Selecting the appropriate media for vibratory finishing

In mass finishing operations, the type of media chosen plays a key role in the quality achieved. Ceramic, plastic and steel media are available in a variety of shapes, sizes, colours and compositions to help users achieve the desired finish. However, careful consideration must be taken to ensure the appropriate media is selected.

Composition

First consider the composition of the media. This is what determines the grinding performance and surface finish.

Shape

Next, consider the shape. Keep in mind that the media must fit the shape of the component to ensure all contours can be reached and lodging is avoided. The shape of the media also impacts performance, as larger, heavier media cuts more aggressively and leaves a more textured surface.

Size

The difference in size between the component and the media must be sufficient to allow for separation. Media should typically be smaller than the parts so it can pass through a screen if the process involves automatic separation.

The application

Users must keep in mind the type of finish they’d like to achieve, as well as the application of the finished part. Ceramic and plastic media grades are available with no abrasive, which is recommended for very fine burnishing and polishing. However, there are grades that contain silicon carbide abrasive for use on parts that can’t have aluminum oxide impregnation, such as parts that are to be welded, brazed or soldered. Typically, plastic media is most ideal for use with soft metals like brass and aluminium, as well as stringy materials. It provides a smooth but dull finish. Ceramic media is used for fast deburring and tough metal removal, as well as the cutting of hard metals. When media of smaller dimensions are needed, ceramic media is the best option. Stainless steel media is used for burnishing, metal polishing, mirror finishing, tumbling, eliminating manual buffing and pre-plate applications. Steel should be considered when the surface of the part needs to be hardened, as it imparts compressive stress. Steel media should also be used when longer life cycles and greater resistance to wear and corrosion are required.

A trusted manufacturer

Vibratory finishing is one of the many services offered by Mississauga, Ont.-based Vibra Finish. The leading manufacturer and production finishing company has the expertise to help customers select the most appropriate media for the application.

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