Preformed tumbling media used in both vibratory and barrel tumblers are simply the means to achieving a desired surface finish. The type of media formulation or BOND used can vary widely for each process or application.
Tumbling media is a blend of abrasives and binders. Ceramic Media is generally a clay or porcelain binder while Plastic Media and Synthetic Media are typically made from urea formaldehyde or polyester polymers. These binders are used to hold (bond) and shape the abrasive grit blend needed for a particular media type. Aluminum oxide and silicon carbide are the most popular abrasives used.
The specific type of binder and abrasive used along with the ratio of binder to abrasive will determine the impact of the media on the part. A high abrasive content will lead to quicker break down of the media and a more aggressive operation. Low or no abrasive content will result in a media that is very soft/gentle on the part and used for polishing and fine finishing.
All tumbling media are designed to break down or erode during use. This is necessary to perform the ‘work’ on the part. Generally, the quicker a media breaks down, the more aggressive the bond. The ideal media for any process will provide the minimum erosion (longest lifetime) but must be balanced with a reasonable cycle time to achieve the desired surface finish.