A look at the media used in vibratory finishing

Vibratory finishing is a mass finishing technique that involves feeding parts into a vibratory machine with media of various compositions and sizes. The vibratory action causes the media to act like thousands of small files scrubbing the parts. 

Selecting the right media is a critical factor impacting the quality of the results achieved in any mass finishing operation. There are several options to consider, each with its own pros and cons.

• Mineral: One type of mineral abrasive is silica sand, which tends to break up quickly and create large quantities of dust, exposing the operator to health risks. To counter this hazard, silica sand for blasting is often coated with resins to control the dust. Due to these risks, however, the use of silica as an abrasive is not allowed in certain countries, including Germany, the United Kingdom, Sweden and Belgium. Another common mineral abrasive is garnet, which is more expensive than silica sand. However, it offers equivalent production rates, yet produces much less dust, eliminating the health risks. 
• Agricultural: “Soft” abrasives, such as crushed nut shells or fruit kernels, are often used to avoid damaging the underlying material when, for example, cleaning brick or stone, removing graffiti, or removing coatings from printed circuit boards being repaired.
• Plastic: Ideal for soft metals like brass and aluminium, as well as stringy materials, plastic media is useful for providing a smooth but dull finish. These media are long lasting, built to cut fast, and provide a fine finish.
• Ceramic: Ceramic tumbling media come in different shapes, sizes and compositions. They are used for fast deburring and tough metal removal, as well as the cutting of hard metals. When media of smaller dimensions are needed, ceramic media offer the best options. They are better than plastic media in supporting very heavy metal parts.
• Steel: Carbon or stainless steel media is used for burnishing, metal polishing, mirror finishing, tumbling, eliminating manual buffing and pre-plate applications. 

Vibratory finishing is one of the many services offered by Mississauga, Ont.-based Vibra Finish. To learn more about the media it uses, as well as proper media selection, contact Vibra Finish. 

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