Metal Finishing Guide Book


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Component Function Mass finishing machine (1) Induces the energy to put the parts/media mass into motion and (2) Creates a "rubbing" action between parts and media Water (1) Serves as a coolant for the process (2) Absorbs potential dust (3) Dissolves and distributes the compound in the work bowl Compound (1) Dissolves dirt and grease from the parts surface (2) Cleans the media to keep its "grip" on the part surface (3) Together with the water flushes media- and metal-fines from the work bowl Media (1) Generates the desired surface finish���deburring, radiusing, smoothing, polishing, etc.���by constantly "rubbing" on the part surface (2) "Cushions" the parts from each other, thus avoiding impingement Table 1: Selecting the Proper Components to Optimize Finishing Operations ly sophisticated product line consisting of different materials, geometric shapes, and sizes (Figs. 8 and 9). Today there are a huge variety of media that a user can choose from. And if mass finishing has an ���artistic��� element, it lies in the selection of the right media with regard to type, shape, and size. Only with the right media choice can the desired surface finish be achieved. Many times the media selection process requires comprehensive and time-consuming processing trials. But the payback for such efforts generally is substantial in the form of optimum and cost-effective finishing results. Figure 10 shows a partial view of a present-day test laboratory. Main Types of Mass Finishing Media Mass finishing media are generally classified into the following categories: ��� Ceramic (including porcelain polishing media) ��� Plastic (mainly polyester-based, but also including urea/formaldehyde media) ��� Steel media (in hardened carbon steel and stainless steel) ��� Organic media (for example, granules made from corn cob and walnut shells) ��� Other media (for example, glass beads, polyamide micro-beads, etc.), which play only a minor role in vibratory finishing and are not discussed further The most commonly used mass finishing media are either ceramic- or plasticbased. They account for approximately 80���90% of all media used in mass finishing applications. All other media are specialties that are used for certain applications, Ceramic and plastic media always have one common characteristic: They consist of a carrier that is mixed with certain types of abrasives! 14

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