Automotive Test & Measurement Case
Studies
SAAMF Roadshow Durban
CSIR NML
Eddie Tarnow
Metrologist: Torque & Automotive
14 June 2006
Case Study 1 – Seat safety testing
• A testing laboratory was required to perform a yield test on a
•
•
•
Slide 2
seat frame to be used in motor vehicles
The technical specification required that the seat yield at
an applied force of >20 kN, with a tolerance of ± 1 %.
The lab standard loadcell used had been calibrated by a
SANAS accredited calibration laboratory
Since inadequate contract review took place between the
testing lab and the calibration lab the calibration was not fit-forpurpose
© CSIR 2006
www.csir.co.za
Case Study 1 – Seat safety testing (2)
LOADCELL CALIBRATION CERTIFICATE
FORCE APPLIED
(kN)
UUT DISPLAYED
(kN)
10
10,5
20
20,1
30
30,2
40
40,0
50
50,2
60
60,1
70
70,3
80
80,0
90
90,1
100
100,3
Uncertainty of Measurement: ± (0,5 % of reading + 2 kN)
Slide 3
© CSIR 2006
www.csir.co.za
Case Study 1 – Seat safety testing (3)
• Test limits – 20 kN +/- 1 % = 19,8 kN to 20,2 kN
• Range due to uncertainty of measurement quoted on the
•
•
•
calibration certificate for the standard loadcell
20,1 kN +/- (0,5 % + 2 kN) = 17,9995 kN to 22,2005 kN
Clearly the uncertainty of measurement on the calibration of the
loadcell is larger than the test specification requirement
Conclusion:
• The loadcell, with its calibration CANNOT be used for the test.
Solution:
• To conduct a proper contract review with the calibration service provider
and insist on a smaller uncertainty. Alternatively purchase a better quality
loadcell if the loadcell itself contributed to the large calibration uncertainty.
Slide 4
© CSIR 2006
www.csir.co.za
Case Study 2 – Dimensional measurement
of a boot-lid-hinge
• A 1st tier supplier of boot-lid-hinges to the OEMs was required to
•
•
•
•
Slide 5
test their products for dimensional conformance to a technical
specification
They used a coordinate measuring machine to perform the
measurements
The dimensional technical specifications were indicated on a
drawing from the OEM
The component, as supplied, did not fit. This in spite of the
performance of conformance testing.
In an effort to solve the problem, a sample hinge was measured
at CSIR NML with the following results:-
© CSIR 2006
www.csir.co.za
Case Study 2 – Dimensional measurement
of a boot-lid-hinge (2)
M/MENT
I/D
Slide 6
NOMINAL
VALUE
(mm)
MEASURED
VALUE
(mm)
DEVIATION
(mm)
LOWER
LIMIT
(mm)
UPPER
LIMIT
(mm)
EXCEEDS
TOLERANCE
BY (mm)
DIM 1
283,4
282,769
-0,631
-0,5
0,5
0,131
DIM 3
23,8
21,969
-1,831
-0,5
0,5
1,331
DIM 5
8,5
7,780
-0,720
-0,5
0,5
0,220
DIM 6
81,4
89,035
7,635
-1,5
1,5
6,135
DIM 7
25,0
20,717
-4,283
-0,5
0,5
3,783
DIM 8
125,1
123,072
-2,028
-0,5
0,5
1,528
DIM 9
82,0
77,267
-4,733
-3,0
3,0
1,733
DIM 13
115,1
116,625
1,525
-0,5
0,5
1,025
DIM 16
16,5
18,065
1,565
-0,5
0,5
1,065
DIM 18
209,0
220,169
11,169
-1,5
1,5
9,669
DIM 19
63,3
60,172
-3,128
-0,5
0,5
2,628
DIM 20
228,5
229,214
0,714
-0,5
0,5
0,214
DIM 22
44,7
43,812
-0,888
-0,5
0,5
0,388
DIM LOC_Y2(Z)
506,46
502,246
-4,214
-0,5
0,5
3,714
DIM LOC_Z4(X)
3294,28
3291,280
-3,000
-0,5
0,5
2,500
DIM LOC_Z4(Y)
-550,49
-551,722
-1,232
-0,5
0,5
0,732
© CSIR 2006
www.csir.co.za
Case Study 2 – Dimensional measurement
of a boot-lid-hinge (3)
• On further investigation the following problems were discovered
relating to the CMM:• The calibration spheres being used for the compensation for probe error
•
were un-calibrated
The accuracy of CMM was unknown due to inadequate verification by an
external calibration service provider, even though it is used for conformance
testing
• Other general metrology related problems found were:•
•
Slide 7
The balance used for the twice daily checks on the dipping oil was uncalibrated and there was no check-weight for use as a confidence check
The hardness block being used as a standard was invalid as it had been
indented too many times and the indentations were too close to each other
© CSIR 2006
www.csir.co.za
Case Study 2 – Dimensional measurement
of a boot-lid-hinge (4)
• Conclusions:
•
•
the company has a serious lack of awareness about measurement and
testing requirements
The risk in this case is that of potentially losing the contract to supply these
components
• Solutions:
•
Slide 8
The SAAMF has consulted with them and a number of wide ranging
corrective actions have been identified.
