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Correct fill level loading is one of the fundamental operating parameters. The ideal fill level is approximately 50 percent this permits for the longest possible slide zone. Most abrading or polishing o parts occurs within the top 10 -20% of the media load, and maximizing the length of the slide zone is key to shorter cycle times
Examples of tumbling equipment is shown below.
Shown above is an example of an octagonal horizontal rotary barrel. This style of equipment has been in use in North America and Europe since the early part of the twentieth century for bulk-processing large numbers of metal parts that required deburring, edge-break, radiusing, smoothing, burnishing and polishing. This style of equipment was widely used for abrasive finishing metals in various abrasive media along with water and compounds. Dry processing with finer polishing abrasives and natural materials were used to produce fine finishes on plastics and many non-ferrous metals with surfaces that rivaled that of traditional buffing and polishing operations. This kind of finishing is still commonplace in some industries that require high-quality decorative finishes in both North America and throughout Europe.
Tumbling barrels are available in a variety of configurations, the most common being a horizontally oriented octagonal chamber, which provides a much more efficient media lift than a purely cylindrical shape. Other configurations include barrel chambers mounted on pedestals, barrels with front or end loading, perforated barrels encased in a water tank or tub, and so called triple-action polygonal barrels. Also used extensively are oblique barrels, similar in some respects to small batch concrete mixers. This equipment is used for light deburring and finishing as well as part drying. It has the advantage of permitting operator inspection while in process, and its open end can be tilted down for ease of unloading, but it is much less efficient than horizontal equipment, and suffers from the tendency of parts and media to segregate in extended time cycles.
As is the case with most other mass finishing equipment, polyurethane, rubber, or linings made from similar material are used to extend equipment life, provide some measure of cushioning to parts, and furnish some measure of noise abatement. Although considered by some to be an outdated and obsolete finishing method, barrels still have a place in the finishing engineer’s repertoire. Although it is true that it is slower and presents some automation and materials handling challenges, it is sufficiently versatile to perform numerous finishing operations for many manufacturers. Furthermore, barrel finishing provides an excellent alternative for flat parts, which may nest in vibratory systems. Although perhaps requiring some measure of operator experience in order to be used effectively, barrel finishing is capable of producing some unique and desirable surface finishes and is highly efficient in compound and media usage.