6 5.6＜N≦16
16 16
16＜L

M3
M3.5 0.5 0.6 1.5 S≦1.7 1.5 1.7＜N≦5
4.5 4.5
5＜L M16
M17 1 1 3.8 S≦3.8 3.8 3.8＜N≦11
11 11
11＜L

M3
M3.5 0.350.35 1 S≦1 1 1＜N≦33 3
3＜L M17
M18 1.5 2.5 5.6 S≦10 5.6 10＜N≦30
16 16
30＜L

M4
M3.5 0.6 0.7 1.7 S≦2 1.7 2＜N≦65 6＜L
5 M18
M17 1 2 3.8 S≦8 3.8 8＜N≦24
11 24＜L
11

M4
M3.5 0.350.5 1 S≦1.5 1 1.5＜N≦4.5
3 4.5＜L
3 M18
M18 2.5 1.5 10 S≦5.610 5.6＜N≦16
30 16＜L
30
M4.5
M4 0.7 0.75 2 S≦2.2 2 2.2＜N≦6.7
6 6.7＜L
6 M18
M18 2 1 8 S≦3.8 8 3.8＜N≦11
24 11＜L
24
M4.5
M4 0.5 0.5 1.5 S≦1.5 1.5 1.5＜N≦4.5
4.5 4.5＜L
4.5 M20
M18 1.5 2.5 5.6 S≦10 5.6 10＜N≦30
16 30＜L
16
M5 0.8 S≦2.5 2.5＜N≦7.5 7.5＜L M20 2 S≦8 8＜N≦24 24＜L
M4.5 0.75 2.2 2.2 6.7 6.7 M18 1 3.8 3.8 11 11
M5 0.5 S≦1.5 1.5＜N≦4.5 4.5＜L M20 1.5 S≦5.6 5.6＜N≦16 16＜L
M4.5 0.5 1.5 1.5 4.5 4.5 M20 2.5 10 10 30 30
M5.5 0.5 S≦1.5 1.5＜N≦4.5 4.5＜L M20 1 S≦3.8 3.8＜N≦11 11＜L
M5 0.8 2.5 2.5 7.5 7.5 M20 2 8 8 24 24
M6 1 S≦3 3＜N≦9 9＜L M22 2.5 S≦10 10＜N≦30 30＜L
M5 0.5 1.5 1.5 4.5 4.5 M20 1.5 5.6 5.6 16 16
M6 0.75 S≦2.4 2.4＜N≦7.1 7.1＜L M22 2 S≦8 8＜N≦24 24＜L
M5.5 0.5 1.5 1.5 4.5 4.5 M20 1 3.8 3.8 11 11
M7 1 S≦3 3＜N≦9 9＜L M22 1.5 S≦5.6 5.6＜N≦16 16＜L
M6 1 3 3 9 9 M22 2.5 10 10 30 30
M7 0.75 S≦2.4 2.4＜N≦7.1 7.1＜L M22 1 S≦3.8 3.8＜N≦11 11＜L
M6 0.75 2.4 2.4 7.1 7.1 M22 2 8 8 24 24
M8 1.25 S≦4 4＜N≦12 12＜L M24 3 S≦12 12＜N≦36 36＜L
M7 1 3 3 9 9 M22 1.5 5.6 5.6 16 16
M8 1 S≦3 3＜N≦9 9＜L M24 2 S≦8.5 8.5＜N≦25 25＜L
M7 0.75 2.4 2.4 7.1 7.1 M22 1 3.8 3.8 11 11
M8 0.75 S≦2.4 2.4＜N≦7.1 7.1＜L M24 1.5 S≦6.3 6.3＜N≦19 19＜L
M8 1.25 4 4 12 12 M24 3 12 12 36 36
M9 1.25 S≦4 4＜N≦12 12＜L M24 1 S≦4 4＜N≦12 12＜L
M8 1 3 3 9 9 M24 2 8.5 8.5 25 25
M9 1 S≦3 3＜N≦9 9＜L
M8
M9 0.750.75 2.4 S≦2.4 2.4 2.4＜N≦7.1
7.1 7.1
7.1＜L M24 1.5 6.3 6.3 19 19

M9 1.25 4 4 12 12 M24 1 4 4 12 12

M9 1 3 3 9 9
Information

M9 0.75 2.4 2.4 7.1 7.1

Technical

Technical-12

661
 Classes of Internal Threads and Classes of Taps
Description of products

1. YAMAWA P Class System

YAMAWA P Class system for thread limits is specified in accordance with JSCTA (The Japan Solid Cutting Tools’ Association). Pitch diameter tolerance
zone for normal size M1∼M52 (U,W up to 2") are shown in the table below. Depending on pitch diameter tolerance and tolerance position, pitch
diameter tolerance zones are classified into three types, A , B and C.
(1) A type : 15μm tolerance. The tolerance of P1, P2, P3… is defined as basic +10∼+25μm, +25∼+40μm, +40∼+55μm and so on, respectively.
(2) B type : 20μm tolerance. The tolerance of P1, P2, P3… is defined as basic +0∼+20μm, +20∼+40μm, +40∼+60μm and so on, respectively.
(3) C type : 40μm tolerance. The tolerance of P2, P3, P4… is defined as basic +0∼+40μm, +20∼+60μm, +40∼+80μm and so on, respectively.
YAMAWA P class system is made in a step form. It can be used to select depending on the tapping conditions.

■ Pitch Tolerance zone for P Class with Nominal size and Pitch
Nominal Size
1mm≦Size≦24mm (7/8) 24mm (7/8)＜Size≦30mm 30mm (11/4)＜Size≦52mm (2)
Pitch

≦0.6mm A type B type B type

0.6mm＜Pitch≦1.75mm B type B type B type

1.75mm＜Pitch≦2mm B type B type C type

2mm＜Pitch≦5mm B type C type C type

μm μm μm

Tolerance=15μm Tolerance=20μm Tolerance=40μm

Basic Pitch Dia. Basic Pitch Dia. Basic Pitch Dia.

2. JIS Limit

Thread limits of taps for metric threads : Today the thread limits of ISO2857 are specified in the main book of JIS, and those of old 1st class, 2nd class
and 3rd class are specified in JIS Appendix. In the thread limits of 1st, 2nd and 3rd classes (old JIS), the pitch diameter tolerances change depending
on nominal size and pitch even if the class is same. On the other hand, in the thread limit of ISO2857 (current JIS), the pitch diameter tolerance is same
and only the tolerance position changes as far as the nominal size is same.
The tolerance, as shown in the next picture (Page 669), is specified as X% of internal thread tolerance and it changes depending on nominal diameter
and pitch. Thread classes of the main book of JIS will be said to be a system located in the middle of YAMAWA P class and old JIS class. To show clearly,
Information
Technical

thread limit classification is called Class 1, Class 2 and Class 3 in current JIS, and 1st class, 2nd class and3rd class in old JIS.

Technical-13

662
 Classes of Internal Threads and Classes of Taps

Description of products
μm
Pitch Dia. tolerance zone of 5H=100μm : (Tolerance 20μm)

class 3

class 2

class 1

Internal thread : Tap : Pitch Dia. tolerance zone

Pitch Dia. tolerance of 5H Basic Pitch Dia.
3. Comparison of pitch diameter tolerance zone for the classes of internal thread and tap.
Following graph shows :
In metric coarce threads
(1) Tap limit classes of YAMAWA P class.
(2) Pitch diameter tolerance zone of 2nd class (Tap) of JIS Appendix (old JIS) and that of class 2 (Tap) ＜class 1 for M1.4 and smaller＞of the main book of JIS (current JIS) .
(3) Pitch diameter tolerance zone of old JIS 2nd class (Internal thread) and that of JIS 6Hclass (Internal thread) ＜5H class for M1.4 and smaller＞
(4) Pitch diameter tolerance zone of standard classes of YAMAWA P class.

P class
Pitch

Basic Pitch Dia. (+)μm

Sizes
JIS class 2
HT,SP,PO
class 1

JIS class 2
HT,SP,PO
class 1

JIS class 2
HT,SP,PO
class 1

JIS class 2
HT,SP,PO
class 1

JIS class 2 P class
SP HT,PO
class 2 Pitch diameter tolerance zone of recommended
class for YAMAWA P class
JIS class 2
SP HT,PO
class 2 Standard class of YAMAWA Spiral Fluted Tap

JIS class 2
HT,SP PO
class 2 Standard class of YAMAWA Spiral Pointed Tap

HT
JIS class 2
SP HT,PO
class 2 class
Pitch diameter tolerance zone of tap in the main book of
JIS class 2 JIS (current JIS).
SP HT,PO
Information

Class 1 for M1.4 and smaller, class 2 for M1.6 and larger
Technical

class 2

SP HT,PO
JIS class 2 Pitch diameter tolerance zone of internal threads in old
JIS class 2.
class 2

JIS class 2 Pitch diameter tolerance zone of internal thread in current

SP HT,PO
JIS (ISO)
class 2 Class 5H for M1.4 and smaller, class 6H for M1.6 and larger

Technical-14

663
 Classes of Internal Threads and Classes of Taps
Description of products

P class
Pitch

Basic Pitch Dia. (+)μm

Sizes
JIS class 2
HT,SP,PO
class 2
JIS class 2
HT,SP,PO
class 2
JIS class 2
SP,PO HT
class 2
JIS class 2
HT,SP,PO
class 2
JIS class 2
HT,SP,PO
class 2

JIS class 2
SP HT,PO
class 2

JIS class 2
SP HT,PO
class 2

JIS class 2
SP HT,PO
class 2
JIS class 2
SP HT,PO
class 2
JIS class 2
SP HT PO
class 2

P class
Pitch

Basic Pitch Dia. (+)μm

Sizes

JIS class 2
SP HT PO
class 2
JIS class 2
SP HT PO
class 2
JIS class 2
SP HT,PO
class 2

JIS class 2
SP HT,PO
class 2
JIS class 2
SP HT,PO
class 2
JIS class 2
SP HT,PO
class 2
Information
Technical

Technical-15

664
 Classes of Internal Threads and Classes of Taps

Description of products
P class
Pitch

Basic Pitch Dia. (+)μm

Sizes

SP JIS class 2
HT,PO
class 2
SP JIS class 2
HT,PO
class 2

4. Standard Class and Oversize

The standard class of the tap which we have been manufacturing for general use is JIS 2nd class. This JIS 2nd class is basically defined as the thread limit
of the tap which can cut the internal thread of old JIS 2nd class. With technical innovation such as various tap classification, high precision tapping
machines, workpiece materials and diversity of workpieces' dimension, conventional products having JIS 2nd class could not always satisfy customers
requirement due to following situations.
(1) In cutting taps, the shape of flutes influences the thrust of axial direction. We explain about oversize cutting tendency caused by the thrust force
of axial direction by referring to that of Straight fluted hand taps as a basic. Spiral pointed taps have little tendency of oversize cutting, but Spiral
fluted taps have a tendency of oversize cutting.
(2) Due to the relation between pitch diameter of JIS 2nd class tap and that of GO thread plug gauge for the internal thread of old JIS 2nd class, if the
cutting edge of tap wears normally, the taps will become gauge out quickly resulting in short tool life.
(3) Due to the material or shape of workpiece, the material can shrink. In these cases, it would be better to use oversized taps to compensate for
shinkage after tapping.
(4) When plating is to be applied to internal threads after threading, we should use oversized taps to compensate for the thickness amount of plating.
(5) Where little tendency of oversize cutting is expected, but large wear in tools is expected during tapping operation, it is better to consider using
oversized taps as much as possible.
From these situations, in spiral pointed taps, spiral fluted taps and various types of special purpose taps, YAMAWA has adopted the P class limit
system which is explained in previous pages. Depending on the type and designation of taps, YAMAWA has selected from the P class system the
tap's thread limit which the tap manufacturer recommends for general tapping operation. From the reason of (1) stated above, even in the same tap
designation, the recommendation for spiral pointed taps is different from that for spiral fluted taps. Especially in the standard products of spiral
pointed taps and spiral fluted taps, YAMAWA has specified the recommendation differently in the relation to oversize cutting tendency. Oversize
taps mean the taps of which thread limits are oversize above the recommendation. This is due to the reasons (3), (4) and (5) stated above. Usually for
oversize taps, YAMAWA recommends the taps which thread tolerance classes are one or two steps above the standard recommendation.
As you can see in the picture drawn in previous pages, the recommendation can be used for cutting JIS (ISO) 6H internal threads.
5. Classes of Taps for European market, and PD tolerance zone of taps. Unit : μm
2B 2B — G —
+28 +12 +26 +11 1/ 16 1/8 +43 +21
+30 +13 +28 3/ 32 1/4 +50 +25
+32 +14 +29 +12 1/ 3/ +50 +25
8 8
+34 +31 +13 5/ 1/ +57 +28
32 2
+35 +14 3/ 5/ +57 +28
16 8
+38 +18 +34 +15 1/ 3/ +57 +28
4 4
+39 +18 +36 +16 5/ +72 +36
16
+42 +20 +38 +17 3/ 1/4 +72 +36
8

+43 +20 +18 7/ 1/ +72 +36

16 2
1/4 +46 +22 +19 1/
2
5/ +49 +23 1/4 +43 +19 9/
16 16
3/ +53 +25 5/ 16 +46 +20 5/
8 8
7/ +56 +27 3/ +48 +20 3/
16 8 4
1/ +58 +28 7/ +51 +22 7/
2 16 8
9/ +60 +29 1/ +52 +23
16 2
5/
8 +63 +30 9/
16 +54 +23 1/8
3/ +66 +31 5/ +56 +23 1/4
Information

4 8
Technical

7/ +70 +33 3/ +60 +25 3/

8 4 8
+73 +35 7/ +64 +27 1/
8 2

+67 +29 5/
8
3/
4
7/ +48
8

Technical-16

665
 Classes of Internal Threads and Classes of Taps

6. Comparison table of tap's classes for American market and PD tolerance for ANSI unified internal threads.
Description of products

