The decision on recalibration frequency interval must be a local decision based on local usage and environmental conditions. For Hardened Gages, Hardened Tooling, GO/NOGO Gauges, and Reference Connectors; recalibration frequency is established by determining the usage of the device and its likely wear-out point. It is an engineering decision which must be made locally in each application. Be ready to provide a logical support for your decision to your superiors/customers.
According to ISO 17025 (2005), Paragraph 184.108.40.206:
"A calibration certificate (or calibration label) shall not contain any recommendation on the calibration interval…"
There is an exception when a re-calibration date is specifically requested by a customer, but the customer must specify the re-calibration interval. The calibration company is forbidden from unilaterally assigning this value.
There is not:
a. Any specified frequency for recalibration of hard gages, GO/NOGO gauges, or Reference Connectors.
b. A manufacturer specified frequency for recalibration of hard gages, GO/NOGO gauges, or Reference Connectors.
c. An industry rule-of-thumb for frequency for recalibration of hard gages, GO/NOGO gauges, or Reference Connectors.
I can supply some guidelines:
a. Hardened Gages, Hardened Tooling, GO/NOGO Gauges, and Reference Connectors are made of a material with hardness usually in excess of Rc58. This hardness gives excellent abrasion resistance.
b. Test pieces have materials which range from soft plastic to hardened steel. The abrasive properties of the different types of materials varies greatly and must be considered locally
c. Hardened steel contains a possibility of changing size over its first year of existence. This change is very small and is identified in inches per inch (mm/25.4mm). This is more noticeable in pieces over 1 inch (25mm) in size. The small amount is usually too small to notice in parts where the tolerance is larger; however, in gages where the tolerance is small, the change can be noticed.
Using the above criterion; in my opinion:
a. All hard gauges, if not calibrated more frequently, should be tested after the first year to evaluate for Hardened Steel Growth.
b. Determine a logical number of pieces needed to wear out the Hardened tooling by good sound engineering logic based on: - How many pieces are tested a day/month/year? - Is the tested piece soft plastic or hardened steel? - Is the test piece/environment clean or dirty?
c. After the first calibration; check the results for wear indicators. Determine if the calibration interval needs adjusting. After the second recalibration; evaluate again for wear indicators and adjust the interval again if needed. Repeat the process over the life of the gauge.
d. For best results and economy; each Hardened Gage, Hardened Tool, GO/NOGO Gauge, or Reference Connector requires individual evaluation for calibration frequency. A general rule cannot be established.
We offer Calibration Services:
If you need your gages calibrated please allow us to provide a quotation for Calibration Service.
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Remember that I am only offering a studied opinion, not a rule or official statement. This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. Be ready to provide a logical support for your decision to your superiors/customers.
Original Posting: 10/23/2015
Last Revision: 11/9/2020
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