The Fundamentals of Gauge Block Specifications

Certificate and Serial Number
• It is an absolute necessity that each gauge block carries its own Serial Number for calibration purposes and, to determine the actual size to the closest millionth of an inch
• A Certificate of Accuracy, traceable to NIST, is normally furnished with each gauge block set and individual gauge block (unless otherwise noted)

Go/No-Go gauging is an inexpensive but, very accurate measurement of hole diameter. Go/No-Go plug gauge assemblies consist of a Go gauge pin, No-Go gauge pin, handle & 2 bushings. The Go gauge pin, (tolerance plus) represents the minimum size of the hole to be measured. The No-Go gauge pin, (tolerance minus) represents the maximum size of the hole to be measured. The hole is considered in tolerance if the Go goes into the hole & the No-Go does not.

Statistical Process Control (SPC): Is a quality control system designed to provide product/process quality information during a product/process run. SPC is also used after the fact to provide
an in-depth analysis of product/process quality capability. The term “SPC” is generally used as an umbrella concept to cover quality systems that rely on statistical analysis and charting using only a portion of the available data (i.e. part feature measurements) to predict the overall quality of the products/process. This contrasts with the old method of making a batch of parts, sending them to the QC room for inspection, and then repairing or throwing out the reject parts. In the early days of SPC, charting and statistical calculations were done by hand using a pencil and paper. Today a large assortment of electronic tools is available to reduce the cost of gathering data.