CMM inspection for Cylindricity
CMM inspection for Cylindricity
(OP)
We are producing a pinion, approx. 30mm long that calls for the cylindricity of the I.D. to be within 7 microns. Using a CMM we initially programmed the probe to scan in a spiral motion throughout the length of the pinion I.D. (except the first millimeter on each end). The results on six pieces were 8-12 microns. Our customer informed us that the check the parts with eight hits at three points in the I.D. Using their methodology the results were from 2.5-6 microns. Which is the proper methodology, and why the varying results? Is it due to the scanning throwing out the upper and lower readings?
Regards,
Tom Klosowski
Delta Research Corp.
www.delrecorp.com





RE: CMM inspection for Cylindricity
RE: CMM inspection for Cylindricity
I guess my main question was two-fold; which methodology would be the preferred, and why the great variance between the two checks. We are concerned that variance may be due to a software issue that could raise its head in other areas, but if the variance we saw is normal we can just go on with life and chalk it up to experience.
Regards,
Tom Klosowski
Delta Research Corp.
www.delrecorp.com
RE: CMM inspection for Cylindricity
By scanning in a spiral motion, you were checking to see how closely the actual part matched to the theoretical profile of a cylinder. With their method you were checking the roundness of three circle and the concentricity of those circles. The results were much better, which is to be expected, with the second method.
RE: CMM inspection for Cylindricity
I appreciate your help.
Regards,
Tom Klosowski
Delta Research Corp.
www.delrecorp.com
RE: CMM inspection for Cylindricity