Finishing Parts Using Vibratory Systems
Mass finishing can be best described as processes in which a number of parts are simultaneously finished. The finishing involves burnishing, deburring, cleaning, removing rust, polishing etc of the parts. The two main types of mass finishing are tumble or barrel finishing and vibratory finishing. In both types, a cyclical action is used to create a grinding action between the various surfaces. Some times, the parts are finished by rubbing against each other. But more often than not, some media is used to achieve finishing. The finishing process can be wet or dry. For a wet finishing, a liquid is used as a cleaner or abrasive. For a dry process plastic, ceramic or dry compounds are used as media. Finishing times vary with the composition of parts. For non ferrous materials, it could be just 10 minutes and for hardened steel, it could take more than 2 hours.
Mass finishing is an art while being a science because the processes involve random action. The mass finishing process could be organized as batch processes, continuous processes or sequential processes. In batch process, a batch of parts are input, worked on and pulled out; the next batch is now input and so on. In a continuous process, the parts are fed and pulled out continuously. In a sequential process, the parts are put through a sequence of processes one after the other. Normally, after every sequence, the part is in a better finished state.
Media are used in mass finishing to accomplish one of four things - cut, luster, parts separation and scrubbing of surfaces. The media could be aluminium media, preformed ceramic media, preformed resin bonded media, preformed shapes in steel, synthetic random shaped media, natural media in random shapes like rocks, cob meal, walnut shells etc. Compounds are used in mass finishing to aid in deburring, cutting, burnishing and so on.
Vibratory finishing machines are used in the vibratory finishing process. The process involves using components like water, finishing media and finishing compounds. Vibratory finishing machines are designed to produce highly smooth surfaces and can act inside deep cavities like tubes. It can be used on varied parts - for delicate parts or large surfaces, which may not be possible in a tumbling process. Loading and unloading vibratory finishing machines is easy. They also have the advantage of lesser cycle times, better cleaning and better color maintenance. These machines are easier to maintain as compared to tumblers. They can mass finish more parts and have less wear on media. Automating or semi automating them is easier compared to tumblers.
Vibrators typically do not have speed control; however, a few of them do. The usual speed is 1700 vibrations per second; for lesser speeds, the parts may sink to the bottom making the finishing process less effective. Vibratory finishing machines work at optimum level when they are between 75% and 90% full. Three parts media to every part metal can be used for delicate parts. For more aggressive finishing, parts can be used without media. http://gravcollc.com/ will provide further details.
