Go/no go

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In engineering and manufacturing, a go/no go (or Go-NoGo) is a process or device used in quality control.

The go/no go process involves any test where the result is pass/fail without giving any information about how close the subject under test came to the pass/fail boundary. Hence they aren't useful in statistical process control, and are traditionally used only to check noncritical parameters where the manufacturing process is believed to be stable and well-controlled, and the tolerances are wide compared to the distribution of the parameter.

For example, the preceding checks before a space shuttle liftoff have the flight controller performing a go/no go check on each of the vehicle's critical systems.

[edit] Go/no go gauges

Main article: Go-NoGo gauge

Go/no go gauges are encountered in all types of manufacturing. They may measure a physical dimension (50 ±.01mm), or a value such as the value of a resistor (100Ω (ohms) ±1%).

A typical gauge used when making tennis balls would have two holes, one slightly larger than the other. A manufactured object passes the go/no go test if it goes through the large hole but does not go through the smaller hole; the object fails if it passes through the smaller hole, or does not pass through the large hole.

Sometimes a go/no go gauge is male and the object being tested is female.