Hi Chiheb G
I am an IATF auditor. MSA is required for your weighing machines, unfortunately. There are 2 possibilities that they can be exempted:-
1) If your relevant customers give written approval that MSA is not required
2) it is for secondary measurement. Example, for some very small parts, counting by hand is the primarily method, but you want to use the weighing balance to do a quick cross-check.
In fact weighing machines can be highly sensitive. In some countries, even legal requirement is involved. Example, weigh-bridge calibration in many countries are only to be calibrated by government metrological labs.
Anyway, calibration and MSA have same purpose but different scope. Full MSA include: repeatability, reproducibility, bias, stability and linearity. They combined to tell how reliable is the measuring system. Calibration measures the bias and some degree of lineality. If you are not dealing with North American customers, GR&R is normally acceptable in place of MSA. GR&R = repeatability + reproducability only. From GR&R results, you will see some indications of where the problem lies. If the error is high on EV, equipment is having problem. If AV is high, there are problems with the appraisers (people), method or measuring conditions. You should read up the MSA reference manual by AIAG. But there is something new coming form IATF, as we speak. Hope to update this at a later date when i have gone through the lessons.