Class P1 P3 P5
Designation P2 P4 P6
PD tolerance of
210 220 230 240 internal threads

Basic Pitch Dia. (+)μm for 3B for 2B

μm μm
P1
№2-56 UNC Pclass 53 70
GH2
Pclass oversize
P1
№3-48 UNC
ANSI
55 75
GH2 ANSI oversize

P1 P2 P3 internal threads 3B
№4-40 UNC internal threads 2B 60 83
GH2 GH3 GH4 GH5
P1
№5-40 UNC 63 83
GH2

Class P2 P4 P6
Designation P3 P5 P7
PD tolerance of
210 220 230 240 internal threads

Basic Pitch Dia. (+)μm for 3B for 2B

μm μm
P2 P3 P4
№6-32 UNC 68 93
GH2 GH3 GH4 GH5 GH6 GH7
P2 P3 P4
№8-32 UNC 71 96
GH2 GH3 GH4 GH5 GH6 GH7
P2 P3 P4
№10-24 UNC 80 108
GH3 GH5 GH6 GH7
P2
№12-24 UNC 82 110
GH3
P2 P3 P4
1/4-20 UNC 90 123
GH3 GH5 GH6 GH7
P2 P3 P4
5/16-18 UNC 98 134
GH3 GH5 GH7
P2 P3 P4
3/8-16 UNC 108 144
GH3 GH5 GH7
P2 P3
7/16-14 UNC 116 154
GH3 GH5
P2 P3 P4
1/2-13 UNC 121 165
GH3 GH5 GH7
P2
9/16-12 UNC 128 172
GH3
P3 P4
5/8-11 UNC 136 182
GH3 GH5
P3 P4
3/4-10 UNC 144 195
GH3 GH5
P3
7/8-9 UNC 154 207
GH4

Class P2 P4 P6 P8
Information
Technical

Designation P3 P5 P7
PD tolerance of
210 220 230 240 internal threads

Basic Pitch Dia. (+)μm for 3B for 2B

μm μm
P4
1-8 UNC 167 223
GH4

Technical-17

666
10. Guide to Thread Forming Taps (Roll Taps)

Thread Forming Taps are the tools used for producing internal threads by a thread forming process. Currently, YAMAWA's Thread Forming Taps have

Description of products
a good reputation by being used in large area. They are widely used along with the diversity of workpieces and with the change into miniaturization
of workpieces. Followings are the characteristics and features of Thread Forming Taps (Roll Tap) which cutting type taps do not have.

<Features of Roll Taps>

○Tapping without producing chips. They are suitable for blind hole tapping. In producing internal threads with no chips, they save you a
time for chip disposal.
○Roll taps are stronger than cutting taps due to their design. The effect of fluteless design gives a large cross-section area to the tap,
which effectively eliminates the problem of chip jamming and thus make Roll taps very strong.
○Roll taps produce excellent pitch diameter well within pitch diameter tolerances. Material deformation process produces the
internal threads with good surface finish as well as precise pitch diameter.
○High efficiency and tool life The configuration of the lobes at the crests of the tap threads make high speed tapping possible and extends
tool life compared with cutting type taps. The addition of a supplemental tap surface treatment, such as Oxide, Nitride, TiN, and TiCN can extend
tool life 2 to 20 times over an uncoated (bright) taps performance.
<Points to note during a Roll tapping operation>
○Tapping torque is 2 to 3 times larger than that of cutting type taps.
○Roll tapping is only applicable to stringy materials.
○The deviation of hole size before tapping should be about 5% of pitch. The control of hole size before tapping should be more severe than that of
cutting type taps.
○The selection of lubricants is important to prevent sticking or welding.
○Burrs at the face of an internal thread are larger than those produced by cutting type taps, in some cases it is necessary to take additional counter-
sink processing at the top of hole.
○In the minor diameter of internal thread, U-shape form (Tine form) at the hole entrance can be seen. U-shape form is never seen when using cutting
type taps.
<Selection of YAMAWA Roll Taps>
○Types of Roll Taps YAMAWA produces various types of Roll Taps which include General purpose taps, Special purpose taps for non-ferrous and
steel, as well as special purpose taps with surface treatment for the specified applications. To provide for longer tool life, specially developed
premium materials are also used together with physical vapor deposition (PVD) such as TiN and TiCN. In particular, OL-RZ is superior product
developed for dry machining with good regards to tapping environment and performance.
○Tap Materials YAMAWA's standard tap material is SKH58 designed for improving torque, superior anti-friction properties as well as toughness.
To extend tool life, we use SKH56, or SKH10(Powder HSS) which is the best tap material for antifriction.
○Tolerance Class Using the datum 12.7μm in a step form, in accordance with ANSI standard GH class, we made up YAMAWA's G class system.
The differences in materials being Roll tapped, as well as hole size, contribute to differences in thread forming. YAMAWA offers 2 to 3 oversized tap
tolerance classes in order to achieve the most suitable internal thread pitch diameter size.
○Chamfer length Chamfer lengths : 2 pitches for blind hole use and 4 pitches for through hole use. Basically 4 pitches have longer tool life than
2 pitches because force applied on one blade at 4 pitch chamfer is smaller than that at 2 pitch chamfer. However, it is difficult to say about tool life
in a few words because each different tapping condition influences the tool life.
<Shape of internal threads and the ratio of thread engagement affected by bored hole diameter>
Compared with the basic height of thread engagement, the actual height of the thread engagement is called "thread engagement ratio" in percentage.
Depending on the bored hole diameter, internal threads and thread engagement ratio will change.
In tapping, the tapping condition must be chosen by refering to the thread engagemet ratio.
In tapping, it can reduce cutting space and forming space to make bored hole diameters as large as possible. This, through reducing the load on taps,
can restrict tap's wear and damage.

S50C, minor diameter of threads cut Aluminum, minor diameter of threads formed
M24x3 M25x2
minor dia tolerance of internal threads minor dia tolerance of internal threads
φ20.752~φ21.252 φ22.835~φ23.210

【Aluminum, internal threads formed ①】

【S50C internal threads cut ①】 Internal External Internal External
M25x2
M24x3 threads threads threads threads
bored hole size :φ23.903
bored hole size :φ20.652
minor diameter of finished internal threads : 22.723mm
minor dia tolerance of internal threads NG
minor dia tolerance of internal threads NG
thread engagement ratio : 103.1%
thread engagement ratio : 105.2%
【Aluminum, internal threads formed ③】
【S50C internal threads cut ③】
M25x2
M24x3
bored hole size :φ24.042mm
bored hole size :φ21.000
minor diameter of finished internal threads : 23.067mm
minor dia tolerance of internal threads: Middle
Information

minor dia tolerance of internal threads : Middle

Technical

thread engagement ratio : 92.4%

thread engagement ratio : 89.3%
【Aluminum, internal threads formed ⑤】
【S50C internal threads cut ⑤】
M25x2
M24x3
bored hole size :φ24.240mm
bored hole size :φ21.352
minor diameter of finished internal threads : 23.462mm
minor dia tolerance of internal threads NG
minor dia tolerance of internal threads NG
thread engagement ratio : 81.5%
thread engagement ratio : 71.0%

Technical-18

667
 10. Guide to Threads Forming Taps (Roll Taps)

<Condition of use>
Description of products

○Relation between tapping speed and tapping lubricant depending on work materials.

Tapping Speed
Work Material Tapping lubricant*

Die Cast Materials Sulfer-chlorinated Mineral oil

Aluminum and Aluminum Alloy Chlorinated non-soluble oil
Cold Drawn, Cold Forged, Cast Non-soluble oil
Die Cast Materials
Zinc and Zinc Alloy
Cold Drawn, Cold Forged, Cast
Copper Cold Forged, Cast
Brass Cold Drawn, Cold Forged
Mild Steel, Medium Carbon Steel, Stainless Steel Chlorinated non-soluble oil
Steel
Free Cutting Steel, Soft Magnetic Iron
*Basis of selection of JIS symbols
Note : It is necessary to carefully select a suitable tapping speed taking into consideration : machining conditions, style of tap, number of tap chamfered threads, work piece design, material being tapped,
hole condition and type of tapping fluid.

<Accuracy of roll taps>

■YAMAWA G class system Thread Forming Taps
○YAMAWA G class system is made by using the datum 0.0005 inch (12.7μm) in a step form in accordance with ANSI standard GH class.
○The upper deviation of G class is decided by rounding off the grade No.× 12.7 to 1 decimal.
○The lower deviation of G class is specified in the same upper tolerance of one lower step.
○The tolerances are either 12 μm or 13μm.

■Comparison of pitch tolerance zone between class 2 internal threads and recommended Roll Taps G Class.
M1.4×0.3

M1.6×0.35

M1.7×0.35 YAMAWA Class 2

M1.8×0.35 YAMAWA G Class Taps
M2×0.4

M2.5×0.45

M2.6×0.45

M3×0.5

M3.5×0.6

M4×0.7

M5×0.8

M6×1

M8×1.25

M10×1.5

M12×1.75

Basic Pitch Dia. (+)μm

Tolerance area

■Roll taps for miniature threads, Accuracy GS class

○GS class is the accuracy class special for roll taps for miniature threads.
■Comparison table of PD tolerance of GS class of roll taps for miniature threads and 4H5 internal threads.
8 18
GS1 23
GS2 28
13 GS3 33
18 GS4
23
10 20 30 40 45
Information
Technical

S0.6×0.15 GS2
4H5 internal threads
S0.7×0.175 GS3

S0.8×0.2 GS class tap

GS3

S0.9×0.225 GS4

Basic size of pitch diameter Tolerance area (+)μm

Technical-19

668
 How to set the tap's oversize to meet with the coating
margin of internal threads

Description of products
1) Relation between coating thickness and pitch diameter when applied with coating
Dwg.1 shows the relation between coated internal thread and pitch diameter
* Thickness of coating is measured at right angle to flank face. Pitch diamete is measured at right angle to axis (radially).

Drawing 1

Coating thickness 3μm

half of pitch diameter

decrease (6μm)

Where t (coating thickness) equals 3μm, by using following formula, oversize is roughly caluculated.
Pitch diameter decrease 2t×2 (both side of threads) = 3μm×2×2 =12 μm (rough over size)
2) How to specify taps for coating
1. We suppose the accuracy of finished internal threads is 6H class, and inspection is done with GP-6H and NP-6H.
2. We suppose the disperse of coating thickness is controlled within the tolerance of 8~16μm.
The disperse of coating thickness, when it is exchanged into pitch diameter, will become the disperse of 32~64μm.
3. Accuracy of internal threads before coating is the thread accuray which GP-6H goes through (OK), even when max coating (64μm) is applied.
And this accuracy is the thread accuray which NP-6H does not go through (OK), when min coating (32μm) is applied.
4. We propose followings for inspecting the accuracy of internal threads before coating :
GO gauge before coating : GP-6H+64
5. Next, based on GO gauge before coating and NOT GO gauge before coating, we study to specify the suitable accuracy of the tap before coating.

M6×1 How to specify the accuracy of tap before coating (Coating thickness 8~16μm)
Minor diameter of JIS 6H Minor diameter of JIS 6H

GP-6H

NP-6H

Internal threads before coating Internal threads before coating

GP-6H+64

NP-6H+32

Suggested cutting taps

Suggested roll taps

(μm)
Basic size of pitch diameter : 5.350mm

M6×1 Basic size of pitch diameter : 5.350mm

Internal thread tolerance 6H : 0~+150μm (Tolerance : 150μm)
Information
Technical

Accuracy GP-6H : +7~+17μm Accuracy NP-6H : +150~+160μm

Internal thread tolerance before coating : +64~+182μm (Tolerance : 118μm)
Accuracy GP-6H+64 : +71~+81μm Accuracy NP-6H+32 : +182~+192μm
Accuracy of suggested cutting taps (P5.5) : +90~+110μm
Accuracy of suggested roll taps (G12) : +140~+152μm

Technical-20

669
 12. Recommended bored hole sizes

■For Metric Threads

Production data

Unit : mm
Minor diameter of internal threads (D1) Minor diameter of internal threads (D1)
Nominal size Drill Size Nominal size Drill Size

M5.5×0.5 5.099 4.959 5.0

The recommended tap drill sizes indicated above are for JIS 6H (Class 2) Metric Threads.
• D1: Minor diameter of JIS 6H (Class 2) internal thread. The Minor diameters D1 shown in ( ) are of 5H (Class 2) for coarse threads and of 4H • 5H (Class 1) for fine threads.
• ※Marked sizes have been eliminated from JIS.
Information
Technical

Technical-21

670
 12. Recommended bored hole sizes

Production data
Unit : mm
Minor diameter of internal threads (D1) Minor diameter of internal threads (D1)
Nominal size Drill Size Nominal size Drill Size

• D1: Minor diameter of JIS 6H (Class 2) internal thread.

Information
Technical

Technical-22

671
 12. Recommended bored hole sizes

■For Unified Threads

Production data

Unit : mm
Minor diameter of internal threads (D1) Minor diameter of internal threads (D1)
Nominal size Drill Size Nominal size Drill Size

• The recommended tap drill sizes indicated above are for JIS Class 2B UNC & UNF threads, and ANSI B1.1 Class 2B UNEF, UN & UNS threads.
Information
Technical

Technical-23

672
 12. Recommended bored hole sizes

■For Metric Threads Using with Helical Coil Wire Inserts

Production data
Unit : mm
Bored hole size Bored hole size
Nominal size Drill Size Nominal size Drill Size

• The figures listed above are according to the data provided by helical coil wire insert manufacturers.

■Pipe Thread (Rc, PT) Unit : mm

Drill Size
Nominal size Internal Thread Minor Dia. Internal Thread Minor Dia.
On [Min.] Length of Useful Thread On [Min.] Gauge Length
With Reaming Before Tapping Without Reaming Before Tapping

■For Whitworth Coarse Threads ■For Sewing Machine Threads

Unit : mm Unit : mm
Minor diameter of internal threads (D1) Minor diameter of internal threads (D1)
Nominal size Drill Size Nominal size Drill Size

※
※
Information
Technical

• D1: Minor diameter of JIS Class 2 internal thread.

