automotive test & measurement case studies saamf roadshow durban csir nml eddie tarnow...
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Automotive Test & Measurement Case Studies
SAAMF Roadshow Durban
CSIR NML
Eddie Tarnow
Metrologist: Torque & Automotive
14 June 2006
Slide 2 © CSIR 2006 www.csir.co.za
Case Study 1 – Seat safety testing
• A testing laboratory was required to perform a yield test on a seat frame to be used in motor vehicles
• The technical specification required that the seat yield atan 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-for-purpose
Slide 3 © 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 4 © 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 loadcell20,1 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 5 © 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 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:-
Slide 6 © CSIR 2006 www.csir.co.za
Case Study 2 – Dimensional measurement of a boot-lid-hinge (2)
M/MENT I/D
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
Slide 7 © 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:-• The balance used for the twice daily checks on the dipping oil was un-
calibrated 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
Slide 8 © 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:• The SAAMF has consulted with them and a number of wide ranging
corrective actions have been identified.
Slide 9 © 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 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
Slide 10 © CSIR 2006 www.csir.co.za
Case Study 3 – Feedback on CMM audit programme (2)
Slide 11 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (3)[PCD 66 mm]
PCD (Ø 66 mm) (Ref 7.4.2)
65,850
65,860
65,870
65,880
65,890
65,900
65,910
65,920
65,930
65,940
65,950
65,960
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05 (1) LAB 05 (2) LAB 05 (3) LAB 06 NML LAB 07 (1) LAB 07 (2) LAB 08 (1) LAB 08 (2) NML
Mea
sure
d P
CD
(m
m)
Slide 12 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (4)[Bore Diameter 90 mm]
Bore dia. (Ø 90mm) (Ref 7.4.3)
89,87489,876
89,881
89,876
89,884 89,884
89,87789,876
89,868
89,876
89,880 89,88
89,885
89,898
89,873
89,858
89,879
89,850
89,860
89,870
89,880
89,890
89,900
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Measu
red
Bo
re D
iam
ete
r (m
m)
Slide 13 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (5)[Distance 5 mm]
Distance (5 mm) (Ref 7.4.7)
4,975 4,9754,973
4,9744,975
4,973
4,971
4,976
4,972
4,974 4,974
4,961
4,987
4,977
4,9724,973
4,950
4,955
4,960
4,965
4,970
4,975
4,980
4,985
4,990
4,995
5,000
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Dis
tan
ce M
easu
red
(m
m)
Slide 14 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (6)[Distance 250 mm]
Distance (250 mm) (Ref 7.4.8)
250,037
250,033
250,031
250,020
250,032
250,024
250,031
250,027
250,040
250,036
250,039
250,031
250,041
250,030
250,000
250,010
250,020
250,030
250,040
250,050
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Dis
tan
ce M
easu
red
(m
m)
Slide 15 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (7)[Outside Diameter 14 mm]
Outside dia.(Ø 14 mm) (Ref 7.4.9)
14,041
14,038
14,035 14,035
14,02914,028
14,036
14,04414,045
14,037
14,039
14,036
14,043
14,034
14,010
14,020
14,030
14,040
14,050
14,060
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Dia
mete
r M
easu
red
(m
m)
Slide 16 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (8)[Outside Diameter 28 mm]
Outside dia.(Ø 28 mm) (Ref 7.4.10)
28,047
28,040 28,03928,043
28,031
28,078
28,04328,039
28,047
28,040 28,042 28,043
28,001
28,071
28,048
28,056
28,040
27,940
27,960
27,980
28,000
28,020
28,040
28,060
28,080
28,100
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Dia
mete
r M
easu
red
(m
m)
Slide 17 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (9)[Concentricity]
Concentricity (Ref 7.4.11)
0,008 0,008 0,009 0,009
0
0,008 0,007 0,0060,004 0,004
0,008 0,008
0,057
0,067
0,021
0,008
0,000
0,010
0,020
0,030
0,040
0,050
0,060
0,070
0,080
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Co
ncen
tric
ity M
easu
red
(m
m)
Slide 18 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (10)[Roundness of Bore]
Roundness of Bore (Ref 7.4.4)
0,012
0,031
0,005
0,013
0,004
0,03
0,010
0,033
0,014
0,020
0,0100,009
0,020
0,028
0,010
0,0035
0,0085
0,0135
0,0185
0,0235
0,0285
0,0335
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
Ro
un
dn
ess M
easu
red
(m
m)
Slide 19 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (11)[Included Angle]
Included Angle (Ref 7.4.6)
37,000 36,926 36,936 36,956 36,936 36,933 36,927
33,760
36,920 36,966 36,943 36,925 36,89437 36,903 36,967 36,954
32,000
33,000
34,000
35,000
36,000
37,000
38,000
NML LB 01 LAB 02 NML LAB 03 LAB 04 NML LAB 05(1)
LAB 05(2)
LAB 05(3)
LAB 06 NML LAB 07(1)
LAB 07(2)
LAB 08(1)
LAB 08(2)
NML
An
gle
Measu
red
(d
eg
ree)
Slide 20 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (12)
• Problems experienced:• 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
Slide 21 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (13)
• Conclusions:• 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.
Slide 22 © CSIR 2006 www.csir.co.za
Case Study 3 – CMM audit Results (14)
• Solutions• 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
Slide 23 © 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 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.
Slide 24 © 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 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.
Questions??