[SH...] Posted June 25, 2020 Share Posted June 25, 2020 I have a part that has concentricity 0.02mm, check the part in cmm I got 0.055. After cleaning the part once again I check the job I got same reading. I told to production supervisor concentricity is out of tolerance but he told it is tool control never change. Again I check the my master sample I got outoff spec. Then I understood I am checking wrongly, I release my stylus system holder from the probe head and check it, it was in good condition, nothing loose. I picked up it and do qualification, then I check the part concentricity shows .005. Why this like happen?.it can be a virus infection to software?? Is there is any method to check software is infected by virus?. Link to comment Share on other sites More sharing options...
[Za...] Posted June 25, 2020 Share Posted June 25, 2020 What did you change when you understood you were checking it the wrong way? If you made changes I would guess that is why you have the different result. Link to comment Share on other sites More sharing options...
[SH...] Posted June 25, 2020 Author Share Posted June 25, 2020 Please sign in to view this quote. I didn't made any changes, just check my master sample ( all dimensions ok job, for reference) it gives wrong results.. Link to comment Share on other sites More sharing options...
[Ch...] Posted June 25, 2020 Share Posted June 25, 2020 Pay close attention to the form value on all of your features. I bet you can narrow it down to one problem feature. I would guess that you are either shanking out or getting bad hits somewhere. Link to comment Share on other sites More sharing options...
[Me...] Posted June 25, 2020 Share Posted June 25, 2020 If you re-qualified your probe and got better results I would suspect your probe system wasn't qualified correctly the first time you checked the part. Link to comment Share on other sites More sharing options...
[SH...] Posted June 25, 2020 Author Share Posted June 25, 2020 Please sign in to view this quote. Form errors are good, lam using 3 mm probe. While checking I observed closely no shanking and bad hit. Link to comment Share on other sites More sharing options...
[SH...] Posted June 25, 2020 Author Share Posted June 25, 2020 Please sign in to view this quote. This is possible,but l have 45 dimensions only one dimension get wrong result. If it is problem in probe, then atleast few dimensions should get wrong result. Link to comment Share on other sites More sharing options...
[Me...] Posted June 25, 2020 Share Posted June 25, 2020 Please sign in to view this quote. Not necessarily. If you probe everything from the same probe angle it will report everything relative to each other using the same probe deviation relative to that angle. If you change probe angles then it will compound the probe deviation. Are you checking the concentric features with different probe angles? Link to comment Share on other sites More sharing options...
[SH...] Posted June 25, 2020 Author Share Posted June 25, 2020 Please sign in to view this quote. Yes, using tip no 3 and 5. Link to comment Share on other sites More sharing options...
[Me...] Posted June 25, 2020 Share Posted June 25, 2020 Ok. You're using a fixed head, not an articulating one. Same principle, though. Link to comment Share on other sites More sharing options...
[Da...] Posted June 26, 2020 Share Posted June 26, 2020 Check to see that the alignment is suitable for the conc. check. Is the concentricity called out to another cylinder that is far away from your feature? Are you using a plane to establish the level , and a circle to establish the alignment for the concentricity check? A small variation on a small face can skew your alignment for the check, very easily. Link to comment Share on other sites More sharing options...
[Ch...] Posted June 26, 2020 Share Posted June 26, 2020 Need more info... Are you using Rotary Table? Scanning/Filtering per Cookbook ? Link to comment Share on other sites More sharing options...
[SH...] Posted June 26, 2020 Author Share Posted June 26, 2020 Please sign in to view this quote. No rotary table, two circle of four points each. Link to comment Share on other sites More sharing options...
[SH...] Posted June 26, 2020 Author Share Posted June 26, 2020 Please sign in to view this quote. It is a counter bore ,two circles, plane for level, circles for clocking and origin. Thanks for the reply Link to comment Share on other sites More sharing options...
[Ch...] Posted June 26, 2020 Share Posted June 26, 2020 I'd probably suggest more points scanning and compare the results...use proper filtering as well... Is the part mechanically aligned to CMM / Stylus as best as possible? good luck ! Btw.... concentricity is phased out from ASME Y14.5 due to it being pretty complex to verify per the definition ,etc. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 26, 2020 Share Posted June 26, 2020 Please sign in to view this quote. Indeed. Four points on each cylinder is not nearly enough data for verifying concentricity as defined in Y14.5. In situations where you're checking the relative positioning between a hole and its counterbore, it's advisable to use a single probe for both. Inter-stylus discrepancy is an error source to be avoided, especially in situations where the Ref Sphere was relocated in between qualification of said styli. Link to comment Share on other sites More sharing options...
[SH...] Posted June 26, 2020 Author Share Posted June 26, 2020 Please sign in to view this quote. It is circle not cylinder, I will keep an eye on it. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 29, 2020 Share Posted June 29, 2020 Please sign in to view this quote. You're only representing it in your program as a circle. But geometrically speaking, the surface in question is cylindrical. (Even if it is very short relative to the diameter, it still has a length.) The Y14.5 standard requires that it pass for all opposing points anywhere along its length. If you only sample 4 points, and they are all at one level, your results will be artificially improved. Link to comment Share on other sites More sharing options...
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