• Whitworth Threads have been eliminated from JIS.
• ※Marked sizes are in accordance with BSW.

Technical-24

673
 12. Recommended bored hole sizes

■Pipe Thread
Production data

○Rp, PS Unit : mm ○G, PF Unit : mm

Minor Diameter of JIS internal thread (D1) Minor Diameter of JIS internal thread (D1)
Nominal size Drill Size Nominal size Drill Size
Max. Min. Max. Min.

■American Standard Pipe Thread Unit : mm

Tap Drill Size
NPT NPSC
Nominal size
With Reaming Before Tapping Without Reaming Before Tapping
mm inch mm inch mm inch

・The drill sizes are according to ANSI/ASME B1.20.1-1983 PIPE THREADS, GENERAL PURPOSE (INCH) (partial listing).
Information
Technical

Technical-25

674
 12. Recommended bored hole sizes

■Dryseal American Standard Pipe Thread

Production data
Unit : mm
Tap Drill Size
NPT NPSC
Nominal size
With Reaming Before Tapping Without Reaming Before Tapping
mm inch mm mm inch

・The drill sizes are according to ANSI B1.20.3-1976 Dryseal Pipe Threads (Inch) (partial listing).

■Percentage of Thread Engagement & Relation between Percentage of Thread Height and Area Removed at A Thread Height

Percentage of Thread Engagement

percentage of Area Removed (%)

percentage of Thread Height (%)

internal
threads
Basic Major Dia. − Hole Size Before Tapping
100
2× (Basic Thread Overlap)

Basic Thread Overlap

Metric & Unified Thread 0.5413P
Whitworth Thread 0.5664P
Pipe Thread (Rc, Rp, G, PT, PS, PF) 0.6403P
P=Pitch

As shown above, when the thread height increases, the amount of material to be removed increases rapidly, so it is an advantage to tap users to keep the
hole size (thread minor diameter) as large as possible.
Information
Technical

Technical-26

675
 13. Recommended Hole Sizes for Thread Forming Taps
Production data

■For Metric Threads Unit : mm

Recommended Recommended Recommended
Tolerance Tolerance Tolerance
Nominal size Hole Size Nominal size Hole Size Nominal size Hole Size
Class of Tap Class of Tap Class of Tap
Max. Min. Max. Min. Max. Min.

・According to the ductility, hardness and dimension of the workpiece to be tapped, the recommended hole sizes for thread forming tapping may have to be altered.
The values listed above should only be used as an aid in selecting suitable drills when using thread forming taps, the correct hole sizes should be decided based on test result.
Further, the values listed above are suitable for 0.5D~2D threading length in relatively ductile materials (D : thread major diameter).

■For Unified Threads Unit : mm

Recommended Recommended Recommended
Tolerance Tolerance Tolerance
Nominal size Hole Size Nominal size Hole Size Nominal size Hole Size
Class of Tap Class of Tap Class of Tap
Max. Min. Max. Min. Max. Min.

・According to the ductility, hardness and dimension of the workpiece to be tapped, the recommended hole sizes for thread forming tapping may have to be altered.
The values listed above should only be used as an aid in selecting suitable drills when using thread forming taps, the correct hole sizes should be decided based on test result.
Further, the values listed above are suitable for 0.5D~2D threading length in relatively ductile materials (D : thread major diameter).
Information
Technical

Technical-27

676
14. Bar diameter for external threads (for cutting type dies)

Production data
■Tolerable limit size and tolerance of outside diameter for metric external screws Unit : mm
outside diameter of external screws outside diameter of external screws
size pitch size pitch
designation ISO old JIS designation ISO old JIS
P ｄmax ｄmin Td ｄmax ｄmin Td P ｄmax ｄmin Td ｄmax ｄmin Td
0.25 1.000 0.933 0.067 0.985 0.940 0.045 2 15.962 15.682 0.280 15.950 15.740 0.210
M1
0.2 1.000 0.944 0.056 0.980 0.930 0.050 M16 1.5 15.968 15.732 0.236 15.960 15.790 0.170
0.25 1.100 1.033 0.067 1.100 1.033 0.067 1 15.974 15.794 0.180 15.960 15.810 0.150
M1.1
0.2 1.100 1.044 0.056 1.100 1.044 0.056 1.5 16.968 16.732 0.236 16.968 16.732 0.236
M17
0.25 1.200 1.133 0.067 1.185 1.140 0.045 1 16.974 16.794 0.180 16.974 16.794 0.180
M1.2
0.2 1.200 1.144 0.056 1.180 1.130 0.050 2.5 17.958 17.623 0.335 17.950 17.710 0.240
0.3 1.400 1.325 0.075 1.380 1.320 0.060 2 17.962 17.682 0.280 17.950 17.650 0.300
M1.4 M18
0.2 1.400 1.344 0.056 1.380 1.330 0.050 1.5 17.968 17.732 0.236 17.950 17.780 0.170
0.35 1.581 1.496 0.085 1.581 1.496 0.085 1 17.974 17.794 0.180 17.960 17.810 0.150
M1.6
0.2 1.583 1.527 0.056 1.583 1.527 0.056 2.5 19.958 19.623 0.335 19.950 19.710 0.240
0.35 1.781 1.696 0.085 1.781 1.696 0.085 2 19.962 19.682 0.280 19.950 19.650 0.300
M1.8 M20
0.2 1.783 1.727 0.056 1.783 1.727 0.056 1.5 19.968 19.732 0.236 19.950 19.780 0.170
0.4 1.981 1.886 0.095 1.980 1.890 0.090 1 19.974 19.794 0.180 19.960 19.810 0.150
M2
0.25 1.982 1.915 0.067 1.980 1.930 0.050 2.5 21.958 21.623 0.335 21.950 21.710 0.240
0.45 2.180 2.080 0.100 2.180 2.080 0.100 2 21.962 21.682 0.280 21.950 21.650 0.300
M2.2 M22
0.25 2.182 2.115 0.067 2.182 2.115 0.067 1.5 21.968 21.732 0.236 21.950 21.780 0.170
0.45 2.480 2.380 0.100 2.480 2.380 0.100 1 21.974 21.794 0.180 21.960 21.810 0.150
M2.5
0.35 2.481 2.396 0.085 2.481 2.396 0.085 3 23.952 23.577 0.375 23.940 23.680 0.260
0.5 2.980 2.874 0.106 2.980 2.874 0.106 2 23.962 23.682 0.280 23.940 23.640 0.300
M3 M24
0.35 2.981 2.896 0.085 2.980 2.880 0.100 1.5 23.968 23.732 0.236 23.950 23.780 0.170
0.6 3.479 3.354 0.125 3.470 3.360 0.110 1 23.974 23.794 0.180 23.960 23.810 0.150
M3.5
0.35 3.481 3.396 0.085 3.480 3.380 0.100 2 24.962 24.682 0.280 24.940 24.640 0.300
0.7 3.978 3.838 0.140 3.978 3.838 0.140 M25 1.5 24.968 24.732 0.236 24.950 24.780 0.170
M4
0.5 3.980 3.874 0.106 3.970 3.860 0.110 1 24.974 24.794 0.180 24.960 24.810 0.150
0.75 4.478 4.338 0.140 4.470 4.340 0.130 M26 1.5 25.968 25.732 0.236 25.950 25.780 0.170
M4.5
0.5 4.480 4.374 0.106 4.470 4.360 0.110 3 26.952 26.577 0.375 26.940 26.680 0.260
0.8 4.976 4.826 0.150 4.976 4.826 0.150 2 26.962 26.682 0.280 26.962 26.682 0.280
M5 M27
0.5 4.980 4.874 0.106 4.970 4.860 0.110 1.5 26.968 26.732 0.236 26.950 26.780 0.170
M5.5 0.5 5.480 5.374 0.106 5.470 5.360 0.110 1 26.974 26.794 0.180 26.974 26.794 0.180
1 5.974 5.794 0.180 5.970 5.820 0.150 2 27.962 27.682 0.280 27.940 27.640 0.300
M6
0.75 5.978 5.838 0.140 5.970 5.850 0.120 M28 1.5 27.968 27.732 0.236 27.950 27.780 0.170
1 6.974 6.794 0.180 6.970 6.820 0.150 1 27.974 27.794 0.180 27.960 27.810 0.150
M7
0.75 6.978 6.838 0.140 6.970 6.850 0.120 3.5 29.947 29.522 0.425 29.940 29.660 0.280
1.25 7.972 7.760 0.212 7.960 7.790 0.170 3 29.952 29.577 0.375 29.952 29.577 0.375
M8 1 7.974 7.794 0.180 7.970 7.830 0.140 M30 2 29.962 29.682 0.280 29.940 29.640 0.300
0.75 7.978 7.838 0.140 7.970 7.830 0.140 1.5 29.968 29.732 0.236 29.950 29.780 0.170
1.25 8.972 8.760 0.212 8.960 8.790 0.170 1 29.974 29.794 0.180 29.960 29.810 0.150
M9 1 8.974 8.794 0.180 8.970 8.830 0.140 2 31.962 31.682 0.280 31.940 31.640 0.300
M32
0.75 8.978 8.838 0.140 8.970 8.830 0.140 1.5 31.968 31.732 0.236 31.950 31.780 0.170
1.5 9.968 9.732 0.236 9.960 9.770 0.190 3.5 32.947 32.522 0.425 32.940 32.660 0.280
1.25 9.972 9.760 0.212 9.960 9.810 0.150 3 32.952 32.577 0.375 32.952 32.577 0.375
M10 M33
1 9.974 9.794 0.180 9.970 9.820 0.150 2 32.962 32.682 0.280 32.962 32.682 0.280
0.75 9.978 9.838 0.140 9.978 9.838 0.140 1.5 32.968 32.732 0.236 32.950 32.780 0.170
1.5 10.968 10.732 0.236 10.968 10.732 0.236 M35 1.5 34.968 34.732 0.236 34.950 34.780 0.170
M11 1 10.974 10.794 0.180 10.970 10.820 0.150 4 35.940 35.465 0.475 35.930 35.630 0.300
0.75 10.978 10.838 0.140 10.978 10.838 0.140 3 35.952 35.577 0.375 35.952 35.577 0.375
11.950 11.760 0.190 M36 35.940 35.640 0.300
1.75 11.966 11.701 0.265 2 35.962 35.682 0.280
1.5 11.968 11.732 0.236 11.960 11.790 0.170 1.5 35.968 35.732 0.236 35.950 35.780 0.170
M12 11.972 11.760 0.212 37.950 37.780 0.170
1.25 11.972 11.760 0.212 M38 1.5 37.968 37.732 0.236
1 11.974 11.794 0.180 11.960 11.810 0.150 4 38.940 38.465 0.475 38.930 38.630 0.300
2 13.962 13.682 0.280 13.950 13.740 0.210 3 38.952 38.577 0.375 38.952 38.577 0.375
M39
M14 1.5 13.968 13.732 0.236 13.960 13.790 0.170 2 38.962 38.682 0.280 38.962 38.682 0.280
1 13.974 13.794 0.180 13.960 13.810 0.150 1.5 38.968 38.732 0.236 38.968 38.732 0.236
1.5 14.968 14.732 0.236 14.960 14.790 0.170 3 39.952 39.577 0.375 39.952 39.577 0.375
M15 14.810 0.150 39.640 0.300
1 14.974 14.794 0.180 14.960 M40 2 39.962 39.682 0.280 39.940
1.5 39.968 39.732 0.236 39.950 39.780 0.170
ISO tolerance area Class 6g (M1.6 and larger) 6h (M1.4 and smaller) old JIS 2nd class
Information

old JIS 2nd class

Technical

・ISO : from table 2 JIS B0209-2 and from table 1 JIS B0209-3
・Old JIS : from the tolerable limit size and the tolerance of metric coarse threads (for 2nd
class external threads, JIS B 0209-1982 appendix 1, appendix 1 attachment 4. from the
tolerable limit size and the tolerance of metric fine threads (for 2nd class external
threads), JIS B 0211-1982 appendix, appendix attachiment 4

Technical-28

677
 14. Bar diameter for external threads (for cutting type dies)

