When are Fixtures Calibrated
Fixtures developed by RI are calibrated before they leave the RI facility and are good for the lifetime of the fixture. RI's factory has the equipment, tools, and instruments to do the best job generating the calibration data. Shipping the fixture adds very little stress to the fixture itself. Actually, opening and closing the fixture flexes the cables and has more opportunity for offsetting the calibration than the shipment itself.
The only reason we would calibrate a fixture is if it had just been serviced and parts were replaced.
Here are some things to consider:
- Removing the DUT board and replacing with it with the calibration boards provides a chance to have something go wrong. The very act of calibrating a fixture exposes it to some danger of damage.
- If something were damaged during shipment (unlikely unless the box is crushed) then calibrating it would actually HIDE the problem and make it far more difficult to find. We ALWAYS diagnose the problem and fix it before we calibrate the fixture.
- The idea of calibrating a fixture, or any instrument, "just in case" is not good methodology. There is usually a small shift in the baseline of your measurements that can affect correlation and limits when you re-calibrate, even if everything is working perfectly.
RI strongly recommends measuring some known parts with your fixture before spending a lot of time calibrating it, or even validating it. By cycling through the Calibration DUT boards, you will be exposing the fixture to the possibility of damage. It just isn't a good idea to do that unless you have a positive indication to suspect the fixture is malfunctioning.