MSA - Can Regular Calibration Replace Bias, Linearity and Stability Studies?

D

darkafar

#1
If my measuring equipment is calibrated traceable to international standard, at regular intervals specified by the manufacture or certain international standard, do I have to do bias, linearity and stability? I think bias and linearity can be guaranteed by the calibration certificate, and stability can be guaranteed by regular calibration. Am I right?
 

Miner

Forum Moderator
Staff member
Admin
#2
If my measuring equipment is calibrated traceable to international standard, at regular intervals specified by the manufacture or certain international standard, do I have to do bias, linearity and stability? I think bias and linearity can be guaranteed by the calibration certificate, and stability can be guaranteed by regular calibration. Am I right?
Calibration does assess bias and linearity, but only using a single point measurement and in ideal labratory conditions. Bias and Linearity studies use multiple readings at each size in the actual working environment. Bias may be different in a different environment In addition, the analysis portion of Linearity is not provided by the cert.

Calibration does not assess stability at all. In the application, you want to know the stability of the gage in the work environment where the temperature and humidity, as well as vibration and power supply, etc. may change throughout the day.

In short, calibration does not eliminate the need for these studies.
 
D

darkafar

#3
So the main obstacle to this replacement is the gap between working environment and the ideal laboratory conditions. So if I can narrow this gap, my assumption can still have a chance to be correct? So if my actual working environment is in an air-conditioned clean room, my assumption can be acceptable?
 

Helmut Jilling

Auditor / Consultant
#4
If my measuring equipment is calibrated traceable to international standard, at regular intervals specified by the manufacture or certain international standard, do I have to do bias, linearity and stability? I think bias and linearity can be guaranteed by the calibration certificate, and stability can be guaranteed by regular calibration. Am I right?

Calibration only establishes whether the gage is accurate, or if there is a bias in the readouts. It does not establish the bias over the range (linearity), unless you do many readings. It does not establish the bias over time (stability) unless you calibrate very frequently, like daily.

These studies serve a different purpose than basic calibration.
 

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