© CSIR 2006
www.csir.co.za
Case Study 3 – Feedback on CMM audit
programme
• The CSIR NML initiated a CMM audit programme for the
purposes of:• Identifying and analysing national CMM capabilities.
• Assessing the validity of measurement traceability for CMM measurements.
• Assessing the influence of environmental conditions on CMM
measurements.
• The audit part was manufactured from aluminium to purposely
•
Slide 9
simulate the many aluminium components being measured on
CMMs
The audit part was manufactured to simulate a typical
automotive component to evaluate the capabilites of CMMs in
measuring related parameters
© CSIR 2006
www.csir.co.za
Case Study 3 – Feedback on CMM audit
programme (2)
Slide 10
© CSIR 2006
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Case Study 3 – CMM audit Results (3)
[PCD 66 mm]
PCD (Ø 66 m m ) (Ref 7.4.2)
65,960
65,950
65,940
Measured PCD (mm)
65,930
65,920
65,910
65,900
65,890
65,880
65,870
65,860
65,850
NML
Slide 11
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05 (1) LAB 05 (2) LAB 05 (3)
www.csir.co.za
LAB 06
NML
LAB 07 (1) LAB 07 (2) LAB 08 (1) LAB 08 (2)
NML
Case Study 3 – CMM audit Results (4)
[Bore Diameter 90 mm]
Bore dia. (Ø 90m m ) (Ref 7.4.3)
89,900
89,898
Measured Bore Diameter (mm)
89,890
89,884
89,885
89,884
89,881
89,880
89,876
89,880
89,877
89,876
89,876
89,88
89,879
89,876
89,874
89,873
89,870
89,868
89,860
89,858
89,850
NML
Slide 12
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (5)
[Distance 5 mm]
Distance (5 m m ) (Ref 7.4.7)
5,000
4,995
4,990
4,987
Distance Measured (mm)
4,985
4,980
4,975
4,975
4,975
4,973
4,974
4,977
4,976
4,975
4,974
4,973
4,971
4,970
4,974
4,972
4,972
4,973
4,965
4,961
4,960
4,955
4,950
NML
Slide 13
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (6)
[Distance 250 mm]
Distance (250 m m ) (Ref 7.4.8)
250,050
250,040
250,037
Distance Measured (mm)
250,041
250,040
250,039
250,036
250,033
250,032
250,031
250,030
250,031
250,031
250,030
250,027
250,024
250,020
250,020
250,010
250,000
NML
Slide 14
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (7)
[Outside Diameter 14 mm]
Outside dia.(Ø 14 m m ) (Ref 7.4.9)
14,060
14,050
Diameter Measured (mm)
14,044
14,045
14,043
14,041
14,040
14,039
14,038
14,035
14,036
14,035
14,030
14,037
14,036
14,034
14,029
14,028
14,020
14,010
NML
Slide 15
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (8)
[Outside Diameter 28 mm]
Outside dia.(Ø 28 m m ) (Ref 7.4.10)
28,100
28,080
28,078
28,071
Diameter Measured (mm)
28,060
28,056
28,047
28,040
28,040
28,039
28,043
28,043
28,048
28,047
28,040
28,039
28,042
28,043
28,040
28,031
28,020
28,001
28,000
27,980
27,960
27,940
NML
Slide 16
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (9)
[Concentricity]
Concentricity (Ref 7.4.11)
0,080
0,070
0,067
0,060
Concentricity Measured (mm)
0,057
0,050
0,040
0,030
0,021
0,020
0,010
0,008
0,008
0,009
0,009
0,000
NML
Slide 17
LB 01
LAB 02
NML
0
LAB 03
0,008
LAB 04
0,007
NML
© CSIR 2006
0,006
LAB 05
(1)
0,008
0,004
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
0,008
0,008
0,004
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (10)
[Roundness of Bore]
Roundness of Bore (Ref 7.4.4)
0,0335
0,033
0,031
0,03
Roundness Measured (mm)
0,0285
0,028
0,0235
0,020
0,020
0,0185
0,014
0,0135
0,013
0,012
0,010
0,010
0,010
0,009
0,0085
0,005
0,004
0,0035
NML
Slide 18
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (11)
