Not a Calibration Expert but questioning in-house calibration method.

[MarcoSimone]

So, I'm new to a small machining company and we do in-house calibration for common handheld and bench/surface plate top measuring devices. (Micrometers, Calipers, Drop Indicators, Height Stands, Bore Gages,...etc)

When I look at our calibration database records, I see all of our in-house calibration results are just deviations & not actual results to the various standards used.
(Nearly all results in database are 0.000, 0.0000, +0.0001, -0.0001, .... and always within tolerance range) Plus the results recorded for any gage calibration is just one result for the entire calibration of that gage at that period. I have serious concerns whether or not we are doing calibration correctly at all as it seems too simplistic.
I'd expect multiple deviation results from the various size masters measured. Some of these gages can be used in multiple manners, ID, OD, Depth, Step..... Yet, there is only one result recorded.

Looking at our calibration instructions for various devices they states to take verify measurements at various increments across the range of the gage. (0.100, 0.500 1.000, 3.000, 5.000, 7.000 & 7.950). So I'd expect there to be seven results recorded in the database for that device calibration. Yet, only one deviation result recorded of 0.0000 recorded & calibration result Pass. Our company is ISO 9001 registered and apparently these calibration methods are acceptable & has passed their audits.

When they send more sophisticated devices/equipment out for calibration they do receive thorough calibration certificates what I expect a calibration record to appear, with As Found, As Left values at each interval w/actual readings of that interval (i.e. 1.0002). Apparently they are saving a lot of money doing the calibration in house. The in-house calibration tech has been working there for 3+ years and says this was the way he was trained to conduct calibrations, by the prior management group.

I'm new and a bit uncomfortable to question what they are doing when I'm not certain myself, what is proper measuring device calibration. I will do more research but found this forum group & thought someone may be able to offer quick insight & advice. Thanks for anyone who take time to read this.

 

[Sidney Vianna]

Our company is ISO 9001 registered and apparently these calibration methods are acceptable & has passed their audits.

Do not assume anything. Not clear why you decided to investigate the internal calibration records. Was that part of an internal audit? Have you seen the technician actually performing a calibration job? Does he verify the “as-received” condition? Is he competent to perform such calibrations?

He might be short cutting the calibration process to save time.

Does your organization have returned products from customers for dimensional failures? Are you really inspecting dimensions to the tenth of a thousand?

There is a lot of context we are not aware of at this point.

 

[dwperron]

I'm new and a bit uncomfortable to question what they are doing when I'm not certain myself, what is proper measuring device calibration. I will do more research but found this forum group & thought someone may be able to offer quick insight & advice. Thanks for anyone who take time to read this.

A lot of smaller (and older) labs still cling to "cal lab" practices, and they have a habit of taking shortcuts.
Consider reporting results. A lot of labs operate under the assumption that if a unit passes calibration then you can assume that it meets the "fitness of purpose" requirement of ISO (operating within the specifications), so they do not need to report the actual results. This saves them time and money. It also meets the requirements of ISO 9001 and family.
These labs will only report calibration results when the unit is found to be out of tolerance, also meeting the ISO 9001 requirement.

 

[MarcoSimone]

A lot of smaller (and older) labs still cling to "cal lab" practices, and they have a habit of taking shortcuts.
Consider reporting results. A lot of labs operate under the assumption that if a unit passes calibration then you can assume that it meets the "fitness of purpose" requirement of ISO (operating within the specifications), so they do not need to report the actual results. This saves them time and money. It also meets the requirements of ISO 9001 and family.
These labs will only report calibration results when the unit is found to be out of tolerance, also meeting the ISO 9001 requirement.

Excellent, I can accept & run with this response & not stir pot. If it's ISO compliant it's with us at moment & we can fly the flag. Management is primarily on the "does it meet requirements", if yes, move on. We have plenty of field issues but nothing to the point of any major system breakdown evidence. I suspect old "cal lab" practices is how we've been operating for 30 years+, as this coincides with duration of our Cal lab resource make up & a Cal. Lab from that time frame is how current resources cut their teeth before arriving in our company. Failed calibrations do record more information. Yes, source info for question is from new blood in internal audit activity, we just needed to check into whether there is significant concern or not. Thanks