Calibration, should we.... Go-No-Go, thread, pin, and ring gauges



We are a small machine/fab shop that specializes in CNC and Conventional Machining processes. We are seeking QS9000 certification in July. We do not supply any parts to the Big 3 as of yet, but hope to in the near future. What I having a problem with is that of Calibration. We have calibrated all of our instruments here such as calipers, micrometers, indicators, tapes and rulers, etc. However, in a machine shop type of atmosphere, there are also other types of gauges. These gauges are a concern to me. I am referring to Go-No-Go gauges, thread gauges, pin gauges, and ring gauges. We do not have ANY of these things calibrated as of the moment. The registration audit is coming around and the pace is picking up around here. What I need to know is, DO THESE GAUGES HAVE TO BE CALIBRATED? I mean, these gauges are used to check certain finish dimensions on products (like threads, hole diameter, etc.). Please clear the "fog" in my eyes concerning this subject.
Thank You,

Joe W. Guy,
QS9000 Administrator


Hi Joe
As my understanding the auditors will not accept if go-no-go gauge is not calibrated. What I did go-no-go calibration in my company,we established tollerance each certain point and measure them with calibrated equipment. If the result of measurement is within the tollerance, then the calibration sticker will be identified on the gauges.

barb butrym

Quite Involved in Discussions
The answer is in the use. Are they used for reference dimensions that are checked again later, or for final acceptance? You need to address each one and determine its effect on the quality of the product/end item, and identify it as such...DON"T come after me...I use "it" in "All yellow inked" plug gauges are for xxxxxx and require verification with a calibrated instrument prior to use. (they may look for evidence of that verification depending on the criticality of the measurement, be prepared) All red inked gauges are used for measurements that do no effect the quality of the end item. Just make sure the part of the gauge you ink isn't the working part, cause it will wear off.....LOL Some will have to be calibrated....look closely, and be honest and be prepared to discuss (best to justify with a record /my consultants hat on that one)...they will look closely at that.
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