Mass finishing media is used to debur, burnish, color, descale, polish or clean parts and components during finishing processes. Mass finishing media involve choosing finishing shapes and media for particular tasks. Finishing shapes include balls, cones, ballcones, wedges, pins, tapers, cylinders, cut wire, diagonals, angle cuts, diamonds, cubes, oval balls, eclipses or balls with flats, crushed grit, pyramids, triangles, and stars or tristars. Finishing media consists of metal, ceramic, plastic, natural, wood, nutshell, corncob, carbonate, mineral, and synthetic materials.
Selection of mass finishing media includes matching media shapes and material to the component material, component geometry and finishing process. For example, softer materials such as plastic or non-ferrous metals require less aggressive media. If a chemically active, corrosive or acidic compound is used, then a corrosive-resistant media material should be selected. In situations where complex parts with recesses, corners or holes need to be finished, pointed media such as cones, triangles, pins, and ballcones should be used. Mass finishing media are used in a variety of barrel finishing systems, from a light-duty miniature tumbler to a large heavy duty multiple-compartment machine designed for wet or dry processes.
Mass finishing media for part deburring and burnishing is typically ceramic preformed shapes. Ceramic shapes are best for hard metals and are able to debur metals better than plastic shapes. Mass finishing media for descaling, polishing, and cleaning includes components made a variety of materials: carbon steel is used to produce a bright shine, stainless steel is used for aggressive processes such as removal of iron contamination, and precision ceramic forms are used for fine finishing jobs such as jewelry polishing. Synthetic mass finishing media is used in high-pressure, high-energy processes, such as those used in a centrifugal barrel or disc finisher.