May 2012 Archives

Planetary rotation barrel polishing is a polishing method of using a turning radius several times that of the rotating barrel and 180~250rpm speed, where the polished objects are centrifugally pushed towards the inner wall of the barrel at its circumferential limits.

[Fig.1] shows the flow of the polished parts within the barrel.

The polished parts and the abrasives are friction polished by the effects of centrifugal force and many specific characteristics can be seen. For instance, the polishing amount increases rapidly in proportion to the processing time duration, several multiple of ten times that of standard barrel polishing.

Also, ultra small parts and thin plate parts can be polished, as well as mirror surface finishing of soft metals became possible.

With this polishing method, soft aluminum parts became possible to be precision polished. Also, pressed parts and die-cast precision gears are polished this way, especially for ornamental gloss surface finishing this is replacing buff polishing. [Fig.2] shows an external appearance of a planetary rotation barrel polishing machine.

Some polishing stone (abrasive) types, principle components, and applications are shown in [Table 1] below.

[Table 1] Polishing stone types and applications

Vibrating barrel polishing is a method of applying zigzag motion and high cyclic vibrations on barrel contained parts and polishing agents.

There are box type and circle type of vibrating barrels. The former performs one dimensional motion whereas the latter performs three dimensional motion.

The vibrating barrel, similar to the rotary barrel counterpart, also uses the parts and abrasives together in the barrel to polish.

The [Fig.1] shows the flow of the barrel contents, and [Fig.2] shows external appearances of the machines.

In general, 7~5mm at 1,800~2,400cpm vibrations for heavy cutting. For gloss finish polishing, the vibration speed in increased to 2,000~2,800cpm while the amplitude is decreased to 5~3mm.

The most important point for barrel polishing is the selection of the abrasives, as it is common for a various barrel polishing types.
As polishing abrasives, there are various shapes and sizes of ceramic materials commercially available.
The shapes and sizes are selected from: diamond shape, triangle, oval, spherical, and granular depending on the polishing subject.
Compounds are added for grinding, polishing, or gloss finishing purposes, and act as agents to lubricate, de-scale, and to prevent from rusting. Some alkali salts such as 0.5~0.8% of sodium stearate soap and sodium phosphate are also used.
When the polishing is finished, the parts and abrasives are separated by magnetic separation if ferrous, or by sieving otherwise.