Normally using a CAD file as a starting point, the machining centre is fed a series of instructions, specifying direction and depth of cut, cutter speeds, and every other feature necessary to turn our raw material into the finished part.

Once the programme for the file is tested and approved, it can be run time and time again with exceptional repeatability and at high speed.

But what about inspection? In a scenario where a client requires inspection of every part produced there’s little point in producing components at breakneck speed only to create a logjam within inspection, where skilled inspectors check dimensions with micrometers, verniers and height gauges.

This is where a CMM comes into its own.

A CMM, or Co-ordinate Measuring Machine can look, in it’s most common form, pretty much like a version of the CNC equipment used to produce the components its designed to measure.

But instead of finding a cutter at the business end of the machine we’ll find an extremely accurate probe.

So once again using the very CAD programme which defined the shape of our component in the first place, we can use those co-ordinates in X, Y and Z to define exactly where in space any feature of the component is supposed to be.

By piloting the probe, robot fashion, we actually make contact with any given feature, say a horizontal surface, and report precisely where in space it is located.

Then it’s a matter of comparing this data with the original manufacturing information and establishing if, in fact, the given feature is occupying the same point in space as the CAD file says it should.

A CMM is an expensive indulgence but is capable of inspection at speeds hundred of times faster than even a skilled inspector and as such is invaluable when speedy, accurate inspection is a must.