Finishing is the process of altering the appearance or properties of the surface of a manufactured item. Finishing media, simply known as media, are used in the finishing operation. Media comes in various shapes and sizes; they are made from different materials – depending on what they are going to be used for. Plastic media, ceramic media, organic media and chemical media like liquids, gels and powders are some of the most popularly used ones.
Finishing process can be used to: enhance appearance, improve polish or impart properties like adhesiveness, corrosion/ tarnish/ chemical resistance, wear & tear resistance, hardness and so on. How is the finishing process carried out? It is done by using tumbling and vibratory machines. The components are loaded into these special machines along with the finishing media; the items to be finished and the media are allowed to tumble and/or vibrate together. When this happens, they grate against each other and this causes an abrasive action to take place on the surface of the items that need to be finished – cleaned, deburred or polished. After this is carried out for a specific period, the components come out with the desired finish.
Plastic polishing media is a gentle abrasive and is best suited for applications where a soft polishing effect is required. This media has a very low density and is light in weight compared to ceramic media. Hence there is no risk of parts being damaged during the finishing operation. It is found to work best on fragile parts made of aluminium, composites, fibreglass etc and is used widely in the maintenance of airframe components. It is also used effectively in the electronic components’ deburring and deflashing. “Cleaning” components – removing paint, dust, grease – is another area where this media is frequently applied. It comes in shapes like cones, pyramids, and irregular shapes and so on. Various plastic types are used to make the media in different hardness levels depending on their ultimate purpose. It is considered to be fast, cost effective and more environment-friendly when compared to chemical usage and hand stripping.
It is very important to use the correct finishing equipment along with good quality media having the right composition. This is the best way to ensure that the finishing process achieves the exact, desired effect. Media plays a critical role in determining the time needed for treatment, productivity and also the overall cost in finishing a part.
Mechanical finishing is the process that is carried out before a chemical finishing or anodizing process. This finishing style is used to impart a specific surface texture; it is also effective in removing any defects and/ or irregularities on the surface of an item. The end finish from this process typically has a matte look or a sanded look or a mirror like finish. A mechanical finish is achieved on metals by using abrasive media.
This finishing process includes:
• Abrasive blasting like sandblasting
• Burnishing
• Grinding
• Mass finishing like tumble and vibratory finishing
• Polishing like buffing
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