Metallurgy of
Gear Cutting Tools
Presented by
Kurt Switzer
Gleason Cutting Tools Corporation
1 Gear School / Cutting Tool Metallurgy
2 Gear School / Cutting Tool Metallurgy
Topics of Discussion
High Speed Steels and Heat Treatment
Intermetallic Exotics
Cemented Carbides
Coatings and Tool Reconditioning
3 Gear School / Cutting Tool Metallurgy
Desired Tool Characteristics
High Hardness
High Red Hardness
High Abrasion (Wear) Resistance
High Toughness
4 Gear School / Cutting Tool Metallurgy
High Speed Steels
Conventional
vs.
Particle Metallurgy
5 Gear School / Cutting Tool Metallurgy
High Speed Steels
Conventional
Ingot
Casting
6 Gear School / Cutting Tool Metallurgy
High Speed Steels
Carbides
Metal Matrix
Metal Matrix
7 Gear School / Cutting Tool Metallurgy
High Speed Steels
Conventional HSS Material
Metal Matrix
Carbides
8 Gear School / Cutting Tool Metallurgy
High Speed Steels
Particle Metallurgy
Bohler Video
14 Gear School / Cutting Tool Metallurgy
High Speed Steels
Conventional vs. Particle
15 Gear School / Cutting Tool Metallurgy
High Speed Steels
G20 / G40 Material Toughness
22
Toughness Charpy “C” Notch (ft lbs)
20
18
16
14 G20
12
10
8
6
G20 G40
4
2
G40 G50
0
Conventional Particle Metallurgy
16 Gear School / Cutting Tool Metallurgy
High Speed Steels
GCTC Industry Equivalents
Grade
G10 M35 conventional
G20 CPM M4, ASP2004, S690, AISI M4
G30 CPM REX45, ASP2030, S592
G40 CPM T15, ASP2015, AISI T15
G50 CPM REX76, ASP2048, S376, AISI M48
G60 CPM REX86, ASP2060, S290
G70 CPM REX66, ASP2052, S392
17 Gear School / Cutting Tool Metallurgy
High Speed Steels
18 Gear School / Cutting Tool Metallurgy
High Speed Steels
Basic components of Steel:
Iron (Fe), Carbon (C)
Carbide Forming Additions:
Chromium (Cr), Molybdenum (Mo), Tungsten (W), Vanadium (V)
Red Hardness Addition:
Cobalt (Co) – Added for Red-Hardness
Other Additions:
Silicon (Si), Manganese (Mn) Sulphur (S)
19 Gear School / Cutting Tool Metallurgy
High Speed Steels
C Cr W Mo V Co Tot
G10 1.2 4.1 6.0 5.0 3.0 5.0 24.3
(conventional)
G20 1.4 4.3 5.8 4.5 3.6 --- 19.6
G30 1.3 4.1 6.3 5.0 3.1 8.3 28.1
G40 1.6 4.0 12.3 --- 5.0 5.0 27.9
G50 1.5 3.8 10.0 5.3 3.1 9.0 32.7
G60 2.0 4.0 10.0 5.0 5.0 9.0 35.0
20 Gear School / Cutting Tool Metallurgy
High Speed Steels
G20 vs. G60
21 Gear School / Cutting Tool Metallurgy
High Speed Steels
250
Red Hardness and Wear Resistance
200
Red Hardness Wear Resistance
150
100
50
0
M2 G10 G20 G30 G40 G50 G60
22 Gear School / Cutting Tool Metallurgy
Intermetallic Alloys
23 Gear School / Cutting Tool Metallurgy
GCTC Industry Equivalents
Grade
G90 MC90
24 Gear School / Cutting Tool Metallurgy
High Speed Steels
C Cr W Mo V Co Tot
G20 1.4 4.3 5.8 4.5 3.6 --- 19.6
G30 1.3 4.1 6.3 5.0 3.1 8.3 28.1
G40 1.6 4.0 12.3 --- 5.0 5.0 27.9
G50 1.5 3.8 10.0 5.3 3.1 9.0 32.7
G10 1.2 4.1 6.0 5.0 3.0 5.0 24.3
(conventional)
G60 2.0 4.0 10.0 5.0 5.0 9.0 35.0
G90 0 0 0 15.0 0 25.0 40
25 Gear School / Cutting Tool Metallurgy
Composition of New Intermetallic Substrate
Chemical Composition (average mass %)
C Si Mn Cr Mo V W Co Fe
G90 0 0,6 0,2 0 15 0 0 25 Bal.
PM 1,3 0,6 0,3 4,2 5,0 3.0 6,3 8,4 Bal.
