MSA on an in-line automatic X-ray thickness measuring gage

[pepe76]

Please help me,

We're manufacturing cold rolled steel strips. Should I evaulate measuring system analysis to an automated in-line X-ray thickness measuring gage. The gage controlls the milling process.

 

[Bev D]

well, yes you should perform an MSA on the system. This is a common dilemma for manufacturing - measuring systems are 'sold' based on their accuracy. the more techologically advanced, the more hype regarding their ability. Frequently these systems are appropriate and properly ddeployed, so an MSA merely confirms this. But too often these systems are not propely deployed and they fail an MSA. there is no way to predict the capability of a system without data. So yes, if the measurement is critical to ensure quality of your product then you should perfrom an MSA.

why would you consider not performing the analysis?

 

[pepe76]

I read it in a GM Measurement System Specification.:
"In-line automatic gages are of 4 types:

A) Pre-process compensating (feed forward). The gage measures the workpiece before processing and "tells" a
subsequent process step how much stock to remove.
B) In-process controlling. The gage measures the workpiece as it is being processed. The gage controls the amount of
stock removed and typically stops the process at a preset point.
C) Post-process compensating (feed back). The gage measures the workpiece made in a previous process step, "tells"
that process step how much to change the stock removal on subsequent workpieces, and accepts or rejects the
measured workpiece.
D) Post-process sorting. The gage measures the workpiece made in a previous process step and accepts or rejects the
workpiece.
Generally, gage types A and B should not be the Gage of Record; gage types C and D should be the Gage of Record.
Gage types A, C, and D require Type-1 (see section 2.2.6.1) and Type-3 (see section 2.2.6.3) studies; gage type B does​

not."

I think this gage is type B.

 

[Bev D]

even tho it is not required (since the gage is used for in process control) by some standard, the gage is being used to adjust the process and if its wrong it could produce non conforming parts. for their own protection they should perform an MSA to ensure they are truly controlling their process.

Customers often don't care about their supplier's yield; they care more about the final inspection system that 'guarantees' no nonconforming material will be shipped. But the supplier probably does care about yield as it directly effects profits and ability to deliver on time.