■Tolerable limit size and tolerance of outside diameter

Production data

Unit : mm  for unified external screws (for 2A thread) Unit : mm

outside diameter of external screws outside diameter of external screws
size pitch size designation
designation ISO old JIS ｄmax ｄmin Td
P ｄmax ｄmin Td ｄmax ｄmin Td No0-80UNF 1.511 1.431 0.080
4.5 41.937 41.437 0.500 41.930 41.610 0.320 No.1-64UNC 1.838 1.743 0.095
4 41.940 41.465 0.475 41.940 41.465 0.475 No.1-72UNF 1.838 1.751 0.087
M42 3 41.952 41.577 0.375 41.952 41.577 0.375 No.2-56UNC 2.169 2.066 0.103
2 41.962 41.682 0.280 41.940 41.640 0.300 No.2-64UNF 2.169 2.073 0.096
1.5 41.968 41.732 0.236 41.950 41.780 0.170 No.3-48UNC 2.496 2.383 0.113
4.5 44.937 44.437 0.500 44.930 44.610 0.320 No.3-56UNF 2.496 2.393 0.103
4 44.940 44.465 0.475 44.940 44.465 0.475 No.4-40UNC 2.824 2.695 0.129
M45 3 44.952 44.577 0.375 44.952 44.577 0.375 No.4-48UNF 2.827 2.713 0.114
2 44.962 44.682 0.280 44.940 44.640 0.300 No.5-40UNC 3.154 3.026 0.128
1.5 44.968 44.732 0.236 44.950 44.780 0.170 No.5-44UNF 3.157 3.036 0.121
5 47.929 47.399 0.530 47.930 47.590 0.340 No.6-32UNC 3.484 3.333 0.151
4 47.940 47.465 0.475 47.940 47.465 0.475 No.6-40UNF 3.484 3.356 0.128
M48 3 47.952 47.577 0.375 47.952 47.577 0.375 No.8-32UNC 4.142 3.991 0.151
2 47.962 47.682 0.280 47.940 47.640 0.300 No.8-36UNF 4.145 4.006 0.139
1.5 47.968 47.732 0.236 47.950 47.780 0.170 No.10-24UNC 4.800 4.618 0.182
No.10-32UNF 4.803 4.651 0.152
No.12-24UNC 5.461 5.279 0.182
No.12-28UNF 5.461 5.296 0.165
1/4-20UNC 6.322 6.117 0.205
1/4-28UNF 6.324 6.160 0.164
5/16-18UNC 7.907 7.687 0.220
5/16-24UNF 7.909 7.727 0.182
3/8-16UNC 9.491 9.254 0.237
3/8-24UNF 9.497 9.315 0.182
7/16-14UNC 11.076 10.816 0.260
7/16-20UNF 11.079 10.874 0.205
1/2-13UNC 12.661 12.386 0.275
1/2-20UNF 12.666 12.462 0.204
9/16-12UNC 14.246 13.958 0.288
9/16-18UNF 14.251 14.031 0.220
5/8-11UNC 15.834 15.528 0.306
5/8-18UNF 15.839 15.619 0.220
3/4-10UNC 19.004 18.677 0.327
3/4-16UNF 19.011 18.774 0.237
7/8-9UNC 22.176 21.824 0.352
7/8-14UNF 22.184 21.923 0.261
1-8UNC 25.349 24.969 0.380
1-12UNF 25.354 25.065 0.289
11/8-7UNC 28.519 28.103 0.416
11/8-12UNF 28.529 28.240 0.289
11/4-7UNC 31.694 31.278 0.416
11/4-12UNF 31.704 31.415 0.289
13/8-6UNC 34.864 34.402 0.462
1 3/8-12UNF 34.876 34.588 0.288
1 1/2-6UNC 38.039 37.577 0.462
1 1/2-12UNF 38.051 37.763 0.288
1 3/4-5UNC 44.381 43.861 0.520
2-4 1/2UNC 50.726 50.168 0.558
・from table 4 JIS B0210 and table 4 JIS B0212
Information
Technical

Technical-29

678
 14. Bar diameter for external threads (for cutting type dies)

■Tolerable limit size and tolerance of outside diameter for sewing

Production data
 machine screw external screws (for 2nd thread) Unit : mm
outside diameter of external screws
thread designation
ｄmax ｄmin Td
1/16 SM80 1.588 1.518 0.070
5/64 SM64 1.984 1.904 0.080
3/32 SM56 2.381 2.286 0.095
3/32 SM100 2.381 2.306 0.075
1/8 SM40 3.175 3.045 0.130
1/8 SM44 3.175 3.055 0.120
1/8 SM48 3.175 3.065 0.110
9/64 SM40 3.572 3.442 0.130
11/64 SM40 4.366 4.236 0.130
3/16 SM24 4.762 4.602 0.160
3/16 SM28 4.762 4.602 0.160
3/16 SM32 4.762 4.602 0.160
7/32 SM32 5.556 5.396 0.160
15/64 SM28 5.953 5.773 0.180
1/4 SM24 6.350 6.170 0.180
1/4 SM40 6.350 6.220 0.130

・from table 2 JIS B 0226 (void in 2001)

■Pipe taper threads (R, PT) Unit : mm

■Pipe pararell threads (G, PF) Unit : mm
bar diameter (ref.) outside diameter of external screws
Designation Designation
Straight taper (dia of thread end) ｄmax ｄmin
R 1/16 7.9 7.5 G 1/16 7.723 7.509
R 1/8 9.9 9.5 G 1/8 9.728 9.514
R 1/4 13.4 12.8 G 1/4 13.157 12.907
R 3 /8 16.9 16.3 G 3 /8 16.662 16.412
R 1/2 21.3 20.5 G 1/2 20.955 20.671
R 3/4 26.8 25.9 G 5/8 22.911 22.627
R 1 33.7 32.7 G 3/4 26.441 26.157
R 1・1/4 42.3 41.2 G 7/8 30.201 29.917
R 1・1/2 48.2 47.1 G 1 33.249 32.889
R 2 60.1 58.7 G 1・1/4 41.910 41.550
G 1・1/2 47.803 47.443
G 2 59.614 59.254 Information
Technical

Technical-30

679
 15. Bar diameter of external screws (for thread rolling dies)
Production data

○NRS-D recommendation for bar diameter

for metric external screws Unit : mm
recommended bar diameter
designation
Max Min
M3×0.5 2.64 2.62
M4×0.7 3.54 3.52
M5×0.8 4.40 4.38
M6×1 5.30 5.28
M8×1.25 7.10 7.07

○RS-D recommendation for bar diameter for metric external screws Unit : mm
recommended bar diameter recommended bar diameter
designation designation
Max Min Max Min
M1×0.25 0.808 0.785 M2.3×0.4 1.998 1.968
M1.1×0.25 0.918 0.891 M2.3×0.25 2.096 2.071
M1.2×0.25 1.007 0.984 M2.5×0.45 2.162 2.126
M1.4×0.3 1.168 1.142 M2.5×0.35 2.228 2.196
M1.6×0.35 1.332 1.300 M2.6×0.45 2.262 2.226
M1.7×0.35 1.432 1.401 M2.6×0.35 2.318 2.278
M1.8×0.35 1.530 1.498 M3×0.5 2.627 2.589
M2×0.4 1.699 1.669 M3×0.35 2.718 2.677
M2×0.25 1.796 1.771 M4×0.5 3.607 3.561
M2.2×0.45 1.863 1.827 M5×0.5 4.606 4.560

○MS-RS-D recommendation for bar diameter

for metric external screws Unit : mm
recommended bar diameter
designation
Max Min
S0.5×0.125 0.410 0.396
S0.6×0.15 0.494 0.479
S0.7×0.175 0.575 0.559
S0.8×0.2 0.658 0.640
S0.9×0.225 0.741 0.720
Information
Technical

Technical-31

680
 16. Surface Treatment

Description of products
The best surface treatment is applied to each tap depending on the tapping purpose.
Characteristics and effectiveness of surface treatment are introduced at next section.

■Oxidizing

○This treatment was processed by using HOMO furnace being made by LEED AND NORTHUP company USA in 1938, and it is called HOMO treatment.
This treatment is also called vapor treatment and steam treatment. Through this treatment, Fe304 layer of blue black color is produced over the tool
surface.
○Oxidization treatment produces porous layer on tool's surface. This porous layer works as oil pocket to reduce friction, to avoid welding and to
improve the surface roughness of internal screw. Moreover, longer tool life is expected because the treatment reduces the remaining stress of HSS
tools.
○This treatment does not increase the hardness on tool surface. Using the furnace of YAMAWA original design and choosing the proper treatment
time, we have marked good result of oxidizing for YAMAWA HSS tools.
○Stainless steel and low carbon steel are the materials that are easy to get welding. We are applying this treatment to the special purpose taps for
these materials to get good result. Further due to the reduction of friction resistance, this treatment has good result for wide range of steel type
material.
○We combine oxidizing with nitriding for the taps designed for such steel and alloy tool steel. This double treatment wins good reputation of the
market.

■Thickness of oxide layer and the time of treatment ■Efficiency of oxide treatment

Cutting condition
Tap : SU-SP/M8×1.25/P2

Material : SUS304 (165~171HB)

Hole size : φ6.8mm

Tapping Length : 12mm (through hole)

Number of tapped holes
Thickness of oxide layer

Tapping Speed : 7.2m/min

Cutting oil : Non-water soluble oil

Tapping Machine : CNC tapping machine

SU (Bright) Oxide
(minute) treated
Treatment time
Information
Technical

Technical-32

681
 16. Surface Treatment
Description of products

■Nitriding

○In this treatment, we have Nitrogen and Carbon soak into the surface of HSS tools, and react with chemical of HSS material to produce hard nitride.
There are 3 method in the treatment, as composition gas method, salt bath nitride method and ion nitride method.
○Salt bath nitride treatment is shifted into gas nitride treatment method because of cyanic environmental pollution.
○The temperature of treatment is 500 to 550 degree. Hardness and depth of the treatment can be controlled by active nitrogen concentration and
reaction time.
○The high hardness of tool surface minimizes chemical attraction. Result is less welding and friction resistance. Great improvement is expected in
tool's performance.
○We have found out the best combinations of hardness and toughness through our treatment technology
○The nitriding treatment will be widely applicable to workpiece materials such as gray cast irons, special cast irons, aluminum diecastings with higher
silicone content, copper alloys, and resinoids (plastics), these materials produce small segmental chips and are very abrasive.
○We combine nitrogen and oxidizing for comparatively sticky material such as high carbon steel and refined alloy steel. This double treatment
improves the chipping resistance and have won good reputation.

■Depth and hardness of Nitride Surface Treatment ■Efficiency of Nitride Treatment

Cutting condition
Tap : Plug tap FC-O M8×1.25
Treatment A
Treatment B Material : FC250
Treatment C
Hole size : φ6.8mm
Tapping Length : 12mm (through hole)
Tapping Speed : 12m/min
Number of tapped holes
Surface hardness

Cutting oil : Water Soluble cutting oil (×20)

Tapping Machine : CNC tapping machine

surface FC-O Nitrided

Depth from the surface (Bright)
Information
Technical

Technical-33

682
 16. Surface Treatment

Description of products
■Hard coating

High speed cutting and hard-to-machine cutting are the recent technology. To meet this tendency, the hard layer coating by vapor deposition over
tool's surface has become popular. There are two coating methods, CVD and PVD. PVD is mainly used for tap.

■Physical Vapor Deposition

○Inside of the container of high vacuum, are heat vapor deposition materials. And we vapor deposit particles ionized by electric discharge on tool's
surface.
○Due to its low reaction temperature (lower than 500˚C), PVD makes little change in shape and hardness of HSS tools.
○We have adopted iron plating method, and are coating thin layer (1-4um) over our HSS and carbide tools. This layer processed by this method is
very high in its adherence and its wear resistance.

■The features and classification of coating

Classification Titanium nitride aluminum
Titanium nitride (TiN) Titanium carbonitride (TiCN) Hard chromium plating (CrN)
Features (TiAIN)
Vickers Hardness
Wear resistance Good Excellent Excellent Normal
Welding resistance Good Good Good Excellent
Heat resistance Good Normal Excellent Excellent
Acid resistance Good Normal Excellent Good
Slippery Good Excellent Good Excellent
Blue Dray
Color Gold Violet Silver
Violet
Carbon Steels Carbon Steels Stainless Steels Copper
Aluminum forging Hard Steels Cast Irons
Workpiece materials Stainless Steels
Aluminum forging
Cast Irons
Brass・Bronze
Note: Evaluation (tri-level) of characteristic features is just comparative of these four coatings, TiN, TiCN, TiAlN, and CrN, in the table. These coatings have great advantages of wear resistance, welding
resistance, and reduced friction resistance. The values of vickers hardness are also higher than the heat treatment or nitriding of HSS cutting tools from the table.

■The efficiency of TiN coating ■The efficiency of TiCN coating

Tapping condition Tapping condition
Tap : F-SL P2 M6×1 Tap : N-RS G7P P2 M6×1
Work piece : S45C (213~222HB) Work piece : ADC12
Number of tapped holes
Number of tapped holes

Hole size : φ5mm Hole size : φ5.54mm

Tapping Length : 14mm (through hole) Tapping Length : 14mm (through hole)
Cutting Speed : 30m/min Cutting Speed : 15m/min
Fluid : Water Soluble cutting oil Fluid : Water Soluble cutting oil
Machine : CNC tapping machine Machine : CNC tapping machine
Information
Technical

Bright TiN coated Bright TiCN coated

(F-SL)

Technical-34

683
 17. Carbide Taps
Description of products

Technological advances in machining automation and CNC machines and machining centers have helped improve the overall tapping process.
YAMAWA was quick to respond to evolving customer needs resulting from technological innovations.
We can now recommend carbide taps, which provide tremendous improvements in mass-production and in reducing costs. It is estimated that
carbide taps have 50 times more durability than HSS in tapping, when used properly. YAMAWA engineering believes the best carbide materials
suitable for taps are ultramicro grain tungsten carbide, or ultrafine grain carbide made of high cobalt.

■Features of Carbide Taps

(1)Excellent durability with high toughness is obtainable.

(2)High anti-friction features are provided by the material's high hardness and comparatively high stringyness, which ultimately results in a longer tool
life.
(3)Specially designed cutting angle and other dimensional features produce the internal threads with high tolerance accuracy and consistency.
(4)Under certain tapping condition, YAMAWA carbide taps can be used even for tapping hard-to-machine materials.

■Points to note during tapping with Carbide taps:

(1) Machine vibration, or run-out, can lead to Carbide tap chipping and premature failure. Tapping vibrations need to be kept to a minimum.
(2) Tap holder should be a rigid type for a Carbide tap. A holder attachment with axial float, or radial float tends to promote Carbide tap breakage and
chipping.
(3) The hole to be tapped must be located correctly and on center ; any centering off or non-straight drilled hole tends to cause Carbide tap breakage
due to deflection. Select correct hole depth with respect to tapping length (for blind hole only). It is especially important to prevent tap damage
from chip packing and bottom thrusting in blind hole tapping.
(4) Cutting lubricants - select grade of lubricant. Improper flow of coolant, or lack of sufficient amount of lubricant, or cooling can increase the
likelihood of Carbide tap chipping due to work material welding. Caution must be taken during dry machining to prevent chip welding to the tap.
(5) Work pieces - we provide Carbide taps with increased toughness, but Carbide taps are inferior to High Speed Steel (HSS) in the area of toughness.
As a matter of fact Carbide taps have limited application due to this difference in toughness to HSS.

■Commonly used material and cutting conditions.

