September 22, 2023

Industrial standards require all fabrication to calibrate every inspection, measuring, test equipment and devices against certified equipment with a valid relationship to recognized standards (e.g. ISO 9002 etc). Therefore, every fabrication should operate with the balance between “in-house calibration” and “external calibration”.

In-house calibration with reputable precision comparator and dedicated engineer, will save you costly rejects and complaint from customers. External calibration, on the other hand is also practical. You simply outsource the process to outside calibration lab which are trusted, reputable & accredited, but with uncertain lead time.
To balance out the trivial matter of calibration, here are some rule of thumb which you may consider :

  1. Application & working environment
    Micrometers or dial gauges used in inspection lab and open yard will experience different treatment by its multiple operators of one QC spec. Harsh environment and busy fabrication queue will calls for frequent set up and immediate solution. Hence, a dedicated in-House QC lab with universal linear measurement devices will help for prompt maintenance and tailored services.

For smaller machine shops with uncertain contracts, the most economical approach is definetely to hire a reputable calibration service.

  1. Accuracy, acceptable tolerance standard:

Depends on your customer’s preference, each ISO, UKAS, JIS, DIN, ASTN and KAN, demand requirements which are quite similar but certainly needed on specific market. Hence, how important is accuracy to you?. Establishing an in-house calibration service can add up to a large investment as you have to acquire facilities, equipment, and trained personnel for performing calibration that is up to the standard.

For instance;

ISO/IEC 17025 specifies the general requirements for the competence to carry out tests and/or calibrations, including sampling. They are applicable to calibration vendors who perform tests and/or traceable calibration for others. CMIIW, as your manufacturing standards of medical equipment quality system is certified to ISO 13485, the ISO 17025 accreditation means for internal calibration is not required. However, if your In-House calibration or QC lab do own such certificates, you might as well offer a calibration services towards other parties as a part of your business leverage.

3. User comforts influence productivity:

User comfort and confidence towards their caliper’s accuracy and dial gages repeatability surely relates to a productivity. A good calibration machine offer user friendly set up with both manual and automatic control system as calibration process often requires manual tweak and repairs to cater user preference on multiple type of gages.

4. There is no “all for one” certification standards for calibration labs:

Keeping those gages calibrated in accordance to quality standards like ISO 9000 is an important task. Every company has different circumstances, you can set a 35% percentage on bi-annual calibration by an outside lab or even 50:50. Either way, there is no warranty that your calibration vendors will stay reliable or the operators stay diligent. Investing on In-House calibration will facilitate you to control the work flow and documentation procedure to your needs.

5. “See to believe” & references:

When considering a calibration vendors, the reputation is also important.  You have to visit and confirm their test equipment and to what standards can their test methods be certified (e.g., ISO, MIL, KAN, UKAS, ANSI). Investigate who and what quality control methods are in place?  You also need to assure their level of clean room facility, what are the control tolerances on temperature and humidity, and how is the equipment protected from effects of outside vibration.

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