With any measurement instrument or tool used to qualify product, it is mandatory that the tool or instrument be 100% functional and measure per the appropriate specifications when used. A manufacturer’s calibration can perform both functions. A system inspection and calibration verify that the instrument is functional and that the instrument was and is measuring accurately, while routine maintenance helps to ensure the instrument will continue to function going forward.
While an instrument’s self-calibration or internal calibration is convenient for routine spot checking and verification, it should never replace a full calibration performed by an unbiased and trained professional.
Overreliance on self-calibration comes with risks. For instance, internal personnel tasked with equipment maintenance may not be properly trained to maintain or spot potential issues with the instrument. This could leave the instrument in a “non-functioning” state while giving the end user the impression that it is functioning and producing accurate measurements.
High product volume and pressure to deliver make internal personnel more likely to clear equipment for use on the production floor even if performance is compromised.
Using an outside facility for calibration puts the assessment of the instrument in the hands of someone deeply familiar with those processes, who can spot potential measurement and calibration issues, and, maybe more importantly, is outside the sphere of influence of the production environment.
At the same time, it is important to make sure that any outside calibration facility that is contracted for your calibration needs is equipped to verify all types of measurements that that equipment performs. A top-notch calibration facility for RF or copper cable test equipment may not be well-equipped to verify the functionality and accuracy of optical test equipment. In this case, an instrument may be returned with a sticker that indicates it is calibrated, but all parameters may not have been tested (or may have been tested improperly).
A manufacturer’s calibration ensures that properly trained and experienced personnel are performing the inspection and calibration of the instrument. The accuracy of all the necessary measurements is verified and, if necessary, adjusted back within the specifications of the device and a report detailing the findings of the calibration is returned with the equipment.
Calibrations, even when exhaustive, are performed under specific conditions and many times with very specific and limited setups, which may not represent the conditions that the instrument will experience when measuring. System inspection and maintenance help to ensure that when put back into the field the instrument will measure and perform as expected. If a non-manufacturer’s calibration is selected, it is still advised to have routine maintenance and inspection performed on fiber optic equipment.
The results obtained during production testing are only as accurate and valid as the equipment used to obtain them. As such, the test equipment should be properly maintained and verified by trained personnel to guarantee full functionality and accuracy.