Tumbling Media Selection Guide

The following guide will help to give basic tumbling media information on ceramic media, plastic media and hardwood media selection.

Which stone size to use is determined by the ability to separate the stone from the part, holes the stone could jam and the ability of the stone to get at the desired surface. Large stones give a rapid cut, but coarser surface and more rounding of edges. Small stones give a slower cut, smaller edge break and a finer surface.

Ceramic Media Selection Guide

Ceramic media is best for heavy cutting and hard metals. Ceramic media will better support very heavy parts than plastic media. Fine threads or a hanging burr can be peened over by ceramic media, whereas plastic media won't peen. When a small media is required, ceramic media offer the best selection.

Plastic Media Selection Guide

Plastic media is used for soft metals (brass and aluminum) or stringy materials to produce a better surface finish and to avoid rolling the burr over into a hole. Plastic media will produce a very smooth finish, but very little shine. Plastic media is good to use when preparing parts for anodizing. Tetrahedrons or cones are good for parts with holes. Triangles are good for corners and flats. Plastic media gives the best surface quality. It does not discolor metal and does not peen over burrs. Plastic media is 30% lighter than ceramic media.

Hardwood Media Selection Guide

When using hardwood media, using larger wood pegs in the cutting step can speed up the operation. Smaller wood pegs are better for polishing. However, consider using the same size wood pegs for all of your jobs, since the dirty pegs from polishing cream barrels can be reused in a cutting step. Dirty wood pegs can be cleaned during dry cutting operations when run with Shynolyte Pre-Polishing Cream or by running with mineral spirits and corn cob grit.

Consider the following factors when selecting tumbling media:

1. What shape and size is required to reach the burr?
   1. Use sizes that will not lodge in holes or recesses and shapes that have the ability to get at all surfaces.
   2. If using small tumbling media, does it have to be helped by mixing with a large tumbling media to push it and/or help it cut faster? Tumbling Media is usually mixed at two parts small stone to one part large stone.
   3. Which tumbling media size to use is determined by:
      1. The ability to separate the tumbling media from the part.
      2. Holes the stone could jam.
      3. The ability of the stone to get at the desired surface.
2. Which bond?
   1. How bad is the burr? What is the required surface of the finished part?
      1. Large tumbling media will give a rapid cut, but a coarser surface and more rounding of edges. Use large media for rapid burr removal if finish is not important.
      2. Small tumbling media provide a slower cut, a smaller edge break and a finer surface. Use small and well-worn tumbling media where a high finish is required.
   2. How aggressive does the media need to be?
      1. Fine cut vs. coarse cut.
      2. Use small tumbling media on fragile parts. Large tumbling media may bend or damage fragile parts.
   3. Are the parts ferrous or non-ferrous?
3. Can the tumbling media chosen be separated out from the part? If not, go back to step 1.
   1. Choose a size that can be screened or separated from the parts.
   2. Screen tumbling media often to keep sizing uniform.
   3. Consider wear of the tumbling media when checking for hole-jamming potential.