Automotive Test & Measurement Case Studies SAAMF Roadshow Durban CSIR NML Eddie Tarnow Metrologist:...

Automotive Test & Measurement Case Studies

SAAMF Roadshow Durban

CSIR NML

Eddie Tarnow

Metrologist: Torque & Automotive

14 June 2006

© 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


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)


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.


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:-


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



• 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



• 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.


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


Case Study 3 – Feedback on CMM audit programme (2)


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)


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)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Dis

tan

ce M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Dis

tan

ce M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Dia

mete

r M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Dia

mete

r M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Co

ncen

tric

ity M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

Ro

un

dn

ess M

easu

red

(m

m)


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


LAB 05(2)

LAB 05(3)


LAB 07(2)

LAB 08(1)

LAB 08(2)

NML

An

gle

Measu

red

(d

eg

ree)


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



• 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.



• 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


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.


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.

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