Tumbling-Media

Mass Finishing Renders High Quality Parts

Parts that are manufactured usually need removing of jagged edges, cleaning and polishing before they are fit to satisfy their functionality (the function for which they are being built). This is achieved by means of a process called finishing. Mass finishing is several parts being finished all together. It is typically carried out in finishing machines or systems like tumbling machines, vibratory machines, blasters, centrifugal machines etc. Parts are fed into these machines along with finishing media, finishing compounds and water. The parts and the finishing media scrub against each other, with the compounds aiding in removing the debris and keeping it from re-depositing on the parts. Due to this scrubbing action, mass finishing takes place - edges are smoothed, surfaces get polished, nooks get cleaned and parts get broken from runners.

Finishing media are materials that aid in the mass finishing process. There are many types of media like synthetic pre formed plastic media, ceramic media and natural media like corn cob and walnut shell media. Finishing compounds could be dry or wet and depending on the action required, their composition varies. This determines their abrasive action, alkalinity etc. Mass finishing process can take place as a batch process, as a series of steps or as continuous process. In a batch process, parts are loaded as a batch and after finishing, the batch is unloaded. The next batch now goes in and so on. In the step by step process, the parts are taken through a sequence of processes, one by one. After every step, the parts will have some degree of finishing done on them and after the final step, they will be fully ready. In a continuous process, the loading and unloading of parts happens continuously, while the finishing process is carried out.

Walnut shell media are made from treated and crushed walnuts. As they are natural, they are bio degradable and safe for the environment. They are dry finishing media whose grain size is determined by the weight and composition of the parts being finished. They are very good cleaners too apart from being good polishers. They are suited for use with tumble machines and useful in finishing of parts made from soft metals like brass, aluminium and bronze. Mixed with paints, they act as anti skid agents and are typically used in paints used around swimming pools and pathways. Oil well drilling is another area where they are used, to prevent the oil from stagnating.

Walnut shells have the properties of hardness and fibre. They are also naturally angular and multi faceted, which makes the walnut shell media ideal for deburring. They last long and can be reused many times over. Used in tumbling and in some vibrating systems, they help to reduce cycle times. They can be used on delicate surfaces because they do not have a rough abrasive action. So, they do not damage micro finishes. There are companies who have been in the finishing business for a long time; they can find finishing solutions for any needs. To learn more visit http://gravcollc.com/

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.