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During a conversation with a colleague the other day the subject of verification of out of tolerance dimensions came up.

Company requirements state that inspection tools used to verify dimensions must be capable of measuring 10X the precision of the dimension called out on drawings
Case 1: Drawing specifies a dimension to be .245 -.250 and you use a micrometer capable of measuring to .0001 increments. When inspecting the part you get a measurement of .2501, should the part be rejected or accepted?
Case 2: Drawing specifies a dimension to be .245 -.250 and you use a CMM to verify part dimensions. The CMM reports the part measurement to be .25001, should the part be rejected or accepted?
My stance is that to verify that the dimensional value meets the tolerance on the drawing it makes sense to use tooling capable of measuring 10X precision of the dimensions called out on the drawing. Without using 10X precision tooling then you get rounding error in the tool, correct? It seems to me that by being required to use 10X precision tooling I must verify out to that level of precision the part meets the drawing. My colleague feels that I have exceeded the intent of the drawing by measuring out to 4 places and should not reject the part. In the case when using the CMM I feel that you should truncate the dimensional values to 10X precision of the drawing dimensions and that any characters after the 10 precision should be ignored.
I have also been part of conversations with different opinions that if you specify a dimension on a drawing as .24 - .25 the criteria for part acceptance is different than if I specified the dimension as .240 - .250
Any thoughts?
Thanks

18 days ago

2012-11-19, 09:08 AM	#1
huangyhg 超级版主注册日期: 04-03 帖子: 18592 精华: 36 现金: 249466 标准币资产: 1080358888 标准币	During a conversation with a colleague the other day the subject of verification During a conversation with a colleague the other day the subject of verification of out of tolerance dimensions came up. Company requirements state that inspection tools used to verify dimensions must be capable of measuring 10X the precision of the dimension called out on drawings Case 1: Drawing specifies a dimension to be .245 -.250 and you use a micrometer capable of measuring to .0001 increments. When inspecting the part you get a measurement of .2501, should the part be rejected or accepted? Case 2: Drawing specifies a dimension to be .245 -.250 and you use a CMM to verify part dimensions. The CMM reports the part measurement to be .25001, should the part be rejected or accepted? My stance is that to verify that the dimensional value meets the tolerance on the drawing it makes sense to use tooling capable of measuring 10X precision of the dimensions called out on the drawing. Without using 10X precision tooling then you get rounding error in the tool, correct? It seems to me that by being required to use 10X precision tooling I must verify out to that level of precision the part meets the drawing. My colleague feels that I have exceeded the intent of the drawing by measuring out to 4 places and should not reject the part. In the case when using the CMM I feel that you should truncate the dimensional values to 10X precision of the drawing dimensions and that any characters after the 10 precision should be ignored. I have also been part of conversations with different opinions that if you specify a dimension on a drawing as .24 - .25 the criteria for part acceptance is different than if I specified the dimension as .240 - .250 Any thoughts? Thanks 18 days ago __________________ 借用达朗贝尔的名言：前进吧，你会得到信心! [url="http://www.dimcax.com"]几何尺寸与公差标准[/url]