Cutting Speed
Work Material Cutting Fluid (General recommendation) Cutting Fluid (JIS recommendation)
(m/min)
Ordinary Dry, light oil, water soluble oil Un-soluble oil, 2nd kind No.11 and 13
Water soluble oil, W 1st kind No.1,
Cast Iron Nodular Graphite Light oil, water soluble oil
W 2nd kind No.1
Malleable Water soluble oil
Aluminum Light oil, water soluble oil Un-soluble oil, 1st kind No.4-6
Un-soluble oil, 2nd kind No. 5-6
Copper Light oil, water soluble oil
Water soluble oil, W 1st kind No.1
Brass Light oil, water soluble oil
Copper Alloy
Phosphor Bronze Light oil, water soluble oil
Aluminum Alloy Mixed oil of lard oil and kerosene Un-soluble oil, 2nd kind No. 5-6
Die-Cast Water soluble oil, W 1st kind No.1
Zinc Alloy Mixed oil of lard oil and kerosene
Thermosetting Water soluble oil, air Water soluble oil, W 2nd kind No.3
Plastic
Thermo Plastic Water soluble oil, air
Hard Rubber Dry, air
Note : The table shows only general conditions. As for actual cutting operation, please consider the following points : (1) Machine Capacity, (2) Work piece(s), (3) Work Shape, (4) Setup (5) other factors.
Information
Technical

Technical-35

684
 17. Carbide Taps

■Toughness and Hardness of Cemented Carbide and HSS ■Chamfer wear and number of holes of Carbide taps and HSS taps

Description of products
Deflective Strength
(MPa) (HRA)
Hardness Cutting Condition
Tap : M5×0.8P4
Chamfer Length : 3
Machine : Machine with multi spindles
Hole Size : φ4.2mm
Thread Length : 10mm Through
Fluid : JIS W1-1
Workpiece : FC250

Indicator drop chamfer wear

HSS taps
Deflective Strength

Carbide taps

Hardness

P50 UF・A UF・B SKH51 SKH58

(SKH9) (AISI M7)
Number of holes
Cemented Carbide HSS

■Carbide Taps examples and comparison of tool life

Size
M2×0.4 M8×1.25 M6×1 M8×1.25 M10×1.25
Classification

Material Plastic with glass fibre ADC12 FC250 FC250 FC250

Workpiece
Part's name Electric Parts Car Parts Electric Parts Car Parts Car Parts

Tapping Hole.
φ1.6 Through φ6.7 Blind φ5.0 Blind φ6.7 Blind φ8.7 Blind
Thread condition
Condition
Tapping Length 4mm 18mm 10mm 16mm 18mm

Machine Special Machine Special Machine 4Spindles Machine Spindles Machine Special Machine

Condition
Cutting Speed 6.3m/min 8.5m/min 8m/min 6m/min 5.7m/min
of Use

Fluid Dry Water soluble Water soluble Water soluble Water soluble

CT Tap 10.000 75.400 53.000 18.860 38.500

Number
HSS Tap 200 1.000 1.000 300 500
of Holes
Comparison
50 75.4 53 62.9 77
of Life
Note : In above all situations, HSS taps are used standard ones. To use CT properly is capable of a long tool life.
Information

These datum have come from customers are useing CT taps.

Technical

Technical-36

685
 18. Pipe Taps Standard
Description of products

1. JIS Pipe Taps

The pipe thread standard (JIS B 0202,0203) was revised in 1982 to meet ISO standard. In the same year, JIS B 4445 (straight pipe thread taps) and JIS B
4446 (taper pipe thread taps) were also revised.
○A part of the pipe thread standard was revised in 1966 to meet ISO, but in the 1982 revision, the ISO standard was defined in the main book of JIS and
the old 1966 standard was defined in JIS Appendix. For Pipe Threads, which are specified in the main book of JIS and JIS Appendix, thread symbols are
different but the nominal size 1/8 to 6 inch are same. In the 1998 revision, the contents of the main book of JIS and JIS Appendix are not changed.
○ISO tap standard for pipe threads is different from the JIS tap standard in style, size and thread limit. Like the pipe thread standard, in JIS tap
standards for pipe threads, style, size and thread limits of ISO standard are specified in the main book of JIS and those of old JIS standard are in the
JIS Appendix. For ISO standard (style and size), please refer to the next page.
○Thread limits of Rp and G taps are the same as the ISO standard. The thread limit of Rc taps is the same as the JIS class 2 of PT taps shown in JIS
Appendix because Rc is not specified in the ISO standard. Therefore, both Rc taps and PT taps can be used interchangeably. For the relation
between thread limit of internal threads and tap thread limit, please refer to the table below.
○Pipe Taps standard was revised in 1987. And tap designations shown in JIS Appendix were changed to Parallel Pipe Thread Taps for PF, Taper Pipe
Thread Taps for PT, Parallel Pipe Thread Taps for PS.

■Symbol of Pipe threads

Type Classification Standard JIS (ISO) JIS Appendix Type

Internal Thread
Taper Thread
External Thread
Taper Thread
Internal Thread
Parallel Thread
External Thread
PF, A class
Internal Thread
PF, B class
Parallel Thread Parallel Thread
G, A class PF, A class
External Thread
G, B class PF, B class

■Relation of pitch diameter tolerance zone between thread and tap

Parallel Pipe Thread : JIS B 0202 Straight Pipe Thread Taps : JIS B 4445
Example.1-11 Taper Pipe Thread : JIS B 0203 Taper Pipe Thread Taps : JIS B 4446

JIS JIS Appendix JIS JIS Appendix

Taper Thread
Parallel Thread
Taper Thread※ Parallel Thread Taper Thread※ Parallel Thread
G PF R Rc Rp PT PS
Thread Tap Thread Tap Thread Thread Tap Thread Tap Thread Tap Thread Tap
3 Class
B Class

Basic Gauge Plane (31.770mm)

2 Class
A Class
A Class

A Class
B Class

B Class

3 Class
2 Class
Information
Technical

※ : In shown by converting the tolerance of radial direction to that of axial direction.

The thread tolerance of Taper Pipe Taps are specified by the gauge
plane and thread profile of addendum and dedendum.
Internal Thread External Thread

Technical-37

686
 18. Pipe Taps Standard

■Comparison of the thread limit of taper pipe tap

Description of products
Basic diameter position Basic diameter position Basic diameter position

ha : upper deviation

ha
P = 25.4/n

hd
n = Number of thread

hd : upper deviation
Taper
hd : lower deviation

Axis of tap

Unit : mm
Appendix (PT) Thread Limit
ISO (Rc)
Basic major PT Thread S-PT Thread ha hd
Norminal Number of
Dia. of
Size Threads※ Basic Diameter Basic Diameter Basic Diameter
Gauge Plane Thread Length Thread Length Thread Length Basic Size Tolerance Basic Size Tolerance
Postion Postion Postion
(μm) (μm)

/ 16
1
∼

/8
1 ∼

/4
1 ∼

/8
1 ∼

/2
1 ∼

/4
3 ∼

/4
1 ∼

/2
1 ∼

/2
1
∼

∼
Information
Technical

Note : JIS standard has 2 types of Taper pipe thread, PT and S-PT taps ISO standard has one type of Taper pipe thread Rc, which can substitute, PT and S-PT taps

※ : Threads per inch

Technical-38

687
 18. Pipe Taps Standard

■Comparison of the thread limit for straight pipe taps

Description of products

Unit : μm
The Thread Limit of ISO (G) The Therad Limit of Appendix of PF

Norminal Number of Pitch Major Dia Pitch Dia Minar Dia Major Dia Pitch Dia Minar Dia
Size Threads※ (mm)
Basic Size LT Basic Size UT LT Basic Size Basic Size LT Basic Size UT LT Basic Size UT
Tolerance UT Tolerance
(mm) (+) (mm) (+) (+) (mm) (mm) (+) (mm) (+) (+) (mm) (+)
/ 16
1

/8
1

/4
1

3/8
/2
1

/8
5

/4
3

/8
7

Not Specified
1/8
1/4
1/2
3/4

1/4
1/2
3/4

1/2 ※ : Threads per inch

UT : The upper deviation
LT : The lower deviation

■Comparison of the thread limit of taper pipe taps Unit : μm

The Thread Limit of ISO (Rp) The Therad Limit of Appendix of PS

Norminal Number of Pitch Major Dia Pitch Dia Minar Dia Major Dia Pitch Dia Minar Dia
Size Threads※ (mm)
Basic Size LT Basic Size UT LT Basic Size Basic Size LT Basic Size UT LT Basic Size LT
Tolerance UT UT Tolerance
(mm) (−) (mm) (−) (−) (mm) (mm) (−) (mm) (−) (−) (mm) UT (−)
/ 16
1

/8
1

/4
1

/8
3

/2
1
Not Specified

/4
3

1 /4
1 /2

1 /2
Information

※ : Threads per inch

Technical

UT : The upper deviation

LT : The lower deviation

Technical-39

688
 18. Pipe Taps Standard

2. American Pipe Thread Taps

Description of products
American standard pipe thread has various types and are complicated. We show their symbols and engagement of threads as follows.

■Pair groups of external thread and internal thread.

Standard Symbol Internal Thread Maiting Thread External Thread Maiting Thread

American Standard Taper Pipe Thread for General

Use

American Standard Straight Pipe Thread in Pipe

Couplings

American Standard Taper Pipe Threads for Railing

Pipe Threads, General Purpose Joints

(ANSI/ASME B1.20.1) American Standard Straight Pipe Thread for Free-

Fitting Mechanical Joints for Fixtures

American Standard Straight Pipe Thread for

Loose-Fitting Mechanical Joints with Locknuts

American Standard Straight Pipe Threads for Loose-

Fitting Mechanical Joints for Hose Couplings

Dryseal American Standard Taper Pipe Thread

Dryseal SAE Short Taper Pipe Thread

Dryseal Pipe Threads

(ANSI B1.20.3) Dryseal American Standard Fuel Internal Straight

Pipe Thread

Dryseal American Standard Intermediate Internal

Straight Pipe Thread

Note : These symbols correspond to the name of American pipe thread.

These threads are

(1) Thread angle is 60˚
(2) Taper of Taper Thread is 3/4" per foot.
(3) Fundamental height of triangle : H=Height of triangle thread profile H=0.866025P
(4) The difference between American Standard Pipe Thread for general use and Dryseal American Standard Pipe
・Crests and roots truncation of thread is different.
・The length of engagement for pipe thread is different by types.
・With regard to standard, Dryseal American Standard Pipe Thread is available in right hand.
In accordance with ANSI B 94.9, 4 types of pipe thread are specified in American Pipe Thread Standard.
Please refer to next page about the relation between taps and threads and about thread tolerance.
Information
Technical

Technical-40

689
 18. Pipe Taps Standard

○Classification of American pipe thread taps

Description of products

Designation Symbol Class Material Threads to be cut Range

Straight Pipe Thread Tap /8

1

Dryseal Straight Pipe Thread Tap /8

1 /4
3

Taper Pipe Thread Tap / 16

1

Dryseal Taper Pipe Thread Tap / 16

1

■Thread limit of American Pipe Thread Taps

○Straight pipe thread taps for (NPS) G Class
Max: Major Dia.

Min: Major Dia.

Max: Pitch Dia.

Min: Pitch Dia.

Minor Dia.
Max:

Unit : mm
Major diameter Pitch diameter Minor diameter※
Nominal Size
Max : Major Dia. Min : Major Dia. Tolerance Max : Pitch Dia. Min : Pitch Dia. Tolerance Max : Minor Dia.

※ : Above dimensions change depending on actually measured.

○Taper pipe thread taps (NPT) G Class

Tc (Max)
Tc (Min)

Fc (Max)
Fc (Min)

Number of thread

Fr (Max)
Tr (Max)
Tr (Min)

Fr (Min)
Information
Technical

Axis of tap
Taper

Technical-41

690
 18. Pipe Taps Standard

Unit : μm

Description of products
Crest Root
Nominal Size Tc Fc Tr Fr
Max Min Max Min Max Min Max Min

■Thread limit of Dryseal American Pipe Thread Taps

○Straight pipe thread taps (NPSF) G Class

Measurement Flank limit (deviation)

Flank limit (measurement)

Max: Major Dia.

Min: Major Dia.

Tr (measurement)

Tr (Max)

Max: Pitch Dia.

Min: Pitch Dia.

Max: Minor Dia.

Fr (Max)

Fr (measurement)
Fr (Max)

Unit : mm
Major diameter Pitch diameter Minor diameter※
Nominal Size
Max : Major Dia. Min : Major Dia. Tolerance Max : Pitch Dia. Min : Pitch Dia. Tolerance Max : Major Dia. Fr (Max) Tr (Max)

※ : Above dimensions change depending on actually measured.

Information
Technical

Technical-42

691
 18. Pipe Taps Standard

○Taper pipe thread taps (NPTF) G Class

Description of products

Fc (Max)

Tc (Max)
Tc (Min)
Measurement Flank limit (deviation) Fc (Min)

Flank limit (measurement) Number of thread

Tr (measurement)

Tr (Max)

Tr (Max)
Fr (Max)

Fr (measurement)
Axis of tap
Fr (Max) Taper

Unit : μm
Crest Root
Nominal Size Tc Fc Tr Fr
Max Min Max Min Max Min
Information
Technical

Technical-43

692
19. Features of MC-Helical Thread Mills

○Various nominal diameter internal threads of the same pitch can be produced with the same thread mills.

Description of products
○The same mill can be used for both right-hand and left-hand internal threads.
○Chips become very minute, and troubles caused by chips are rarely expected.
○Internal threads of large diameter are obtainable even with low power machines.
○Size control (undersize or oversize) is easy on programming process. Thus, internal threads with voluntary thread limits can be obtained.
○When using MC-Helical threads mills for producing taper pipe threads, the threads are produced in a perfect cutting circle, and no stop
marks which are inevitable in taper pipe threads tapping and high quality pressure-tight joint can be made.

