International Institute of GD&T

IIGDT

GD&T – Measurement Implications

Presented to “PC-DMIS User Group”
In Affiliation with Productivity Quality Inc.
April 13, 2004

Dr. Greg Hetland, President – IIGDT

e-mail: greg-hetland@iigdt.com 1
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
Website: www.iigdt.com
 Dimensioning & Tolerancing Standards

ANSI Y14.5M - 1982 ASME Y14.5M - 1994 ASME Y14.5.1M - 1994

2
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Technology Challenges & Constraints
• Miniaturization & Tolerance Truncation
• Cycle-time Competing with Precision Requirements

Business Challenges & Constraints

• Decreasing Profit Margins
• Tolerances Decreasing - Bad Decisions Increasing

High-Risk Issue
• Inability to represent functional intent through
engineering drawings and specifications.

3
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Size per “Rule #1” (two parts)
Controls the limits of size and the boundary of perfect form at it’s
Maximum Material Condition (MMC).
This on the Drawing Means This

; 20>1 ; 20>1 (MMC) ; 20>1 (MMC)

20>0
MMC perfect
form boundary
; 20 (LMC)

; 20 (LMC) ; 20 (LMC)

Issue: Verifying Problem: Statistical

“actual local size” analysis of size in
using two opposed most cases is
points per limited to only one
ASME Y14.5M-1982 parameter and in
-vs- many cases it is
a sphere per neither one of the
ASME Y14.5M-1994 defined parameters.
4
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Size - Rule #1 cont.
Rule #1 does not control the interrelationship between features.

“Perceived”
inner and outer 25.1 25 ± 0.124.9
boundaries

49.9
50 ± 0.1
Non-Ideal Part
50.1
will not fit inner &
Ideal Part
outer boundary and
“is not” rejectable.

5
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Incomplete Utilization of GD&T Tools

[â|).)%|A]
[à|).)%|A] [à|).)%|A]

25 ± 0.1

A
50 ± 0.1
[Å|).)%]

Problems with intersecting edges and planes

6
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Problems in +/- Tolerancing

Min R 1.8

Zero tolerance

R 2 = 0.2 Max R 2.2

Zero tolerance

This tolerance… …yields this boundary

Zero Tolerance Condition
7
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Problems in +/- Tolerancing cont.

0.443 (.01745) 0.443 (.01745)

Width Effect on Angle & Length

0.443 mm / 1º / 25 mm
25 mm
90 º ± 1º (.01745 in / 1º / 1 in)

8
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 “ASME Y14.5’s” Position on +/- Tolerancing

Except for true features of size (full circle, full

cylinder, full sphere, and fully opposed parallel
planes), +/- tolerancing will be extracted from the
text and examples of future releases of ASME Y14.5

This decision was made by the ASME Y14.5

Committee after a thorough review of +/- tolerancing
techniques in comparison to GD&T techniques for
clarity and accuracy of engineering drawings and
documentation.

9
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Precision GD&T – Uniform Boundary

[Ö|).!]
0.1

25

50

“Profile Tolerancing Controls Simple and Complex Geometries”

10
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Composite Profile Tolerancing - [A] …

“Controls Location”
“Controls size and shape”

[).*|A|B|C] [).@|A]

0.2
0.8

Lower constraint
to datum A
allows translation
& rotation

11
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Profile Calculation Errors
• Errors can occur in some situations
• Example: deviation of point shown can be calculated in
several locations
• Accept/reject is straightforward, but calculating deviations
causes problems

Nominal
Actual

Tolerance
Bands
12
© IIGDT -• 2003
April 13-2004 • Presentation to PC-DMIS User Group
 Actual Mating Envelope
“Actual mating envelope” is defined according to the type of feature as
follows:
(A) For an Internal Feature. A similar perfect feature counterpart of
largest size that can be inscribed within the feature so that it just contacts
the surface at the highest points.
External Feature: Circumscribed

Largest Inscribed
Feature

Actual Feature

See CAUTION Next Page

13
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Size & Location Effects Due to CMM Fitting

SMALLEST CIRCUMSCRIBED DIAMETER (OD)

LEAST SQUARES (Avg.) FIT
LARGEST INSCRIBED DIAMETER (ID)

