Tumble finishing

A well-chosen speed for stone polishing causes the rocks within the barrel to slide past each other, with the abrasive grit between them.

The idea behind the first step is to take rough rock or stone and grind it (tumble it) down into a form which is indistinguishable (in shape) from the final product.

The precise tumbling duration is determined by many factors, including the hardness of the rock and the degree of smoothing desired in the coarser steps.

In burnishing, the rocks are tumbled with only the plastic pellets and the addition of an oil-free non-abrasive soap.

During the 1970s, small rock tumblers were a common hobby item, and jewellery decorated with tumbled semi-precious stones was very much in fashion.

Likewise, dishes and decorative glass jars filled with tumbled stones (often including common rocks not suitable even for costume jewelry) were frequently used as household ornaments.

Metal tumbling is used to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, surface harden, prepare parts for further finishing, and break off die cast runners.

[citation needed] The process is fairly simple: a horizontal barrel is filled with the parts which is then rotated.

[citation needed] As the barrel turns the vanes catch and lift the parts, which eventually slide down or fall.

Common media materials include: sand, granite chips, slag, steel, ceramics, and synthetics.

Tumbling is an economical finishing process because large batches of parts can be run with little or no supervision by the operator.

The parts are usually tumbled against themselves or with steel balls, shot, rounded-end pins, or ballcones to achieve this.

It is also usually a wet process that uses water and a lubricant or cleaning agent, such as soap or cream of tartar.