Right hand screw

Central axis of cutters Central axis of cutters

Central axis of work material Climb Conventional Central axis of work material
milling for milling for
through hole blind hole

Left hand screw

Central axis of cutters Central axis of cutters

Information
Technical

Central axis of work material Conventional Climb milling

Central axis of work material
milling for for blind hole
through hole

Note : Basically, conventional milling is recommended due to excellent chip ejection. However, climb milling is recommended in the case of poor horse power and poor rigidity of the machine.

Technical-44

693
 19. Features of MC-Helical Thread Mills

■Comparison of internal threads cut by helical cuttter and by PT tap

Description of products

■By tap
When PT tap cuts internal threads, the tap cuts the threads with all cutting edges and the
tap reverses from the position where each cutting edge on lands sticks into the material
wall of internal threads. This results in the stop line due to a step caused by this sticking.

■By helical cutter

Due to the thread cutting of 3 axis movement without reversing, the internal thread has
no stop line.

■Selection of tool diameter against the size of the internal screw

When cutting internal screws with MC-HLC, please choose the tool which diameter is
smaller than 70% of internal threads diameter. The cutter of using larger outside diameter is preferable due to its high rigidity. But thread milling cutters
do not have screw lead. Please select thread milling cutters by referring to the shape & size table.

■Cutting Condition
○Carbide helical cutter ○HSS helical cutter
Cutting Speed Cutting Speed
Material Feed per tooth (mm/t) Material Feed per tooth (mm/t)
(m/min) (m/min)
Stractual Steel 50∼250 0.02∼0.1 Stractual Steel 25∼45 0.02∼0.05

Carbon Steel 50∼200 0.02∼0.1 Carbon Steel 20∼40 0.02∼0.05

Alloy Steel 30∼180 0.02∼0.1 Alloy Steel 15∼30 0.02∼0.05

Tool Steel 30∼150 0.02∼0.1 Tool Steel 10∼15 0.02∼0.04

Stainless Steel 30∼200 0.03∼0.1 Stainless Steel 10∼15 0.03∼0.05

Cast Iron 50∼150 0.03∼0.15 Cast Iron 30∼50 0.03∼0.08

Aluminum, Aluminum Alloy 50∼300 0.03∼0.15 Aluminum, Aluminum Alloy 50∼90 0.03∼0.05

Copper, Copper Alloy 50∼180 0.03∼0.15 Copper, Copper Alloy 40∼80 0.03∼0.05

■Feeding speed

Feeding speed is decided by the characteristic of work materials. Feeding

speed is an important factor because machining time, thread finish and Feed speed of fool
tool durability are getting influenced by the feeding speed.
F = fz・Z・n・(Dc-d)/Dc (mm/min)
In the material of low tensile strength, feed per tooth can be set up rather
large. However, if you set up feed per one tooth too large, thread milling fz : Feed per tooth
z : Number of tooth
cutters can cause deflection and may badly cause thread limit. n : Spindles RPM
d : Diameter of tool
Dc : Nominal size of internal thread

■Incision of cutters
Side of
Generally, incision of cutter is decided by the machine programming in internal threads

which the machine enables the cutter to cut the thread height in one
revolution. MC helical cutters is so designed that its minor diameter does
not cut and the same bored hole size as that for cutting tap is adopted.
Information
Technical

Side of milling cutters

Technical-45

694
 19. Features of MC-Helical Thread Mills

Description of products
─Metric thread ─Metric thread

[ Minor diam basis] [ Tool basis]

Tool incision Tool transverse

where,
: Nominal size of internal threads
: Basic minor diameter of internal threads
: Minor diameter before cutting
: Outside diameter of tool
: 0.866025P
: Pitch
: Tolerance of pitch diameter for producing internal thread
: Shrinkage after cutting
(Set up in the middle of pitch diameter tolerance)

: Difference between of basic thread profile and O.D. of the cutters.

■Approaching and leaving to and from work material

On approaching and leaving to and from work material, the cutter must always be traversed in
helical interpolating movement so that the cutter enables smooth cutting in and out. And it is
necessary to cut the material gradually by the lead of screw thread. Otherwise, threads can be
thinned.

Initial cutting A＜B

Information
Technical

Technical-46

695
 20. Selecting different tap holder combinations by machine feed system
Description of products

The function of machine feed systems

Fully synchronous feed (Rigid) tapping system

Spindle revolution and machine feed are synchronized, a perfect thread lead
and feed per revolution are realized.

Feed by lead screws

A better-feed condition is realized because the tap is fed by a master lead

screw shaft that has the same thread lead as this tap.

Feed by gear

The tap is fed at the same thread lead by a combinations of gears. This creates
a better-feed to thread lead condition.

Asynchronous feed system

Best used when the spindle rotation and the machine feed are set indepen-
dently, especially, if the machine feed value cannot be accurately predicted to
be that of the tap thread lead.

Hydraulic or Pneumatic pressure feed system

Feed is controlled by a pressure regulation system which normally results in an

inaccurate feed per revolution compared to the tap thread lead.

Manual feed

Feed is controlled by operator which is difficult to keep a stable amount of feed

Information
Technical

per revolution.

Technical-47

696
 20. Selecting different tap holder combinations by machine feed system

Description of products
Characteristics of tap self-guiding behavior
Holders aspects
r=tap’s radius, s=thread relief, t=margin width

Eccentric thread relief

(no width of margin)

Compression Tension

Spring direction

Completely rigid holder type

Tap characteristics ; high cutting performance and machin-
ing performance, with little to no self-guiding features.
The tap is held with no axial or radial Operation ; A fully synchronous machining system with fixed
adjustment in the collet and holder. rigid holder is needed.
Example : "High speed tapping" and "fully synchronous
tapping."

Con-eccentric thread relief

(margin and thread relief)

Adjustable spring floating holder

(Tension & Compression)
Tap ; High level of self-guidance due to suitable tap diameter
margin and thread relief. The combination of nice portion of
margin and chamfer relief helps to make appropriate tap guidance.
Machine feed and tap's thread lead
errors are corrected by two types of
spring system in the holder, the axial
tension direction of the tap and the Concentric (No relief)
axial compression direction of the tap.
Information
Technical

Tap ; A full thread land stays in contact with the thread major
diameter at all times. Tap has no thread relief on major
diameter, creating a high level of self-guidance even with
unbalanced feeding conditions.

Technical-48

697
 21. The common mechanics for a tap to cut oversize on an internal thread
Description of products

1. Run out, misalignment and tap cutting non perpendicular to holes Over-cutting at radial direction

Tool run out during tapping Misalignment during tapping Tapping a non-parallel or non-perpendicular
thread to the axis of the hole.
Holder needs to be Axis of tapping process Verification of
holder
adjusted. Tapping with holder
and bored hole should
holder holder
prepared hole
run out can be observed be lined up correctly. condition.
and checked when idle The use of adjustable
running. Chuck needs holder with floating
to be adjusted-Tapping features will reduce this
with run out could be Lateral force problem.
observed and checked
Solutions
by idle running.

misalignment

Run out

The tap normally follows the bored hole except when the tap cuts too large at the beginning of the hole from tap
run out, misallignment of the tap is to the bore diameter or the bore is out of parallelism to the thread axis. These
conditions cause the tap to cut over size at the beginning of the thread and cut smaller as the thread continues.

Excessive-cutting in the radial direction Normal internal threads

Not Go gauge

Over sized Normal Not Go

internal threads internal gauge internal threads
at the beginning Not Go gauge
of the bore threads

2. Using a tap not suitable for the operation or a tap with a dull cutting edge may cause galling which results in over-cutting. Over-cutting caused by galling and excess cutting

Using an incorrect tap for a specific workpiece material Tapping process with dull edge
can cause problems
Abrasion Welding Chipping
Select the correct Tap Flank
・Straight fluted tap
・Spiral fluted tap
・Spiral pointed tap
・Roll tap
Parallel
【Abrasion】 wear 【Welding】 【Chipping】

Selection of correct taps by material being tapped is

strongly recommended. Proper use of cutting oil, confirmed value to establish tool life constant

Incomplete
A torn thread is observed on all surfaces of internal thread
Over-cutting caused by
thread, the flank angles, the major diameter and the galling and excess feeding
minor diameter. When this situation is continued, an Incomplete
over-cutting of the internal thread occurs, there are thread
deformed threads, there are interrupted threads, and
finally it leads to over size cutting of internal thread.

Incomplete
thread
Information

Not Go gauge
Technical

Technical-49

698
 21. The common mechanics for a tap to cut over size on an internal thread

Description of products
3. Tapping with an improper feed condition over-cutting at axial direction

The main reasons for producing an incorrect thread

At cutting edge b1, cutting chamfer of the tap

Workpiece Cutting part by b1

「Excessive-cutting of the thread

with excessive feeding」 Not Go gauge

Tap A clearance gap is created at the

back frank of thread. More material
is cut at front frank than at the back
flank creating an incorrect threads
Position of thread after the tap rotates 1 turn.

Tap Cutting advancement (b1) and thread advancement of cutting

face (c2) are misaligned creating the distance of excessive feeding A.

Distance of
excess feeding

Workpiece

Cutting trace by b1

Tap

Thread position after the tap rotates 2 turns.

Tap cutting chamfer (c3) is misaligned and the distance of

excess feeding B and cutting chamfer (d3) is misaligned to
create the distance of over feeding A+B.
Cutting situation

Workpiece Distance of
excess feeding

Tap
「over-cutting thread by too slow
The position of thread after 3 rotations of tap. feeding」

The thread continues to misalign until the distance of the

thread lead is in error from excessive feeding C. This condition creates just the
opposite of excess feeding or over-
Cutting situation cutting internal thread. A clearance
Not Go gauge
gap is created at the front frank and
extra material is cut at back frank.
Distance of
Workpiece excess feeding

Reasons for over-cutting during

tapping process (overview)

Tap The tap mounting condition in the holder.

The condition of bored hole.
Solutions
Feed adjustment is strongly recommanded. The cutting oil selection.
＊(Use of fully synchronous feed system and fixing holder) Incorrect adjustment of feed balance.
Information

Selecting the correct tap by material being

Technical

When using machine that do not have the functions

ahown, such as drilling machine. cut from the tap selection section.

＊The correct balance of main spindle adjustment is

strongly recommended.
＊Use an axial/radial floating holder for its adjustment.

Technical-50

699
 22. Trouble Shooting
Description of products

Troubles Breakage Excessive wear

Check point
Prevent excessive Prevent clogging of chips Tap Workpiece Tap
Segments cutting torque

●Use workpiece which has ○Use workpiece which has

even structure and hardness. even structure and hardness.
Hardness

●Pay attention for tapping position and material thickness. ●Pay attention for tapping
position and material thick-
Shape ness.

Workpiece
◎Provide bigger bored holes. ⃝Provide bigger bored holes.

●Provide countersinking on
●Prevent work hardening. hole entrance.

⃝Prevent work hardening.

Bored hole
◎Provide deeper tapping hole.

●Prevent slanting of hole.

●Avoid inconsistent feed.

Machine ●Adjust feed stroke.

●Use tap holder of floating type.

Jigs, Holders ◎Use tap holder with torque

limiter.

○Reduce cutting speed. ○Reduce cutting speed.

Cutting condition

●Use the other cutting oil ●Provide proper timing for changing or filling-up of cutting oil.
which prevents cold welding.
●Prevent mixing of other oil into cutting oil.
●Use non soluble type cutting
oil. ●Use other cutting oil which prevents cold welding.
Lubricant
●Use cutting oil of non soluble type.

●Adjust flow of cutting oil and method of lubrication.

●Remove unnecessary chips

during tapping.
On process ●Provide bigger space for
chips disposal.

●Use PO tap(through hole).

Selection ●Use SP tap(blind hole).

●Use Roll tap.

●Provide bigger chiproom. ●Change material of taps. ●Use set tap.

●Provide proper hardness on ●Change material of taps.

taps.
●Provide proper hardness on
taps.
Tap Design
●Reconsider length of cutting chamfer. ●Reconsider length of cutting chamfer.

●Use set tap. ●Provide nitride on taps.

●Be careful about burning during re-sharpening. ●Be careful about burning during re-sharpening.
Information

Re-grind ●Provide proper land. ●Increase re-sharpening frequency.

Technical

◎ : Most suitable solution  ○ : Second most suitable solution

Technical-51

700
 22. Trouble Shooting

Description of products
Undersize cutting of internal thread Bad surface, surface damaged

Improve cutting Selection and design of tap Work material Improve cutting Prevent welding Check cutting condition
performance performance

●Check workmaterial. ●Provide proper hardness on

workpiece material.

●Pay attention for tapping ●Pay attention for tapping

position and material thick- position and material thick-
ness. ness.

●Adopt bigger tapping hole.

●Prevent work hardening of

material.

●Prevent work hardening. ●Provide bigger bored holes. ⃝Prevent slanting of hole.

○Feed according to pitch.

●Use the tap holder of floating type.

●Prevent vibrating of axis of tap
●Prevent centering-off with
work piece.

●Reduce cutting speed.

●Provide proper timing for changing or filling-up of cutting oil.

●Prevent mixing of other oil into cutting oil.

●Use other cutting oil which prevents cold welding.

●Use cutting oil of non soluble type.

●Adjust flow of cutting oil and method of lubrication.

●Remove unnecessary chips

●Provide Nitride on taps. ◎Use oversiza taps. ●Use spiral pointed taps ◎Provide oxide coating on ◎Use oil hole taps.
(for through hole). taps.

○Provide larger cutting angle. ●Adjust relief angle on cutting ◎Provide larger cutting angle. ●Change of no. of flutes on ●Reconsider length of cutting
chamfer. taps. chamfer.
●Adjust relief angle on cutting
chamfer.
○Provide thread relief.
○Provide more narrow margin.

●Increase re-sharpening ●Provide better surface fini-

frequency. shing on flutes.
Information

●Increase re-sharpening frequency.