ACTUAL SURFACE
Axial Shift

DETAIL

CAUTION: For applications where Least Squares best reflects the design
intent, it must be identified by a drawing note.
14
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Tertiary Datum Feature (RFS)
When a FOS is referenced as the tertiary datum RFS the AME must be
constrained to the primary and secondary datums. The following figure
describes how the center axis of the feature of size defined as the tertiary
datum RFS is established.
0 [@X:!$] [@*] 6 0
;3=0>12 0
[à|?).)@%|A] [A]

[B] [!@.&]

Tertiary Datum
Feature “C” (RFS)
[#*.!]
[$$.%]

;4>8=0>12 [Ö|).%|A|B:|C]
[ä|?).)@%é|A|B]

[C] Datum C = Axis of AME (Axis of Largest

Inscribed Cylinder Perpendicular to Datum 15
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group A and Located (BASIC) to the Datum B.
 Implications of Incorrect Datum
Alignment at RFS
Datum Feature B

Datum B (Axis of AME)

Datum Feature C

Datum C (Axis of AME)

Least Squares ;

Axis of
Least Squares ;
Angular Error
Note: Magnitude of individual and related
effects caused by this Angular Error must
16
be determined on a case-by-case basis.
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Primary Datum Feature (RFS)
LMC ;12.63 A
MMC ;12.37 ;12>5 +/- 0>13

“Obround” Shaped Condition “Coned” Shaped Condition

17
© IIGDT -• 2003
April 13-2004 • Presentation to PC-DMIS User Group
 Datum Reference Frame

18
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Datum Implications

[ä|?).#%:é|:: A: |: B: :|: C: ]

B C A B

All measurements are to be taken from the

mutually perpendicular planes.
Any measurements not taken from these
planes will induce measurement error/bias. 19
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Implications of Incorrect “CMM”
Applications on Inclined Datum Features

Angle greater than 45°

Angle less than 45°

150

Caution – Angular (Inclined) datum

features may result in unacceptable shift
20
if CMM points are projected to datum B.
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Composite Position Example with
Multiple Holes Defined as a Single Datum

64 +/- 1
2X 58
3

2X 36 6
5
[B]
2
2X 6
0
0
[C] 2X ;3 + 0.2
4X ;7 + 0.4

21
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 Position Cont.
During inspection the part was located relative to the A, B, C datum
reference frame. All measurements in the following table are from this
setup. The “X” and “Y” values represent the displacement from true
position.
Hole Hole Hole “X” “Y” Pattern Pattern Tol ; to ; ; to ;
# MMC Actual Dim Dim Tol Actual Tol Tol
Size Allowed
[ä|?).%:é|A|B|C] [ä|?).!:éActual
Allowed |A]
1 6.6 6.9 -0.1 -0.2 0.8 0.45 0.4 0.45
-----------

2 6.6 6.8 +0.2 -0.2 0.7 0.57 0.3 0.57

-----------

3 6.6 6.9 -0.1 -0.1 0.8 0.28 0.4 0.28

-----------

4 6.6 6.8 +0.2 -0.1 0.7 0.45 0.3 0.45

-----------

[ä|?).!:é|A|Dé]
5 2.8 3.0 0.0 -0.15 0.3 0.3
-----------

6 2.8 2.9 0.0 -0.1 0.2 0.2

-----------
Incorrect Answers
Notice that all of the holes are within their pattern tolerance value (upper
segment) but they failed their hole to hole tolerance (lower segment). Because
the displacement values are relative to the datum reference frame, they may not
represent the actual hole to hole values. 22
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 2D Paper Gaging
Hole “X” “Y”
# Dim Dim - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4

1 -0.1 -0.2
2 +0.2 -0.2
Hole #6
3 -0.1 -0.1
X = 0.0
4 +0.2 -0.1 0.4
y = -0.1
0.3
Hole #3 Hole #4
5 0.0 -0.15 0.2 X = -0.1 X = 0.2
6 0.0 -0.1 0.1 y = -0.1 y = -0.1

0 0
- 0.1

- 0.2 Hole #1 Hole #2

X = -0.1 X = 0.2
- 0.3
y = -0.2 y = -0.2
- 0.4 Hole #5
X = 0.0
y = -0.15

23
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 2D Paper Gaging
Caution, 2D paper gaging does not pick up rotational error
Hole “X” “Y”
# Dim Dim - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4

