Miner,
Thanks for the explianation, I have 1 more question.
When calculating the %GR&R against TV it is 100(R&R/TV)
When calculating the %GR&R against Tol it is 100(R&R/(Tol/6))
Why is the Tolerance divided by 6
There are a lot of equations floating around, and rather than tell you that they are wrong I am going to give you the MBB's favorite answer: "It depends".
AIAG started it when they revised the MSA manual from the 2nd edition to the 3rd edition. They decided to
simplify the equation by changing how the 6 multiplier was used in the K constants and the formulae.
Bottom line: the change amounted to whether you used (6*StdDev)/Tol or StdDev/(Tol/6). The 6 was hidden in the revised K constants. Some spreadsheet equations stayed with the 2nd edition K constants and moved the 6 into the formula, so it got confusing.
Use the Ford MSA software validation data set to validate your spreadsheet, and there should be no concerns. If I have time later, I'll link to it, but you can also search for it within this forum.