White phase, intermetallic phase White phase, primary carbides
(Fe,Co)7Mo6, (MC, M6C),
• tempered, C-free martensite
• tempered martensite
• secondary hardening by
• secondary hardening carbides
intermetallic phase
26 Gear School / Cutting Tool Metallurgy
G90
27 Gear School / Cutting Tool Metallurgy
High Speed Steels
Red Hardness and Wear Resistance
300
250
Red Hardness Wear Resistance
200
150
100
50
0
M2 G10 G20 G30 G40 G50 G60 G90
28 Gear School / Cutting Tool Metallurgy
Hardness of intermetallic cutting Materials
•G90
PM Material
G90 Material
29 Gear School / Cutting Tool Metallurgy
HSS Heat Treatment
30 Gear School / Cutting Tool Metallurgy
Heat Treatment
2500
Hardening
Temperature Degrees F
2000
1500
Tempering
1000
500
0 5 Time (hours) 10 15
31 Gear School / Cutting Tool Metallurgy
Heat Treatment
TTT Curve G30
32 Gear School / Cutting Tool Metallurgy
Heat Treatment
Bravais Lattices
Ferrite – Room Austenite -
Theoretical Temperature >1600° F
Unit Cell
Extended
Lattice
Simple Cubic Body-Centered Face-Centered
Cubic (BCC) Cubic (FCC)
33 Gear School / Cutting Tool Metallurgy
Heat Treatment
Bravais Lattices
Austenite - Martensite –
>1600° F Room Temp
Unit Cell
Extended
Lattice
Face-Centered Body Centered
Cubic (FCC) Tetragonal (BCT)
34 Gear School / Cutting Tool Metallurgy
Heat Treatment
35 Gear School / Cutting Tool Metallurgy
Heat Treatment
36 Gear School / Cutting Tool Metallurgy
Heat Treatment
Hardening
37 Gear School / Cutting Tool Metallurgy
Heat Treatment
38 Gear School / Cutting Tool Metallurgy
Heat Treatment
39 Gear School / Cutting Tool Metallurgy
Heat Treatment
40 Gear School / Cutting Tool Metallurgy
Heat Treatment
Tempering
41 Gear School / Cutting Tool Metallurgy
Heat Treatment
Tempering
42 Gear School / Cutting Tool Metallurgy
Cemented Carbides
43 Gear School / Cutting Tool Metallurgy
Cemented Carbides
Tungsten carbide (WC) particles
“glued” together with cobalt metal.
Carbide Particle
Cobalt binder
44 Gear School / Cutting Tool Metallurgy
Cemented Carbides
45 Gear School / Cutting Tool Metallurgy
Cemented Carbides
Alloyed grades:
TiC - improves chemical wear resistance
lowers toughness
TaC and NbC - improves crater wear resistance
improves toughness
improves thermal shock resistance
46 Gear School / Cutting Tool Metallurgy
Cemented Carbides
Physical properties are affected by:
(Hardness, fracture toughness, wear resistance, etc.)
Percent Cobalt or other binder(s)
Volume fraction of various carbides
Size of various carbides
Size distribution of various carbides
47 Gear School / Cutting Tool Metallurgy
Cemented Carbides
Courtesy of Kennametal
48 Gear School / Cutting Tool Metallurgy
Cemented Carbides
GCT2 GCT4
Submicron Submicron
WC/Co grade WC/Co grade
General More wear
purpose grade resistant/less
tough than
GCT2
Should be recoated after
resharpening for best
performance
49 Gear School / Cutting Tool Metallurgy
Coatings
50 Gear School / Cutting Tool Metallurgy
Coatings
Tip Wear Corner Wear
Chipping
Cratering
Gouging
Flank Wear
51 Gear School / Cutting Tool Metallurgy
Coatings
52 Gear School / Cutting Tool Metallurgy
Coatings
Physical Vapor Deposition Coatings (“PVD”)
Low Temperature (<500° C)
Thin Film (<6 microns or 0.00025”)
Maintain sharp cutting edges
High internal compressive stresses
Line of Sight process
53 Gear School / Cutting Tool Metallurgy
Coatings
0.001”
Human Hair
0.0001”
Micron
54 Gear School / Cutting Tool Metallurgy
Coatings
Titanium Nitride Titanium Aluminum Nitride
55 Gear School / Cutting Tool Metallurgy
Coatings
Surface Preparation Chemical Cleaning
56 Gear School / Cutting Tool Metallurgy
Coatings
Reactive Gas In Argon In
Targets
Workpiece table
To Vacuum Pump
57 Gear School / Cutting Tool Metallurgy
Coatings
Principles of Arc Evaporation
2 A vapor bubble is
1 Arc formed at the cathode
spot
melted material
Target = cathode
The vapor bubble Droplets are formed
3 4 and fly off at an angle <
explodes and the
ionized material 45°
evaporates
Path of droplets
Droplets
Coating
58 Gear School dataTool
/ Cutting courtesy of Oerlikon
Metallurgy Balzers
Coatings
TiAlN at 25,000x magnification
2μ
Coating
59 Gear School dataTool
/ Cutting courtesy of Oerlikon
Metallurgy Balzers
Coatings
AlCrN at 25,000x magnification
2μ
Coating
60 Gear School dataTool
/ Cutting courtesy of Oerlikon
Metallurgy Balzers
Coatings
61 Gear School / Cutting Tool Metallurgy
Coatings
Arc
Video
63 Gear School / Cutting Tool Metallurgy
Coatings
Detail of Plasma Action
Ti+
Negative
N+
Plasma
64 Gear School / Cutting Tool Metallurgy
Coatings
65 Gear School / Cutting Tool Metallurgy
Coatings
66 Gear School / Cutting Tool Metallurgy
Coatings
Balzers BAI-1200 Hauzer HTC-1000
67 Gear School / Cutting Tool Metallurgy
Coatings
68 Gear School / Cutting Tool Metallurgy
Coatings
Coating Quality
Thickness Hardness
Adhesion
69 Gear School / Cutting Tool Metallurgy
Coatings
TiNite® Coating Properties
Coating Material TiN
Microhardness (HV 0.05) 2,300
Friction coefficient against steel (dry) 0.4
Max. service temperature (°C) 600
Coating color gold-yellow
TiNite® is where it all started and remains a proven and versatile standard coating .