1 -0.1 -0.2
2 +0.2 -0.2
Hole #6 1.5
3 -0.1 -0.1 1.4

X = 0.0 1.2
1.3

4 +0.2 -0.1 0.4

1.1
y = -0.1 0.9
1

0.3
Hole #3 0.8 Hole #4
0.7

5 0.0 -0.15 0.2 X = -0.1 0.5

0.6
X = 0.2
0.4

6 0.0 -0.1 0.1 y = -0.1 0.2

0.3
y = -0.1
0.1
0 0
- 0.1

Hole Pattern Pattern ; to ; ; to ; Hole #1 Hole #2

- 0.2
# Allowed Actual Allowed Actual
X = -0.1 X = 0.2
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A] - 0.3
y = -0.2 y = -0.2
1 0.8 0.45 0.4 --------
0.45 - 0.4 Hole #5
2 0.7 0.57 0.3 0.57
-------- X = 0.0
3 0.8 0.28 0.4 0.28
-------- y = -0.15
4 0.7 0.45 0.3 0.45
--------
[ä| ?).!:é | A| Dé]
0
5 0.3 -------
0.3
6 0.2 0.2
------ 24
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 2D Paper Gaging
Caution, 2D paper gaging does not pick up rotational error
Hole “X” “Y”
# Dim Dim - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4

1 -0.1 -0.2
2 +0.2 -0.2
Hole #6
3 -0.1 -0.1
X = 0.0
4 +0.2 -0.1 0.4
1.5
y = -0.1 1.4
0.3 1.3
Hole #3 Hole #4
1.2
1.1
5 0.0 -0.15 0.2 X = -0.1 0.9
1
X = 0.2
0.8
6 0.0 -0.1 0.1 y = -0.1 0.7 y = -0.1
0.6
0.5
0 0.4 0
0.3
0.2
- 0.1 0.1

Hole Pattern Pattern ; to ; ; to ; Hole #1 Hole #2

- 0.2
# Allowed Actual Allowed Actual
X = -0.1 X = 0.2
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A] - 0.3
y = -0.2 y = -0.2
1 0.8 0.45 0.4 --------
0.45 0.33- 0.4 Hole #5
2 0.7 0.57 0.3 0.57 0.32
-------- X = 0.0
3 0.8 0.28 0.4 0.28 0.32
-------- y = -0.15
4 0.7 0.45 0.3 0.45 0.31
--------
[ä| ?).!:é | A| Dé]
0
5 0.3 -------
0.3 Rough optimization
6 0.2 0.2
------ 25
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 2D Paper Gaging
Caution, 2D paper gaging does not pick up rotational error
Hole “X” “Y”
# Dim Dim - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4

1 -0.1 -0.2
2 +0.2 -0.2
Hole #6
3 -0.1 -0.1
X = 0.0
4 +0.2 -0.1 0.4
1.5
y = -0.1 1.4
0.3 1.3
Hole #3 Hole
1.2 #4
1.1
5 0.0 -0.15 0.2 X = -0.1 0.9
1
X = 0.2
0.8
6 0.0 -0.1 0.1 y = -0.1 0.7 y = -0.1
0.6
0.5
0 0.4 0
0.3
0.2
- 0.1 0.1

Hole Pattern Pattern ; to ; ; to ; Hole #1 Hole #2

- 0.2
# Allowed Actual Allowed Actual
X = -0.1 X = 0.2
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A] - 0.3
y = -0.2 y = -0.2
1 0.8 0.45 0.4 --------
0.45 0.37- 0.4 Hole #5
2 0.7 0.57 0.3 0.57 0.27
-------- X = 0.0
3 0.8 0.28 0.4 0.28 0.37
-------- y = -0.15
4 0.7 0.45 0.3 0.45 0.27
--------
[ä| ?).!:é | A| Dé]
0
5 0.3 -------
0.3 When pattern is optimized
6 0.2 0.2
------ 26
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 2D Paper Gaging
Caution, 2D paper gaging does not pick up rotational error
Hole “X” “Y”
# Dim Dim - 0.4 - 0.3 - 0.2 - 0.1 0 0.1 0.2 0.3 0.4

