Media Shape
Normally, you select the shape and size of media for two reasons. One, to deburr parts with rough outer surface features, and two, to deburr parts with both internal and external surfaces.

For reason one, you don't have much of a problem because you are talking about parts that basically have two dimensions and little depth. In this case, use the biggest media possible. The triangle or tristar is usually the preferred shape because of its ability to penetrate without getting stuck and its large surface area and / or leading edge. This flat shape requires more energy to move and creates higher resistant forces that will remove more material in a shorter amount of time.

For reason two, deburring both ID and OD, the cylinder shape lens itself to most applications. It offers greater mobility than a flat configuration and can pass more easily through holes and recesses. If you want to deburr inside holes, select a cylinder just under the size of the smallest hole, but more than half its OD. This will keep two or more pieces from jamming up inside. Most cylinders come in three different angle cuts. The standard angle cut is 22. There is also the 45 and the 60. The angle cutis what works most Ids. Because of these angles, you may not need to select an under-sized cylinder, but may work the area from outside or above the hole.

Unfortunately, there is no one size or shape media that can do everything. The closest thing to this is a shape called the wedge tricylinder or the 'V' cut cylinder. This shape excels in its ability to penetrate and its extreme mobility. All media's are geometric in shape and this usually means that center of gravity is located at the center of each media piece. However, center of gravity falls on the outside edge of the 'V' cut shape, making it very unstable and/or mobile. For this reason, it is the best general or universal shape to use when in doubt.


Media composition
There are many grades of media, but normally there are five in standard ceramic and at least three in plastic.

The coarsest or fast cut also breaks down the fastest. When referring to coarse media, we are talking about the grain size of the largest material in suspension of the matrix compound. This is usually aluminum oxide, but can also be silicon carbide, silicon, quartz, garnet, or other material. Supposedly, the fastest-cutting and more expensive type is silicon carbide. The least expensive is aluminum oxide. Plastics are generally a little more in cost than ceramic, and steel media's are the most expensive at two to four times the cost of ceramic. Wood media is relatively inexpensive, especially if you take volume into consideration.

The normal time cycle in vibratory equipment for coarse media is usually less than 30 minutes, unless there are big surface variations or the media is hardened. At the media grain size becomes smaller or finer, the time cycle increases and RMS improves. When you reach the finest ceramic media which is porcelain, you are no longer removing material or deburring the part, but actually rolling or lapping the part. Any breakdown or material removal is the result of bending and flexing, and fatigue of the burr. Time cycles of one hour or more are standard. Unlike coarse media's that work better new, porcelain becomes more efficient as it gets older.

Plastic or synthetic media's generally take much more time to work than does ceramic. However, they are usually better on non-ferrous brass, aluminum, zinc, etc. This is die to lighter specific gravity resulting in reduced material removal for a finer and lower RMS. Time cycles can very from 30 minutes to an hour or greater.

Steel and wood media's do not normally have grades or different compositions. Size and compounds play more a part in the material finishing than does the grit.