Mass finishing is a terminology used to classify the procedure of deburring, cutting, smoothing, polishing, cleaning and separating of parts as a group. This method involves the loading of parts to be finished into finishing machines like the
tumbling barrels, vibratory machines and centrifugal barrel machines. Along with the parts, finishing media and/ or finishing compounds can also be loaded with or without water. Once the finishing machines starts running, the parts graze touching the media at the same time as being suspended in the finishing compounds. The media and compounds have rough properties which cause the surplus metal (or any other material with which the parts are made) to be abraded away.
The process of mass finishing might use tumbling machines that are barrels which are made to rotate or vibratory machines which are tubs that vibrate at very high speeds with short strokes. The finishing media used could be natural media like the corn cob media and walnut shell media or artificial media like plastic
deburring media and ceramic media. While natural media provide soft abrasive action on the parts, the artificial media are used for medium to heavy deburring. Plastic media being lighter compared to ceramic media are used with delicate and fragile parts while the ceramic media is used with heavy loads that need cutting. They come in all sorts of shapes to handle different sizes and patterns in the parts being finished like conical, pyramidal, cylindrical, triangular and so on.
Finishing compounds are used in the mass finishing process to increase media efficiency. They give additional abrasive property and more cutting power. They prevent glaze formation in the loads so that the media can work better on the parts. These compounds can have alkaline or acidic properties and come in the liquid, powdered or cream forms. When cleaning of parts is desirable during the mass finishing, compounds come in very useful. They are good cleaning agents that can degrease, de-scale and de-oxidize. They can also be used to impart properties like anti-rust and anti-corrosion in the parts by using certain chemicals in particular for this purpose.
Centrifugal barrel machines are finishing equipment used in finishing of parts. They typically have one or more barrels mounted on turrets. These barrels are made to rotate at very high speeds so that the principle of centrifugal force comes into play inside the barrels. The load inside the barrels is thrown to the walls of the barrel because of the centrifugal force that acts on them at the barrel center. The parts and media that have been put together thus rub with each other continuously at a very high rate of speed producing the desired deburring and cutting action.
The centrifugal barrel machines take less time to finish parts as compared to standard barrels or vibratory machines. They have protection latches to keep the loads securely inside when turning. They are simple to load and unload. Centrifugal barrel machines come in different capacities, different horse power for motors, electrical powers and delivery weights to suit different finishing operations.
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