Electrostatic tool wear in diamond turning of amorphous polymers

An increasing amount of products is made from polymeric materials. Examples are contact lenses, spectacle lenses, intra-ocular lenses and drums for copiers. Also in prototyping polymeric materials are more and more used, e.g. lenses for DVD/CD players. For higher flexibility and higher accuracies, these products are being precision turned with diamond tools. Since diamond is the hardest material in the world and polymers are relatively soft only little tool wear is expected, but the opposite is the case. Some industrial laboratories claim that electrostatic discharging between tool and workpiece causes diamond tool wear. This may be true, as both diamond and polymer are electrical insulators. During cutting friction appears and this would cause electrostatic charging. This paper presents some results of the influence of electrostatic charging in the precision turning process of polymers on diamond tool wear.