1 -0.1 -0.2
2 +0.2 -0.2
Hole #6
3 -0.1 -0.1
X = 0.0
4 +0.2 -0.1 0.4
1.5
y = -0.1 1.4
0.3 1.3
Hole #3 Hole #4
1.2
1.1
5 0.0 -0.15 0.2 X = -0.1 0.9
1
X = 0.2
0.8
6 0.0 -0.1 0.1 y = -0.1 0.7 y = -0.1
0.6
0.5
0 0.4 0
0.3
0.2
- 0.1 0.1

Hole Pattern Pattern ; to ; ; to ; Hole #1 Hole #2

- 0.2
# Allowed Actual Allowed Actual
X = -0.1 X = 0.2
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A] - 0.3
y = -0.2 y = -0.2
1 0.8 0.45 0.4 --------
0.45 - 0.4 Hole #5
2 0.7 0.57 0.3 0.57
-------- X = 0.0
3 0.8 0.28 0.4 0.28
-------- y = -0.15
4 0.7 0.45 0.3 0.45
--------
[ä| ?).!:é | A| Dé]
0
5 0.3 -------
0.3 0.13
6 0.2 0.2 0.16
------ 27
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group When datum shift is taken into consideration
 3D Paper Gaging
- 0.4 - 0.2 0.2 0.4 - 0.4 - 0.2 0.2 0.4
- 0.3 - 0.1 0 0.1 0.3 - 0.3 - 0.1 0 0.1 0.3

0.4
Hol “X” “Y” 0.4
0.3 Hole #1 Hole #3 0.3
e# Dim Dim 0.2 0.2

0.1 0.1
1 -0.1 -0.2 0 0
- 0.1 - 0.1
2 +0.2 -0.2 - 0.2 - 0.2

- 0.3 - 0.3
3 -0.1 -0.1 - 0.4 - 0.4
0 0
4 +0.2 -0.1 0.2 0.2

0.1 0.1

0 0
5 0.0 -0.15 - 0.1 - 0.1
- 0.2 - 0.2

6 0.0 -0.1
Hole #5 Hole #6

3D paper gaging provides the

ability to analyze both the
translational and rotational effects 0.4
0.3 Hole #2 Hole #4
0.4
0.3

of the pattern of holes to itself and 0.2 0.2

0.1 0.1
also the composite effects of one 0 0
or more patterns in relationship to - 0.1
- 0.2
- 0.1
- 0.2

a multiple hole pattern defined as - 0.3 - 0.3

- 0.4
- 0.4
a single datum. - 0.3 - 0.1 0.1 0.3 - 0.3 - 0.1 0.1 0.3
28
- 0.4 - 0.2 0 0.2 0.4 - 0.4 - 0.2 0 0.2 0.4

© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group

 3D Paper Gaging - 0.4 - 0.2 0.2 0.4 - 0.4 - 0.2 0.2 0.4
- 0.3 - 0.1 0 0.1 0.3 - 0.3 - 0.1 0 0.1 0.3

0.4
Hol “X” “Y” 0.4
0.3 Hole #1 0.8 Hole #3 0.8 0.3
e# Dim Dim 0.2 0.5
0.6
0.7

0.5
0.6
0.7
0.2
.04 .04

0.1 .02
.03
.02
.03
0.1
1 -0.1 -0.2 0
.01 .01
0
- 0.1 - 0.1
2 +0.2 -0.2 - 0.2 - 0.2

- 0.3 - 0.3
3 -0.1 -0.1 - 0.4 - 0.4
0 0
4 +0.2 -0.1 0.2 0.2
.04 .04

0.1 .02
.03
.02
.03 0.1
.01 .01
0 0
5 0.0 -0.15 - 0.1 - 0.1
- 0.2 - 0.2

6 0.0 -0.1
Hole #5 Hole #6

Hole Pattern Pattern ; to ; ; to ;

# Allowed Actual Allowed Actual
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A]
0.4 0.4
1 0.8 0.45 0.4 --------
0.45 Hole #4
0.3 Hole #2 0.7
0.8
0.7
0.8 0.3