Recommended applications:
steel cutting
punching and forming (when working low-hardness materials)
moulds for the injection moulding of plastics
plungers of diesel injection pumps
medical instruments
70 Gear School / Cutting Tool Metallurgy
Coatings
AlNite®
Coating Properties
Coating Material TiAlN
Microhardness (HV 0.05) 3,300
Friction coefficient against steel (dry) 0.30 - 0.35
Max. service temperature (°C) 900
Coating color violet-grey
AlNite® is an optimized relationship of hardness and residual compressive stress that increases
the stability of the cutting edges of machining tools.
Recommended applications:
HSS and carbide tools exposed to high thermal stresses (drilling, turning, dry machining, HSC)
plastic injection moulding (moulds with textured surfaces, processing of melts with fiberglass reinforcement)
combustion engine components
71 Gear School / Cutting Tool Metallurgy
Coatings
72 Gear School / Cutting Tool Metallurgy
Coatings
AlCroNite® Pro Coating Properties
Coating Material AlCrN
Microhardness (HV 0.05) 3,200
Friction coefficient against steel (dry) 0.35
Max. service temperature (°C) 1,100
Bluish
Coating color
grey
AlCroNite® Pro is a new top-tier all-rounder in cutting applications, in punching and forming as well as
in aluminum pressure die casting. Excellent wear resistance, thermal shock stability and hot hardness
are the properties that are modified to enhance the proven AlCroNite® coating.
Recommended applications:
Solid carbide end mills and carbide indexable inserts for roughing and finishing
Carbide and HSS hobs (Wet/Dry Machining)
Forming and punching tools
Aluminum die casting
73 Gear School / Cutting Tool Metallurgy
Coatings
AlCroNite® Gear Pro Coating Properties
Coating Material AlCrN +
Microhardness (HV 0.05) 3,800
Friction coefficient against steel (dry) 0.30
Max. service temperature (°C) >1,100
Coating color Light grey
AlCroNite® Gear Pro is optimized for the most extreme gear cutting conditions. Applicable to hobs,
shaper cutters and bevel cutting tools, it allows feeds and speeds to be increased well beyond those used
with previous generation AlCroNite® coatings. Gear Pro has the highest hot hardness, wear resistance
and oxidation resistance along with lowest thermal conductivity of the Gleason coating portfolio.
Recommended applications:
Cylindrical and Bevel Gear cutting
74 Gear School / Cutting Tool Metallurgy
Coatings
75 Gear School / Cutting Tool Metallurgy
Coatings
76 Gear School / Cutting Tool Metallurgy
Coatings
10000
9000
8000
Vickers Hardness
7000
6000
5000
4000
3000
2000
1000
0
HSS Hard Carbide PVD cBN Diamond
Chrome Coatings
77 Gear School / Cutting Tool Metallurgy
Coatings
78 Gear School / Cutting Tool Metallurgy
Reconditioning
79 Gear School / Cutting Tool Metallurgy
Reconditioning
Stripping Sharpen Coat
80 Gear School / Cutting Tool Metallurgy
Reconditioning
Stripping HSS and Carbide
Coating Recommended
stripping cycle
TiNite® Can be re-coated
multiple times
AlNite® Strip every time
AlCroNite®
Pro Strip every time
Chemical process that oxidizes the metal in coating.
81 Gear School / Cutting Tool Metallurgy
Reconditioning
Stripping
82 Gear School / Cutting Tool Metallurgy
Reconditioning
Sharpening Incomplete wear removal
83 Gear School / Cutting Tool Metallurgy
Reconditioning
Sharpening burn
84 Gear School / Cutting Tool Metallurgy
Reconditioning
Sharpening Cracks
85 Gear School / Cutting Tool Metallurgy
Reconditioning
Sharpening burn
86 Gear School / Cutting Tool Metallurgy
Reconditioning
Edge Preparation
87 Gear School / Cutting Tool Metallurgy
Reconditioning
Coating Adhesion
88 Gear School / Cutting Tool Metallurgy
Reconditioning
The Desired Result
89 Gear School / Cutting Tool Metallurgy
