Choosing Tumbling Media For Vibratory Deburring Machines

A common deburring machine used for mass finishing parts is a vibratory deburring machine, or vibratory tumbler, which utilizes abrasive media to deburr, clean or polish unfinished or dirty parts or objects. The abrasive media and unfinished or dirty parts are put inside a large drum. The drum vibrates, driving down the contents in a circular motion, mixing everything together. The unfinished or dirty parts are subsequently deburred, cleaned or polished by friction with the abrasive material.

The type of deburring, cleaning, or polishing desired and the part characteristics will determine the type, shape, and size of the abrasive media used. Some common types of tumbling media are abrasive steel, plastic, ceramic, and organic materials. These materials can be purchased in a variety of shapes, such as stars, pyramids, cones, wedges, spheres, cylinders, ovals, and other forms depending on the function needed. Holes or slots in the parts will determine the size and shape of the media used. To prevent media lodging in the part, it should be a minimum of 70% the size of the hole or slot. This avoids two pieces getting stuck side by side in the piece.

Here are some common uses for abrasive media:

Steel media– Use for heavy deburring, or shining, polishing and burnishing metal, plastic or ceramic parts. Since plastics have a high abrasion resistance resulting in a matte finish after deburring, a second, polishing step is often required.

Ceramic or graded stone media– Use for light and heavy deburring, and when fast deburring is needed. Good for hard, heavy metals (such as steel or stainless) and to remove rust on parts. Use for general purpose polishing. Plastic, steel, stainless, and aluminum parts are often polished using ceramic media. Use ball shapes to polish aluminum to avoid nicks.

Plastic media– Use for general metal deburring, precision deburring, polishing and burnishing. Use on softer metals such as aluminum or brass and on threaded parts.

Organic media (walnut shells, coconut shells, corn cobs)- Use walnut shells and coconut shells for medium to light deburring. For light finishing and polishing, use walnut shells, coconut shells and corn cob meal. To clean and dry wet or dirty parts, use organic media. Corn cob is particularly desirable in finishing some metal parts because of its ability to absorb surface oils on the parts. Utilizing organic media is advantageous because they are natural, safer for the environment, biodegradable, durable and reusable.

Wet tumbling compounds- Used by mixing with solid media to deburr, finish and polish parts, their function is to clean, enhance deburring, and for corrosion and rust protection.

Abrasive media for deburring equipment wears down slowly, but will vary on how aggressive the media is. Also, the smaller the media, the better the finish, but the longer it will take. The larger the media, the faster it will deburr. Having the correct media and the deburring machine full of parts is the key to successful finishing.