Finishing is a term to describe the process of burnishing, cleaning, deburring and separation of parts using machines and materials called media to assist in the process. It is an important process to ensure that the parts come out with high quality in terms of a smooth fit and proper functionality apart from becoming aesthetically sound. There are primarily two types of machines used in mass finishing of parts – that is finishing of several parts together. These are tumbling or barrelling machines and vibratory machines.
Tumbling barrels are typically used for rough and tough jobs on hard metals. They are very good for deburring of heavy burrs. They are also recommended for burnishing, radius-ing of jagged edges plus breaking parts from runners. They can unction with or without using finishing media. Tumbling barrels are ideal when the loads are heavy; such loads cannot go on vibratory systems. These barrels run at optimum level when they are half filled. Barrels that have screens can be used as a plastic deflashing machine. Parts can be separated when screen doors are installed in these barrels.
There are wet and dry tumbling barrels. Wet barrel involves batch processing which means the parts are processed as batches. They are used for deburring and polishing, radius-ing, cleaning and improving the surface appearance and smoothness. Processing metals is best done in wet tumbling barrels. This equipment can be used in dry processing too, when needed. Dry barrelling is also a batch processor which is normally used to polish and deburr without liquids. Dry barrels can deflash, grind and form radii too. Compared to a wet system, these produce smoother and more uniform finish. Predominantly, wet tumbling is used in tumbling barrels. But specific cases like lack of readily available water make the dry process a more viable option.
Centrifugal barrel machines are also used in mass finishing of parts. They have gained a lot of popularity because they are the fastest finishing machines available today – about 20 times faster than a vibratory sytem’s cycle times. They are high energy machines in which the parts are placed in closed barrels. Finishing media, water and finishing compounds are added on. The barrels rotate to provide a sliding action inside which gives a uniform finish to the parts. The barrels are made of steel or a composite material and have urethane lining. They can be removed for loading and unloading purposes. Composite barrels can be used where cycle times are expected to be under an hour. For longer durations and larger machine, steel barrels are advisable.
The centrifugal barrel machines come with electronic controls that make them very simple to use. These controls include a process timer that controls the rotation times. There is an emergency stop for crisis situations. Indicator lights help in process tracking. Safety features are there to ensure that these machines cant run without covers and other locks in place. They are also typically wired for different voltage needs.
By: Mark West
About the Author:
Grav Co LLC continues to manufacture the finest mass finishing equipment and supplies in the marketplace. We still build centrifugal barrel machines, vibratory finishing, disc finishing, tumbling barrels, and spin finishing equipment in our Sturgis, Michigan plants. We also manufacture vibratory finishing media, treated cob meal and various liquid and powder compounds, and have a very good line of ceramic finishing media.
