Grinding and polishing tools - joke Technology GmbH - #5

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92 2 i Tel. +49 (0) 22 04 / 8 39-0 • Fax +49 (0) 22 04 / 8 39-61 • info@joke.de 2. Grinding and polishing tools Grinding and polishing tools Basic principles Finest working processes in tool and mould making The border between grinding and polishing is not clear-cut and a clear distinction often difficult. Generally, three processes for the fine processing of surfaces can be identified: polishing, polishing and lapping and lapping, all of which are chipping processes with loose grit. These achieve the best roughness values (see page 84). The surface quality achieved with these processes is mainly dependent on the following factors: • Grit size of the abrasive • Working pressure • Work movement • Grading of the various abrasives • Choice of lapping and polishing agent carrier Grinding In the preliminary processing, these finest working processes (finishing) are often preceded by (manual) grinding. Grinding is a chipping process with fixed grain. See right for an overview of typical abrasives. Overview of work processes in tool and mould making Definition Process Result Manual grinding Chipping process with fixed grain Directional movement, material is chipped by fixed grain Directional surface Polishing Chipping process with loose grain Directional or undirectional, grain “embedded” in polishing cloth or felt High-gloss surface Lapping Undirectional crossing movement, rolling grain Matt surface Lapping and polishing Directional or undirectional movement, grain penetrates carrier Shiny surface Basic principles that should be adhered to: • Always from coarse to fine • Clean workpiece thoroughly after every grit change • Change lapping or polishing media when changing grit Tool Workpiece Lapping compound Lapping Carrier Workpiece Lapping compound Lapping and polishing / polishing