Polishing dynamics - How to optimize the parameters during grinding and polishing in materialographic specimen preparation

The polishing dynamics play an important role at materialographic grinding and polishing. The dynamic conditions at a typical materialographic equipme nt set-up is examined, based on the speed and rotational direction of the g rinding/polishing disc and specimen holder. This is done mathematically and through experiments. It is shown that the optimal polishing conditions are when the disc and the specimen holder are rotating with the same speed in the same direction. Vectors indicating the speed at a given point of the sa mple surface are shown. At polishing comet tails and other artifacts can be developed at not optimal polishing dynamics. At grinding it can be an adva ntage to increase the speed of the disc to heighten the removal rate. Theor etically the disc and the specimen holder shall rotate with the same rpm, b ut it is shown that a small difference is necessary to avoid excessive wear of the disc surface.