Chapter 9. Simplified Gauge Verification

What you will learn in this chapter is how to determine gauge error and how to correct this error if excessive. When a problem surfaces, one of the first things that must be done is to get good data/measurements related to the problem. The issue of gauge accuracy/repeatability/reproducibility applies everywhere a variables data measurement (decimals) is taken.

Before we use data, we must be satisfied that the data are accurate. One of the most frequent sources of error is the device used to measure the product or process. This device can be as simple as a ruler or as complex as a radiation sensor.

Data error can give us a false sense of security—we believe that the process is in control, that we are making acceptable product—or cause us to make erroneous changes to the process. These errors can be compounded by the difference between the gauges used by the supplier and those used by the customer or by variation among gauges within a manufacturing plant.

In Six Sigma projects, the use of this simplified gauge verification tool often gives an insight that allows for big gains with no additional efforts. In the DMAIC process, this tool can be used in the Define, Measure, Analyze, Improve, and Control steps.