Vibratory finishing is one process that can be used to smooth objects by placing them into a vibrating device along with pellets of an appropriate material. The vibrating action of the device causes the finishing material to work against the workpieces and can cause a deburring, descaling, or brightening effect depending on the medium used. Finishing media can include both natural and synthetic products, and is also classified by shape and degree of uniformity. Unlike regular tumble finishing, the vibrating motion of this process can allow the abrasive media to act on interior portions of workpieces rather than just the exterior.
Batch manufacturing often uses vibratory finishing to clean up a large number of workpieces at once. After the workpieces have been cast or otherwise produced, they are typically moved in batch form to a vibratory finishing station. At this point, the workpieces can be placed into a vibratory drum along with an abrasive medium. Each type of medium has its own unique qualities, so different materials, shapes, and sizes are chosen to achieve particular effects. It is also common to place additional compounds into the vibratory finishing device to assist in cleaning, deburring, or burnishing.
The media used in vibratory finishing are typically designed to cut, polish, or scrub. Cutting media are usually fairly abrasive and designed to physically slice or shave burrs and other imperfections from the workpieces. These materials will usually result in a dull or matte type surface finish on the product. If a luster is desired, media that are either lightly abrasive or entirely nonabrasive may be used to achieve a peening effect, which involves striking the surface of a workpiece without abrading any material. Scrubbing media can be either abrasive or nonabrasive and are usually meant to clean off dirt and other contaminants.
In addition to performing various cleaning and deburring tasks, the media used in vibratory finishing can also serve the purpose of separating workpieces. If very low amounts of tumbling media are used, the chance for workpieces to contact each other during the vibratory finishing process can be high. This is often undesired because if workpieces vibrate against each other there may be damage to the products. The ratio between the medium and the workpieces is typically used to control this type of contact.
Media used during vibratory finishing can vary from natural products, such as walnut shells, to synthetic plastics. Each material has unique properties that can be best suited to cutting, polishing, or scrubbing. The shape of the medium can also be important, and balls, ovoids, wedges, and various other configurations may be used.