A guide to the Measurement of Roundness

1 Controlling roundness improves performance From power stations to power tools, from the smallest watch to the largest car, all contain round components. In any manufacturing facility it will be seen that machines are producing round or cylindrical components. It is a function of engineering to determine and specify how round they must be; it is a function of metrology to verify if the specification has been met. Roundness contributes to function and performance in many ways, not least of which is maintaining a lubricating film between mating components. Although roundness and size both play a significant role in the way things fit together, roundness is evaluated independent of size and must therefore be measured in a different manner.