2 0.7 0.57 0.3 0.57

-------- 0.2
.04
0.5
0.6

.04
0.5
0.6 0.2

0.1 .03 .03 0.1

3 0.8 0.28 0.4 0.28
-------- .01
.02
.01
.02

0 0
- 0.1
4 0.7 0.45 0.3 0.45
-------- - 0.1
- 0.2 - 0.2
[ä| ?).!:é | A| Dé] - 0.3 - 0.3

5 0.3 -------
0.3 - 0.4 - 0.4
- 0.3 - 0.1 0.1 0.3 - 0.3 - 0.1 0.1 0.3
6 0.2 0.2
------ - 0.4 - 0.2 0 0.2 0.4 - 0.4 - 0.2 0 0.2 0.4 29
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 3D Paper Gaging - 0.4 - 0.2 0.2 0.4 - 0.4 - 0.2 0.2 0.4
- 0.3 - 0.1 0 0.1 0.3 - 0.3 - 0.1 0 0.1 0.3

0.4
Hol “X” “Y” 0.4
0.3 Hole #1 Hole #3 0.3
e# Dim Dim 0.2
0.8
0.7 0.2
0.6

0.1 0.8
.04
0.5
0.1
1 -0.1 -0.2
0.7

0 0
0.6 .03
0.5 .02
.04 .01

- 0.1 .03 - 0.1

2 +0.2 -0.2 - 0.2 .01
.02
- 0.2

- 0.3 - 0.3
3 -0.1 -0.1 - 0.4 - 0.4
0 0
4 +0.2 -0.1 0.2 0.2

0.1 0.1
.04

0 .04
.03
.02
0
5 0.0 -0.15 - 0.1
.01
.03
.02
.01
- 0.1
- 0.2 - 0.2

6 0.0 -0.1
Hole #5 Hole #6

Hole Pattern Pattern ; to ; ; to ;

# Allowed Actual Allowed Actual
[ä| ?).%:é| A| B| C] [ä| ?).!:é | A]
0.4 0.4
1 0.8 0.45 0.4 --------
0.45 Hole #4
0.3 Hole #2 0.8
0.3

2 0.7 0.57 0.3 0.57

-------- 0.2
0.6
0.7 0.2
0.5
0.1 0.8
.04 0.1
3 0.8 0.28 0.4 0.28
-------- 0.6
0.7
.03

0 .04
0.5
.01
.02
0
- 0.1
4 0.7 0.45 0.3 0.45 - 0.1 .03
-------- .02

- 0.2
.01
- 0.2
[ä| ?).!:é | A| Dé] - 0.3 - 0.3

5 0.3 -------
0.3 - 0.4 - 0.4

6 0.2 0.2
------
All Results <0.1 - 0.3
- 0.4
- 0.1
- 0.2 0
0.1
0.2
0.3
0.4
- 0.3 - 0.1
- 0.4 - 0.2 0
0.1
0.2
0.3
0.4 30
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 GD&T - A Core Foundational Element to:
• DFM, Six-Sigma, ISO 9000 & Reliability
– Critical assumptions by “all”
Functional / design intent must clearly be understood

D&T must clearly define magnitude of allowable

variation required to achieve functional intent.

Every feature must have the greatest amount of

tolerance allowed to fully achieve functional intent.

All requirements must be clearly

understood by all applicable individuals

31
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 IIGDT Public Courses
Basic Blueprint Reading (1-day)
Objective: To understand basic components, sections, views, terminology and
graphical representation of an engineering drawing.

GD&T- Introduction & Fundamental Principles (2-day)

Objective: To provide fundamental lessons in proper interpretation of
engineering drawings used in the design, manufacture and inspection of parts
which have geometric controls applied per ANSI Y14.5M-1982
and ASME Y14.5M-1994.

GD&T- Advanced Applications & Analysis (2-day)

Objective: To provide advanced information in "applications and analysis“
(per ASME Y14.5M-1994 and ASME Y14.5.1M-1994) involving optimization
strategies for given design applications, manufacturing methodologies and
measurement implications.
Seminars scheduled for week of May 17, 2004 at the University of Minnesota
See “www.iigdt.com” for details 32
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group
 g{tÇ~ çÉâ
For pdf copy of presentation,
give me your business card or
e-mail me at
greg-hetland@iigdt.com

For Charts or Training, visit

www.iigdt.com

33
© IIGDT • April 13-2004 • Presentation to PC-DMIS User Group