Unstable vibration in centreless grinding: Part 1. Geometric instability or chatter?

Centreless grinding is widely used as a production process for removing initial roundness errors from workpieces. The process can be prone to vibration and the causes of this have been investigated and reported in many publications. This paper describes a model of centreless grinding that includes the machine dynamics, regeneration on both the workpiece and grinding wheel and allows unstable vibration to be investigated. It further allows the division between geometric instability and chatter to be shown to be unnecessary and artificial. A frequency domain model is developed that allows growth and decay rates to be determined. The main aim was to examine possible solutions for unstable vibration in centreless grinding. As flexible grinding wheels have been used to prevent chatter in other grinding processes, their use for centreless grinding was investigated and is shown to be ineffective.