Technical

●Provide precise re-sharpening.

●Be careful about burning during re-sharpening.

Technical-52

701
 22. Trouble Shooting
Description of products

Troubles Over-cutting of internal thread

Check point
Prevent uneven in Prevent over Prevent welding Check cutting condition Prevent unbalance
Segments feed of tap cutting on thread on entering

●Use workpiece which has

even structure and hardness.
Hardness

Shape

Workpiece
●Provide bigger hole. ●Prevent slanting of hole. ●Provide countersinking on
the hole entrance.

Bored hole

●Adjust a feed.

Machine ◎Feed according to pitch.

○Use tap holder of floating ◎Prevent vibrating of axis of tap.

type. ○Prevent centering-off with
Jigs, Holders work piece.
●Use tap holder of floating type.

●Reduce cutting speed.

Cutting condition

●Use other cutting lubricant

which prevents cold welding.

●Check the viscosity.

Lubricant

On process

◎Provide oxide surface treatment.

Selection ⃝Use tap with oil hole.

⃝Provide small cutting angle. ●Provide short thread length. ●Reconsider number of flules ●Reconsider number of flules
of tap.
●Adjust chamfer relief angle.

Tap Design ◎Check the width of thread

margin.

●Remove burrs on teeth after ●Provide precise re-sharpening. ◎Care for vibration.
re-grinding.
Information

Re-grind
Technical

●Provide proper land.

◎ : Most suitable solution  ○ : Second most suitable solution

Technical-53

702
 22. Trouble Shooting

Description of products
Chipping Tapping operation

Prevent clogging of chips Prevent excessive Improve tapping method Tap Prevent clogging of chips Tap
cutting torque

●Use workpiece material which

has even structure and hardness.

⃝Pay attention for tapping ●If possible, use finer pitch tap or shorter tapping length.
position and material thick-
ness.

Provide deeper tapping hole ◎Provide bigger tapping hole. ●Prevent slanting of holes. ○Reduce cutting speed.
(Blind hole).
◎Provide deeper tapping hole
●Prevent work hardnening.
(Blind hole).

●Provide countersinking on hole the entrance.

●Avoid inconsistent feed.

⃝Use tapping holder with ●Prevent centering-off with ●Use the tap holder of floating type.
torque limiter. workpiece. ●Prevent vibration of axis of tap.
●Prevent vibration of axis of tap. ●Prevent centering-off with
●Use the tap holder of floating type. workpiece.

●Reduce cutting speed.

●Reduce cutting speed.

●Use the other cutting oil ●Check the viscosity.

which prevent cold welding.

●Remove unnecessary chips ●Remove unnecessary chips during tapping.

during tapping.

●Provide bigger space for chip ●Provide bigger space for chip disposal.
disposal.

●Use PO taps (Through hole). ●Use PO taps (Through hole).

●Use SP taps (Blind hole). ●Use SP taps (Blind hole).

●Use Roll tap. ●Use Roll tap.

●Provide bigger chip room. ●Change material of tap. ●Provide bigger chip room.

●Provide smaller cutting angle.

●Reconsider length of cutting chamfer.
●Provide proper hardness.
◎Use oil hole tap.

●Reconsider length of cutting chamfer.

●Provide shorter thread length to tap.
●Reduce cutting speed.
●Adjust relief angle on cutting chamfer.
Information

●Be careful about burning during re-sharpening.

Technical

Technical-54

703
 23. Center Drills
Description of products

Center Drills are the tool for making center hole. Center Drills are also used for positioning before drilling, and for chamfering of the hole.

Shank portion Chamfering portion

■Names of each part
Drill diam. Drill portion

Shank diam.
Drill length
Overall length

■Shape of center hole and center

Type A (60°) Center hole & 60°center Type B (60°) Center hole & 60°center Type A (90°) Center hole & 90°center Type R Center hole & 60°center

■Advantage of Type B Center holes

Avoid burrs around the hole
Avoid roughness surface
Avoid scar or distortion
resulting from a blow

of work piece

Note : Advantage of Type B center holes : B type center drill protect the 60° conical bearing surface from scar or distortion resulting from a blow, roughness of workpiece surface or
burrs around the hole.

■Advantage of Type R Center holes

Angle of center hole is higher than Angle of center hole is lower than Center hole and center are misaligned.
that of center. that of center.

A type

R type
Information
Technical

Note : R type center hole stably holds the center. It also some of advantage of B type center hole.

Technical-55

704
24. Table of recommend centering condition

Description of products
■Tabie of recommend centering condition.

HSS (PE-Q PE-90˚)

Work Soft structural steels Carbon steels Alloy steels Stainless steels Aluminum alloy casting
material

Cutting speed

Diameter Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution

HSS+TiCN (PE-Q-V PE-90˚)

Work Soft structural steels Carbon steels Alloy steels Thermal refined steels Stainless steels Aluminum alloy casting
material

Cutting speed

Diameter Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution

Carbide+TiAIN (C-PE-Q-V PE-90˚)

Work Soft structural steels Carbon steels Alloy steels Thermal refined steels Stainless steels Aluminum alloy casting
material

Cutting speed

Diameter Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution Revolution Feed per revolution

1. Above Condition done by Water Soluble oil.

2. 20% lower feed is recommended when centering prosess to inclined plane.
3. 20% lower feed is recommended in the case of long shank point drills.
Information
Technical

Technical-56

705
 24. Tabie of recommend centering condition

■Reference of drilling condition for Center drills (HSS)

Description of products

Reference table of cutting speed and feed per revolution (when substrate is HSS)

・Drilling speed (Cone diameter at the larger end)

Workpiece materials Drilling speed Drill diameter Feed per revolution

Low carbon steels
Carbon steels
Alloy steels
Stainless steels
Cast iron

■Reference of drilling condition for Center drills (Carbide)

Reference table of cutting speed and feed per revolution (when substrate is Carbide)

・Drilling speed (Cone diameter at the larger end)

Workpiece materials Drilling speed Drill diameter Feed per revolution

Low carbon steels
Carbon steels
Alloy steels
Stainless steels
Cast iron

■Reference of drilling condition for NC-SD-V

Reference table of drilling speed, feed per revolution

・Drilling speed (Tool diameter)

Workpiece materials Drilling speed Tool diameter Feed per revolution

Low carbon steels
Carbon steels
Alloy steels
Alloy tool steels
Stainless steels
Cast iron
Aluminum

■Reference of chamfering condition for Countersinks

Reference table of drilling speed, feed per revolution

・Drilling speed (Tool diameter)

Drilling speed Feed per revolution
Workpiece materials Tool diameter
Single edge Multiple edges Single edge Multiple edges
Low carbon steels
Carbon steels
Alloy steels
Alloy tool steels
Stainless steels
Cast iron
Aluminum
Information
Technical

Technical-57

706
25. Thread Series

■Metric Threads

Production data
Unit : mm
Nominal Dia. Pitch※

Column Column Column Coarse Fine

1 2 3

Information
Technical

※ : Please select the first column by priority. And select second column and third column if necessary.

Technical-58

707
 25. Thread Series

■Unifined Threads ■Conversion Table

Production data

Size Nominal Dia. Threads per inch

Column Column Coarse Fine Extra Fine Constant pitch series
inch Threads per inch Pitch (mm)
1 2
(25.4mm)

/
14

/
5 16

/
38
7/ 16
1/ 2
9/ 16
5/ 8

/
11 16

/
34

/
13 16

/
78

/
15 16

1
11/ 16
11/ 8
13/ 16
11/ 4
15/ 16
13/ 8
17/ 16
11/ 2
19/ 16
15/ 8
111/ 16
13/ 4
113/ 16
17/ 8
115/ 16
2
21/ 8
21/ 4
23/ 8
21/ 2
25/ 8
23/ 4
27/ 8
3
31/ 8
31/ 4
33/ 8
31/ 2
35/ 8
33/ 4
37/ 8
4
41/ 8
41/ 4
43/ 8
41/ 2
45/ 8
43/ 4
47/ 8
5
51/ 8
51/ 4
53/ 8
51/ 2
55/ 8
53/ 4
57/ 8
6
※ : Please select the first column by priority. And select second column and third column if necessary.

General size list of metric trapezoidal threads

Unit : mm
Information
Technical

When the tap for the trapezoidal threads not listed in the catalogue is required, please contance Yamawa sales.

Technical-59

708
26. Basic profile of threads

■Metric Screw Threads ■Unified Screw Threads

Production data
Internal Internal
Thread Thread

External External
Thread Thread

d1 or D1
d2 or D2

d1 or D1
d2 or D2
d or D

d or D
Threads per inch

■Whitworth Screw Threads ■Screw Threads for Sewing Machine

Internal Internal
Thread Thread

External External
Thread Thread

d1 or D1

d2 or D2
d1 or D1

d2 or D2

  D1’ 
  D1’ 

d or D
d or D

Threads per inch Threads per inch

■Miniature Screw Threads ■Parallel Pipe Threads

Internal
Internal Thread
Thread

External External
Thread Thread
d1 or D1
d2 or D2
d1 or D1

d2 or D2

d or D
d or D

Note : This figure rounds off 0.320744H.

Threads per inch

■Taper Pipe Threads ■Taper Pipe Threads (Parallel)

Internal
Thread
Internal
Thread

read
External Th
Information
Technical

Central axis line of thread Central axis line of thread

Threads per inch Threads per inch

Technical-60

709
 26. Basic profile of threads

■American Standard Taper Pipe Threads

Production data

Truncation Unit : mm
Threads
Section fc=fr
per inch

Internal
Thread Threads per inch

Central axis
External Thread line of thread

■Dryseal American Standard Taper Pipe Threads

Truncation Unit : mm
Threads
Section fc fr
per inch

Internal
Thread Threads per inch

Central axis
line of thread
External Thread

■Metric Trapezoidal Screw Threads ■29˚ Trapezoidal Screw Threads

Internal
Thread

Internal
Thread

External Thread

External Thread
d2 or D2
d1 or D1

d2 or D2

d or D

D1
d1

D
d
Information
Technical

Threads per inch

Technical-61

710
27. Symbols for Standard Threads

■Japan

Production data
Thread symbols Kinds of threads Related Standards
Metric screw threads
Miniature screw threads
Unified threads, Coarse series
Unified threads, Fine series
Metric Trapezoidal screw threads
Taper external pipe threads (JIS main book)
Taper internal pipe threads (JIS main book)
Parallel internal pipe threads (JIS main book)
Parallel pipe threads (JIS main book)
Parallel pipe threads (JIS Appendix)
Taper pipe threads (JIS Appendix)
Taper pipe threads (Parallel) (JIS Appendix)
Screw threads for rigid metal thin-walled conduit and fitting
Screw threads for rigid metal thick-walled conduit and fitting
Cycle threads
Screw threads for sewing machine (2001.2.20repeal)
Electric socket and lamp-base threads
Tire valve threads of automobile
Tire valve threads of cycle

■ISO
Thread symbols Kinds of threads Related Standards
ISO Metric threads
ISO Miniature screw threads
ISO Metric trapezoidal screw threads
ISO Unified threads, coarse series
ISO Unified threads, fine series
ISO Unified threads, extra fine series
ISO Unified threads, constant pitch series
Unified threads (MIL Standard) coarse
Unified threads (MIL Standard) fine
Unified threads (MIL Standard) extra fine
Unified threads (MIL Standard) constant pitch series
Metric threads, MIL Standard
Taper external pipe threads
Taper internal pipe threads
Parallel internal pipe threads
Parallel pipe threads
Glass container threads
Tire valve threads
Information
Technical

Technical-62

711
 27. Symbols for Standard Threads

■America
Production data

Thread symbols Kinds of threads Related Standards

Information
Technical

Technical-63

712
 27. Symbols for Standard Threads

Production data
■British※
Thread symbols Kinds of threads Related Standards

※ : We left out the symbols after ISO standard was adopted.

■German※
Thread symbols Kinds of threads Related Standards

※ : We left out the symbols after ISO standard was adopted.

Information
Technical

Technical-64

713
 28. Cross chart of thread cutting tool standard
Production data

Tap and Die names JIS JSCTA ISO ANSI BS DIN

General specification
Measuring method
Technical requirement
Thread limit (Metric)
Thread limit (Pipe)
Hand taps (Metric coarse)
Hand taps (Metric fine)
Hand taps (Unified coarse)
Hand taps (Unified fine)
Hand taps (Parallel pipe thread)

Hand taps (Taper pipe thread)

Hand taps (American parallel pipe thread)
Hand taps (American taper pipe thread)
Hand taps (American dryseal parallel pipe thread)
Hand taps (American dryseal taper pipe thread)

Nut taps (Metric coarse)

Nut taps (Metric fine)
Nut taps (Unified coarse)
Nut taps (Unified fine)
Machine taps (Metric coarse)

Machine taps (Metric fine)

Bent shank taps (Metric coarse)
Bent shank taps (Metric fine)
Bent shank taps (Unified coarse)
Bent shank taps (Unified fine)

Long shank machine taps (Metric thread)

Long shank machine taps (Inch thread)
Spiral pointed taps
Spiral fluted taps
Shell taps (Metric thread)

Pulley taps
Thread Forming taps
Blanks for carbide taps
Thread cutting round dies (Metric coarse, Adjustable)
Thread cutting round dies (Metric fine, Adjustable)

Thread cutting round dies (Metric, Solid)

Thread cutting round dies (Unified coarse adjustable)
Thread cutting round dies (Unified fine adjustable)
Thread cutting round dies (Unified thread)
Thread cutting round dies (Parallel pipe thread)

Thread cutting round dies (Taper pipe thread)

Hexagon dies

Symbols : Organization names

ISO : International Organization for Standardization ANSI : American National Standards Institute
JIS : Japanese Industrial Standards Committee BS : British Standards Institution, UK
JSCTA : The Japan Solid Cutting Tools’ Association DIN : Deutsches Institiut fur Normung
Information
Technical

Technical-65

714
29. Hardness conversion table

■Conversion table from Rockwell C hardness of steel. (Approximate)

Production data
Brinell Hardness Rockwell Hardness※2 Rockwell Superficial Hardness
Rockwell Rockwell
Vickers Shore Tensile
C Scale C Scale
Hardness Hardness Strength
Hardness Tungsten Hardness※2
Standard ball A scale B scale D scale 15-N scale 30-N scale 45-N scale MPa※1
Carbide ball

HRC HV HB HRA HRB HRD HS15N HS30N HS45N HS − HRC

Information
Technical

※1 : 1Mpa=1N/mm2
※2 : In above table, numbers in parenthesis are only for reference.
This table is abstracted from SAE J 417.

