30 + - Coating techniques The orientation of the grains is decisive for the surface quality of the workpiece. VSM uses two different coating techniques to properly orientate the grains: electrostatic coating and mechanical coating. The electrostatic coating process is a method where the grains are not scattered onto a substrate. They move upwards and accelerate towards the substrate while travelling through an electrostatic field. During this process the grains are oriented to achieve an upright position, in which they are bonded to the substrate. VSM has its own facilities to integrate this process in-house. The result is a product with maximum sharpness. General · VSM grinding technology Types of coating Different types of coating are used in order to benefit as much as possible from the grain properties and the space between the grains for chip removal. VSM uses standard, combination and open types of coating. In a Standard coating the grain is bonded to the maker coat with the grain in an upright position. The gap between the grains may be narrow (closed coating density) or medium (coating density medium closed). When applying a Combi coating supporting grains are placed in the gaps between the grains in order to retain the grain in position. This type of coating works best for applications where a machine limits the contact pressure. In an Open coating the grain is again in an upright position on the backing. However, the spacing between the abrasive grains is much bigger. The pressure spreads onto fewer grains so that the individual grain has to absorb much more of it. This in turn enhances the self-sharpening effect (page 29) and improves the chip removal. The principle of electro static coating electrode electrode substrate abrasive grain conveyor electrostatic field Standard coating, closed-coated Standard coating, medium closed-coated Combi coating Open coating
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