Laser Mike Insturment - MSA - Which (Bias, Linearity, Stability, R&R) are applicable?

[manpreet]

Can some one guide me which requirements of MSA (Bias, Linearity, Stability, R&R) are applicable to Laser Mike. It is a instrument which measure the OD of tube with the help of two lasers & axis system.

[Jim Wynne]

Originally Posted by manpreet

Can some one guide me which requirements of MSA (Bias, Linearity, Stability, R&R) are applicable to Laser Mike. It is a instrument which measure the OD of tube with the help of two lasers & axis system.

All are applicable. "Bias" is just another word for "error"; "linearity" refers to uniformity of bias across the expected measurement range of the instrument; "stability" is a measure of how well a gage maintains its level of bias (or lack thereof) over time, and R&R is used to verify that the system is appropriate for the application.

[manpreet]

Hello Jim Wynne

I tried to Check R&R on this. But i think practically it is not possible, every time a got different readings beacause of Point of measurement or flexibility in tube.
I can use a solid(iron) pcs for R&R but during R&R actual pcs must be used as per msa manual. what should i do

regards
manpreet

[Jim Wynne]

Originally Posted by manpreet

Hello Jim Wynne

I tried to Check R&R on this. But i think practically it is not possible, every time a got different readings beacause of Point of measurement or flexibility in tube.
I can use a solid(iron) pcs for R&R but during R&R actual pcs must be used as per msa manual. what should i do

regards
manpreet

It sounds like the R&R you did is trying to tell you something--it served its purpose. Now you know that there are sources of variation that can produce measurement errors, which might mean that the laser mic is the wrong tool for the job. On the other hand, if the measurements aren't reproducible due to inherent part variation (or not being able to hit the same spot on the part each time) you might want to try the "Practices for Non-Replicable Meaurement Systems" as shown in the AIAG MSA manual (3rd Edition, page 143).

[Hershal]

You may well have other sources of error creeping in by the laser itself. For example, have you also considered the effects of refraction, reflection, and diffusion (all are effects that affect lightwave measurement) on the beam?

This is in addition to any effects from alignment errors and so forth.

Also, don't forget to include the measurement uncertainty from the accredited caliration cert for the instrument.

Hershal