[Included Angle]
Included Angle (Ref 7.4.6)
38,000
37,000
Angle Measured (degree)
37,000
36,926
36,936
36,956
36,936
36,933
36,920
36,927
36,966
36,943
36,925
36,894
37
36,903
36,967 36,954
36,000
35,000
34,000
33,760
33,000
32,000
NML
Slide 19
LB 01
LAB 02
NML
LAB 03
LAB 04
NML
© CSIR 2006
LAB 05
(1)
LAB 05
(2)
LAB 05
(3)
www.csir.co.za
LAB 06
NML
LAB 07
(1)
LAB 07
(2)
LAB 08
(1)
LAB 08
(2)
NML
Case Study 3 – CMM audit Results (12)
• Problems experienced:
•
•
•
•
•
•
Slide 20
Labs do not stick to timings or follow the protocol (audit instructions)
Very few labs can estimate uncertainty or even know the accuracy of their
CMM
Differences may be due to software packages used e.g. Roundness,
Concentricity (Form Measurements)
Audit sample not suitable for large CMMs
Lack of enthusiasm to participate (perhaps ignorance of value to be gained)
CMM agents reluctant to participate or distribute amongst their customers
© CSIR 2006
www.csir.co.za
Case Study 3 – CMM audit Results (13)
• Conclusions:
•
•
•
Slide 21
Length measurements and diameter measurements were in general
acceptable
Roundness, angle and concentricity measurements are cause for concern
Operator/metrologist competence maybe questionable………
• The measured value for a distance of 5,0 mm was reported as 12,207
mm
• The measured value for the overall length of 250 mm was reported as
131,381 mm
• The measured value for the overall length of 250 mm was reported as
0,031 mm.
© CSIR 2006
www.csir.co.za
Case Study 3 – CMM audit Results (14)
• Solutions
•
•
•
•
Slide 22
CMM training courses through the NLA CMeTSA
More audit parts so as to speed up the programme
Create an improved awareness of measurement & testing principles
Implement an audit programme for large volume CMMs typically used for
vehicle bodies in the automotive industry
© CSIR 2006
www.csir.co.za
Case Study 4 – Local calibration of a ball bar
• There was a requirement in industry to have a ball-bar
•
•
•
Slide 23
calibrated to a specific uncertainty (same as the overseas
calibration service provider)
Initially the CSIR NML turned away the calibration as it could
not perform the calibration at such small uncertainties
Further investigation revealed that the calibration uncertainty
provided by the overseas cal service provider was significantly
better than the ball-bar specification
The manufacturer revealed that the repeatability of the ball-bar
(Breaking it down for transport to cal, building it up during cal,
breaking it down for transport back to factory and building up for
use to calibrate the CMM) was significantly worse than the
calibration uncertainty quoted.
© CSIR 2006
www.csir.co.za
Case Study 4 – Local calibration of a ball bar
(2)
• There was therefore no point in having it calibrated at a low
•
•
•
Slide 24
uncertainty which could not be repeated during use!!
The CSIR NML undertook, as part of the calibration, to perform
an experiment and include the repeatability performance of the
ball-bar into their calibration uncertainty
The resultant uncertainty would still be more then small enough
to support the accuracy required for the calibration of the large
volume CMMs
This would mean the calibration could be performed locally
thereby reducing the costs significantly and reducing the risk of
damage due to international transporting.
© CSIR 2006
www.csir.co.za
Questions??