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Mould inserts with high form accuracy can be produced with ease using modern grinding technologies. However, several grinding cycles are often required to reduce the form error to an acceptable value, significantly dependent on the tool path compensation technique used. This paper reports on a novel form error compensation technique for tungsten carbide mould insert machining utilizing a parallel grinding method. In this technique, a newly developed program is used to process the profile data measured using a Form Talysurf profilometer, and to further generate the NC tool path for form error compensation. The developed technique focuses on the compensation of form error resulted by two major error sources, wheel radius and waviness errors. Using the developed technique, the initial residual form error upon the completion of primary grinding is minimized. Subsequently, the residual form error is compensated by modifying the NC tool path. With this technique, the speed of convergence of the residual form error has improved markedly. The grinding result shows that, after just one compensation cycle, a form error of approximately 0.3 µm in PV is achieved.

Ultraprecision grinding and polishing are used to machine end faces of fibre optic connectors. The grinding produced spherical end faces with an average R a value of 6.9 nm in the fibre area and a form error of approximately 0.2 µm, corresponding to a return loss of 55 dB and an insertion loss of 0.1 dB. The optimized polishing process also produced a satisfactory result with high efficiency. The comparison between grinding and polishing has demonstrated that fibre optic connectors machined by both methods can achieve the required optic performance. The grinding certainly produces a better and more consistent quality than the polishing but with a lower efficiency.