K
Kelly W
We run a test that has two steps. First, the sample is exposed to a controlled damaging influence for 16 hours. Second, a numeric (distance) measurement is made of how much damage the sample sustained. There are 2 of these distance measuring devices, and they are used by 6 different operators. The product that we test tends to exhibit high response variability between pieces of the same production, so a standard test uses 6 pieces. There is no "standard material" that can be run through the measurement system.
The people who ask us to do this test also occasionally ask, "What's your Gauge R&R on that test?" I've been mumbling for a couple of years something about GRR not being appropriate, but now I need to do one of 3 things:
1. Figure out how to do a GRR on this measurement system.
or
2. Explain accurately why GRR is not an appropriate analysis of the system.
or
3. Find an alternative analysis that provides useful information about the system.
It shouldn't be hard to do a GRR on the instrument that provides the numeric observation of the damage (an LVDT with associated analog-to-digital hardware). But that will tell me nothing about the variability introduced by the controlled damaging process.
It's clearly a destructive test, but all the discussions & articles I've read on destructive testing GRR still only apply to a single instrument, which happens to destroy the sample as it is acquiring its numeric value.
An analogous measurement system that I can imagine might be a "ballistic indent" - propel a steel ball at high speed into an aluminum plate, then use a depth gauge to measure the dent. The propulsion system could have, say, angle or speed variations, and the depth gauge could have its own variations. But the customers get a single result of the test, depth of dent, and so they are essentially asking "What's the Gauge R&R on the [ball propulsion-depth gauge] measurement system?"
I can't find anything on MSA for a multi-phase, destructive test - any suggestions?
The people who ask us to do this test also occasionally ask, "What's your Gauge R&R on that test?" I've been mumbling for a couple of years something about GRR not being appropriate, but now I need to do one of 3 things:
1. Figure out how to do a GRR on this measurement system.
or
2. Explain accurately why GRR is not an appropriate analysis of the system.
or
3. Find an alternative analysis that provides useful information about the system.
It shouldn't be hard to do a GRR on the instrument that provides the numeric observation of the damage (an LVDT with associated analog-to-digital hardware). But that will tell me nothing about the variability introduced by the controlled damaging process.
It's clearly a destructive test, but all the discussions & articles I've read on destructive testing GRR still only apply to a single instrument, which happens to destroy the sample as it is acquiring its numeric value.
An analogous measurement system that I can imagine might be a "ballistic indent" - propel a steel ball at high speed into an aluminum plate, then use a depth gauge to measure the dent. The propulsion system could have, say, angle or speed variations, and the depth gauge could have its own variations. But the customers get a single result of the test, depth of dent, and so they are essentially asking "What's the Gauge R&R on the [ball propulsion-depth gauge] measurement system?"
I can't find anything on MSA for a multi-phase, destructive test - any suggestions?