# Robert Tipton

## Activity

• Hi

+/- 0.005 allows for 0.005 in the X Direction, as well as +/-0.005 in the Y Direction.

This Equates to a Hypotenuse, at a 45 Degree Angle, of 0.007  (Radius) Times 2 = .014 True Position RFS.

Not Considering the Tolerance for the MMC, the 0.002 MMC, would be a severe and dramatic reduction of the total tolerance.

• Hi –

The General Rule of Thumb is +/- 25% of the Sample Size.

Example: Average Sample Size of 100 +/- 25%  =  +/-25,  it is OK to use the same Control Limits.

If the Sample Size is <=74, or >=126, then use Different Control Limits.

These different control limits are sometimes referred to as a Manhattan Skyline.

• Sigma is the Standard Deviation, not the formula you indicated 9 months, 3 weeks ago

• Hello –

If you have a negative CPk, it means you have at least 50% Failures, assuming the formula is correct.

The lower the negative CPk, the more Percent failures.

As an Example;  Negative 1 CPk would be about 99.7% Failures, to the Specification

Then look at the CP Value.  If CP is positive, you probably only need to adjust the mean (…[Read more]

• I have done hundreds of leak testers, with no problem

assure that you have a maximum of 10% gage resolution.

use normal Gage R & R, with Normal Bell Curves.

Use SPC with Normal or Pearson Curve

• Hello –

I would like to provide some additional insight.

1.) Assure that the Gage is Acceptable for the measurements.

1.1) Check Increments and Resolution, Gage Resolution should be less than 10% Resolution, I recommend 5%.

Example: +/- .010 = Total Tolerance of .020.   Increments to be less than .001 = 5% Resolution.