Technical-66

715
 30. Conversion table from inch to millimeter

■Conversion table from inch to millimeter

Production data

Designation
Fractional Decimal

/
1 64

/
1 32

3/ 64

1/ 16
5/ 64

/
3 32

/
7 64
1/ 8
9/ 64

5/ 32

/
11 64

/
3 16

/
13 64

/
7 32

/
15 64

/
14

/
17 64

/
9 32

/
19 64

/
5 16

/
21 64

/
11 32

/
23 64

/
38

/
25 64

/
13 32

/
27 64

/
7 16

/
29 64

/
15 32

/
31 64

/
12

/
33 64

/
17 32

35/ 64

/
9 16

/
37 64

/
19 32
39/ 64
5/ 8

/
41 64

/
21 32

43/ 64
11/ 16
45/ 64

/
23 32

/
47 64

/
34

/
49 64

/
25 32

/
51 64

/
13 16

/
53 64

27 / 32

55/ 64

/
78

/
57 64

/
29 32

/
59 64
15/ 16
Information
Technical

/
61 64

/
31 32

63/ 64

Technical-67

716
 31. Chemical Component table of work materials
Production data

The name of work materials Chemical Composition (%)

and material Symbols

Carbon steels Low carbon

for machine steels
structural use

Medium
carbon steels

High
carbon steels

Alloy steels Chromium

for machine Molybdenum
structural use Steels

Nickel
Chromium
Steels

Chromium
Steels

Nickel
Chromium
Molybdenum
Steels
Information
Technical

Technical-69

718
 31. Chemical Component table of work materials

Production data
Mechanical Property of Standard test block
Chemical Composition (%)
Tensile strength
Hardness Heat treatment of standard test block
others

normalizing

normalizing

normalizing

normalizing

normalizing

water hardening air hardening

normalizing

water hardening air hardening

normalizing

water hardening air hardening

normalizing

water hardening air hardening

normalizing

water hardening air hardening

Oil hardening
Oil hardening
tempering

Oil hardening air hardening

tempering

Oil hardening air hardening

tempering
Oil hardening
Water hardening
tempering
Oil hardening air hardening

Oil hardening
Oil hardening
tempering
Oil hardening
Oil hardening
tempering

Oil hardening air hardening

tempering

Oil hardening
Oil hardening
tempering
Oil hardening air hardening
tempering
Information

Oil hardening
Technical

Oil hardening
tempering
Oil hardening air hardening
tempering

Technical-70

719
 31. Chemical Component table of work materials
Production data

The name of work materials Chemical Composition (%)

and material Symbols

Alloy steels Nickel

for machine Chromium
structural use Molybdenum
Steels

Tool steels Chromium

Tool steels

Alloys Tool
steels

Stainless Austenite type

steels

Martensite
type

Ferrite type

Precipitation
hardening
Cast steels Carbon steels SC360
Cast steels
SC410

SC450

SC480

Stainless steels
casting

Steel casting
for high
temperature
and high
Information

pressure
Technical

Steel casting for

welded structure

Technical-71

720
 31. Chemical Component table of work materials

Production data
Mechanical Property of Standard test block
Chemical Composition (%)
Tensile strength
Hardness Heat treatment of standard test block
others

oil hardening air hardening

normalizing air hardening

Oil hardening
Oil hardening
tempering

annealing

annealing

annealing

annealing

annealing

annealing

annealing

annealing

annealing

annealing

annealing

annealing

solution treatment

annealing

annealing

normalizing

solution treatment

annealing, normalizing,
or normalizing, tempering

solution treatment

annealing, normalizing,
Information
Technical

or normalizing, tempering

Technical-72

721
 31. Chemical Component table of work materials
Production data

The name of work materials Chemical Composition (%)

and material Symbols

Cast irons Gray iron

castings

Tough cast Spheroidal

irons graphite
Ductile cast Cast irons
irons

High carbon chromium

bearing steels

Free cutting carbon steels

Rolled steels for general

structure

Cold-reduced carbon steel

sheets
Information
Technical

Technical-73

722
 31. Chemical Component table of work materials

Production data
Mechanical Property of Standard test block
Chemical Composition (%)
Tensile strength
Hardness Heat treatment of standard test block
others

spheroidizing

Standerd thermal refining

Information
Technical

Technical-74

723
 31. Chemical Component table of work materials
Production data

The name of work materials Chemical Composition (%)

and material Symbols

Copper Oxygen free high

conductivity copper
tough pitch
copper
Phosophor
deoxidized
copper

Brass Brass remaining

remaining

remaining

Free cutting remaining

brass
remaining

Bras s casting CAC201 11.0 17.0

CAC203 58.0 64.0 30.0 41.0

Bronze casting CAC401

CAC403

CAC406

Aluminum Aluminum
alloy rolling material

remaining

remaining

remaining

remaining

remaining

Aluminum
alloy casting remaining

remaining

remaining

remaining
Information
Technical

Aluminum remaining
alloy diecasting
remaining

Technical-75

724
 31. Chemical Component table of work materials

Production data
Mechanical Property of Standard test block
Chemical Composition (%)
Tensile strength Heat treatment of
Hardness
others standard test block
HV /
14

HV /
14

HV /
14

HV /
14

HV /
14

HV /
14

HV /
14

/
14

/
14

impurity

impurity

impurity

annealing

thermal refining

annealing

annealing

thermal refining

annealing

thermal refining

annealing

annealing

about casted

about

about casted

about

about casted

about

about casted

about
Information
Technical

Technical-76

725
 31. Chemical Component table of work materials
Production data

The name of work materials Chemical Composition (%)

and material Symbols

Magnesium Magnesium
alloy Casting alloy

Magnesium
alloy diecasting

Zinc alloy Zinc alloy emaining

diecasting
emaining

■Category and brevity code of thermoplastic resin

name symbol name symbol
ASB resin Polyethylene tephthalate
Acetal resin Polyethylene telephthalate
Methacrylic resin Polyimid
Acetyl cellulose Polyphenylene oxide
Tetrafluoride ethylene resin Polyphenylene sulfide
Trifluoride ethylene resin Polyalysulfone
Hexafluoride ethylene resin Polyarlylate
Fluoride vinyl resin Polypropylene
Fluoride vinyliden resin Polystyrene
Ethylene tetrafluoride ethylene copolymer Polysulfone
Ionomer Vinyl acetate resin
Methyl Benzene polyme Vinylidene chloride fiber
Nylon (Polyamide) AS resin
Polycarbonate Vinyl chloride resin
Polyethylene
・Thermoplastic resin : As temperature rises, this resin becomes soft → gammy → fluidity liquid. For example, polystyrene (PS) is like glass at normal temperature. From 60°C and
higher its elastic modules decreases, from 110°C it becomes gammy, and higher than 170°C, it becomes sticky paste.
Information
Technical

Technical-77

726
 31. Chemical Component table of work materials

Production data
Mechanical Property of Standard test block
Chemical Composition (%)
Tensile strength Heat treatment of
Hardness
others standard test block
remaining Casted

remaining Casted

remaining

remaining

remaining

■Kinds of thermosetting plastics and symbols

name symbol name symbol
Alkyd resin Phenol resin
Allyl resin Unsaturated polyester resin
Urea resin Silicone resin
Melamine resin Polyurethane
Epoxy resin
・Thermosetting resin : Heated at 80 °C, it becomes sticky paste with fluidity. Then it is injected into the mould under pressure. Once hardened, the plastics does not get soft owing
to polymer processing.

Information
Technical

Technical-78

727
 32. Materials used for Cutting Tools

■Materials
Description of products

We have been seeking the best materials used for cutting tools since the company establishment because the performance of tools are depending
on the selection of materials used. Major materials used in our company are listed below.

(1) Taps HSS : Equivalent to SKH58, SKH51, SKH56

Powder HSS (SKH10, High Vanadium High cobalt material)

Carbide : Cemented Carbide Materials of ultra micro grain

(2) Dies HSS : SKH51, SKH56

Alloy Tool Steel : SKS2, SKS21, SKS3, SKS31

(3) Center Drills and Centering Tools HSS : SKH51, SKH56

Powder HSS (SKH10, High Vanadium High cobalt material)

Carbide :  Cemented Carbide Materials of ultra micro grain

※For product's improvement, material may be changed without notice.

■Circumstance of tools' materials

Tensile strength, heat resistance, corrosion resistance and accuracy are the important features required of tool’ s materials. These requirements
have been changing due to miniaturization and lightening of parts.
And manufacturing methods, as well, have been changing because of necessity of economical efficiency such as saving process/cycle time while
parts become hard-to-machine type and their hardness increases.
As a result, the demand of industrial tools by users has become very tough.
For example, higher wear resistance and chipping resistance are required in the area of hardness, and heavy cutting process or high-speed cutting
are required in the area of cycle time.
Moreover, product accuracy with its rigidity, laborsaving brought by uniformity, and systematic reliability are highly required.
Therefore, technological improvement of tool steels never stops developing so that they satisfy users needs.
○The major materials used for taps are already listed in the chart, but those materials are ready to develop from conventional alloy tool steels and
current high speed steel into next generation materials such as cemented carbide and cermet materials.
New materials are developed even in high-speed tool steel area, such as SKH51 and SKH58 from SKH2, and they are moving into high performance
materials, such as high vanadium, cobalt, and powder HSS made of high vanadium and high cobalt contents.
○As the material for round dies, were alloy tool steels mostly used because of the relationship with the use of adjustable round dies. However, for
the hard-to-machine material. die material has been shifted into High Speed Steel.
○Major materials for center drills and centering tools are high speed steel materials, but they have been shifting to cobalt type or even cemented
carbide from SKH51.
We keep on seeking to develop our technology to meet user's needs and are trying to find the best materials in collaboration with steel
manufacturers.
Information
Technical

Technical-79

728
 32. Materials used for Cutting Tools

■Chemical composition of the materials specified in JIS

Description of products
Chemical composition
Classification Symbols

W type HSS ≦0.45 17.20 18.70

≦0.45

≦0.45

≦0.45

Mo type HSS 0.88 ≦0.45 4.70 5.20 5.90 1.70 2.10

≦0.45 5.50 6.50 5.90

1.15 ≦0.45 4.70 5.20 5.90 2.70 3.20

≦0.45 4.20 5.00 5.20 6.00 3.70 4.20

0.87 ≦0.45 4.70 5.20 5.90 2.10 5.00

≦0.45 4.70 5.20 5.90 2.10

≦0.45 3.20 3.90 10.00 3.50 9.50 10.50

≦0.7

1.05 ≦0.7 1.30

Cross chart
Classification Symbols Usage

W type HSS Tools for general cutting and other kinds of tools.

Tools for high speed heavy cutting and other kinds of tools.

Tools for cutting hard -to-machine materials and other kinds of tools.

Tools for cutting ultra hard-to-machine materials and other kinds of tools.

Mo type HSS General cutting tools from which toughness is particularly

required, and other kinds of tools.

Tools for cutting high hardness material from which

comparatively high toughness is required and other kinds of tools.

Tools for cutting ultra hard-to-machine materials and other kinds of tools.

High speed cutting tools from which comparatively high

toughness is required and other kinds of tools.

Tools for cutting ultra hard-to-machine materials and other kinds of tools.
General cutting tools from which toughness is particularly
required, and other kinds of tools.

High speed heavy cutting tools from which comparatively

high toughness is required, and other kinds of tools.

The standard of HSS material is specified in JIS. But there are many HSS materials which standard is not specified in JIS. Recently even the kind of
HSS-P is getting wider and various. Besides, SKH10, SKH53, SKH57 and their equivalents, such Hi vanadium/hi cobalt material as contains 4-12%
vanadium and 8-11% cobalt is now being manufactured. Material engineering will be developed rapidly in the future. Under such situation, there
can be many cases where JIS symbols are not used, and the use of larger classification and their symbols is getting popular.
Information
Technical

Technical-80

729
 33. Design of taps and dies

＊Design of oil hole : refer to icons shown in product page

Product design

e-1
Information
Technical

No square : for M4 and smaller,

Internal center on tap end : M8 and larger
Technical-81

730
 33. Design of taps and dies

Product design
Major Dia.

Major Dia.

Major Dia.

Simbols common in cutting tools

and tool dimensions

Symbols were used by each tool manufacturer by refering to his own

specification, resulting in confusion. In order to increas convenience at
customers, small tool association and carbide tool association in Japan
confirmed the common symbols. Yamawa is adopting these common
symbols in this cataloge.
Information
Technical

Overall Thead Chamfer Thread+Neck Outside Shank Length of Size of

length length length length dia. dia. square square

Technical-82

731
 34. Design of center drills and centering tools
Product design

c and smaller

Dc

c and larger

Dc 1.0 and larger

Ce-1

c and smaller

c and larger
Information
Technical

Technical-83

732
35. Design of dies

Dd

Product design
Db De

Dc Df

36. Design of taps for USA market and European market

Design of taps for USA market

Ub

Information
Technical

Technical-84

733
 36. Design of taps for USA market and European market

Design of taps for European market

DIN371 DIN5157/DIN2181
Product design

SU2-SP 5P 2P
F
M
V
V F

DIN374/376 ISO529

DIN351/352 Ea

5P 3.5P 2P
F
M
V
V M F

Eb

DIN357

DIN5156 Ec
Information
Technical

Technical-85

734