The tumbling process

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March 10, 2021 / By Pai Cristal Italia

The tumbling process

What is the tumbling process?

The tumbling process is used on an industrial scale for the removal of surface flaws caused by previous working processes and for the following polishing of the different materials surfaces. The tumbling and the vibrofinishing processes are normally used for the polishing of plastic, metal alloys, precious metals and natural materials too.

What’s the tumbling – vibrofinishing process for?

The tumbling is a process formed by 4 different steps: grinding, smoothing, polishing and shining.

The purpose of the tumbling process is obtaining a shiny and “flat” surface without flaws.

  • The grinding is the first step of the process, where the most accentuated flaws are removed.
  • The smoothing is the second step of the tumbling process, where smaller flaws and the residuals of grinding process are removed.
  • The polishingis the third step of the tumbling process.
  • The shining is the last step of this specific process: it is the final phase, the piece to be treated will be brilliant and the surface will be shiny as a mirror – without any surface flaws.

Thanks to more of 50 years of experience, we have managed to develop abrasive pastes, compounds and processes for every phase of the tumbling process. According to the kind of treatment, Pai Cristal can supply abrasive pastes and compounds that reduce the phases of the tumbling process, joining, for example, two steps of the process: smoothing-polishing together can reduce by far the time of working and tumbling.

Descover the abrasive compounds Pai Cristal for tumbling of acetate and injected plastic. It’a a complete cycle starting from grinding to shining.

What materials can be tumbled?

A large quantity of materials can be tumbled:

  • Plastic materials especially cellulose acetate, polyamides, polyesters and polymethylmethacrylate
  • Metal alloys
  • Precious metals
  • Natural materials like horn, mother-of-pearl, corozo, wood

The tumbling or finishing process with tumbler is used in different sectors, particularly eyewearsbuttonsjewelry, and in the surface treatment of small metal parts too and more generally of fashion accessories (for example costume jewelry, accessories for hair).

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Legnetti per buratto per la lucidatura/burattatura di occhiali in acetato di cellulosa

Difference between dry tumbling and wet tumbling

The tumbling process is divided in two big types: dry tumbling and wet tumbling

Wood media (beech or birch) and plastic media in different shapes and dimensions, or vegetal walnut or corncob granules are normally used in “dry tumbling” and the abrasive pastes are added in.

In “wet” vibrotumblers (with water), used for grinding of metal, polyester, ceramic and porcelain media are used. They emit themselves some abrasive elements which specific pastes and detergents are added to.

What is a tumbler?

The tumbler is the machine which the tumbling process is realized with. It is composed by barrels where media (grossly called woods), abrasive pastes and pieces to be treated are inserted.

With a constant and regular movement, the tumbler moves the barrel, filled by media, abrasive pastes and materials to be treated. This movement causes a friction that will grind, smooth, polish or shine the surface of the objects to be treated.

Every material has its own cycle, according to its inherent features (stronger materials need specific media and abrasive pastes different from those used in the softer materials tumbling). The action on the surface to be treated is always carried out mechanically, thanks to the friction created in the quantity of media when the tumbler is put in motion, for rotation or vibration.

Rotating tumbler

The dry tumbler is a so-called rotating tumbler. This tumbler is composed by one or more barrels filled by woods (technically called media) and abrasive compounds.

Vibro tumbler – Wet tumbler

The vibro tumbler (or wet tumbler) is different from the rotating tumbler for the presence of water in the barrel, for its motion that generates vibrations instead of rotations and for the presence of chips instead of woods. This kind of tumbler is more indicated for the treatment and polishing of metal.

Advantages of tumbling process

This kind of work allows to treat simultaneously more pieces (for example 40-100 eyewear front pieces in the dry rotating barrels, or a hundred of metal parts in the vibro tumblers), guaranteeing an uniform and regular finishing on the complete surface.

Do you need an advice for the polishing phase or a process to treat a specific material? Contact us!

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