Go No-Go Gages (Hard Gaging)

Go No Go Gages (fixed limit gages) are adopted for checking parts produced by mass production. Go no go gages have the advantage that they can be used by unskilled workers because the go no go gage is considered one of the simplest forms of pass/fail attribute inspection. If the go fits and the no-go does not fit, the product is considered to be within tolerance. So, when inspecting a cylindrical hole, and the go pin gage does not fit, the hole is too small or undersized. If no-go pin gage enters, the hole is considered too large or oversized. Troubles don't start to appear until the size of the hole is closer to the small side of the tolerance or the large side of the tolerance. This is where the selected measurement diameter, tolerance and measurement force are considered. Commonly used names for Go No Go Gages are: Fixed Limit Gages, Attribute Gages, Hard Gaging and Pass Fail Gaging. No matter what name you use to identify go/no-go gages, you are referring to an inspection tool that is used to check a manufactured part or other material in order to establish if its tolerance falls within the allowable tolerance you have determined as passing. Go and no-go gage dimensions and tolerances are derived based on the product dimensions and tolerances. Most commonly the go plug gage diameter (plus tolerance) would represent the smallest diameter of the product tolerance for the hole. The no-go plug gage (minus tolerance) would represent the maximum diameter of the product tolerance for the hole.