Pressure Test Method Results have a significant effect on my sample size and capability, how to avoid?

qLienceStats — Fri, 06 Dec 2024 07:58:56 GMT

Hello dear JMP community

I will first explain the test method (no need to comment on whether it is right or wrong because this is what I got). The purpose is to detect a leakage.

Measurement process

Part is mounted to a pressure station
Pressure station rotate a vacuum pump x times to create a vacuum (atmospheric pressure is approx. 1000mbar)
Pressure p1 is sampled at time t1
After 15 seconds p2 is sampled at t2

Specification

700 mbar ≤ p1 ≤ 750 mbar
p2 - p1 ≤ 4 mbar

Situation

If there is a leakage then the result can differ a lot from normal observations.

Challenges
This cause two challenges:

This have a very high impact on my Cpk and Ppk, which i have a requirement for.
I hoped I could use the continonus response to model my system but this is just creating to much noise and creating a lot of "outliers". When shifting to a binary response then my Power analysis for one sample proportion require a lot of sample to detect a difference in scrap.

Anyone with some good ideas to how I could solve this puzzle?

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Pressure Test Method Results have a significant effect on my sample size and capability, how to avoid?