Falling Sand Abrasion Tester
The Falling Sand Abrasion Tester (Model 820) is a rugged apparatus based on a design described in ASTM D 968 and other internationally recognized test standards. Abrasion results from abrasive particles falling through a guide tube and impinging the test specimen until the substrate becomes visible. Normally used to evaluate paints and other organic coatings, abrasion resistance is expressed in terms of the volume of abrasive required to wear through a unit thickness of the coating.
The top of the Falling Sand Tester apparatus is a funnel which holds the abrasive particles and includes a 60° tapered end that connects to the guide tube. The guide is a straight, smooth-bore tube which contains the abrasive particles as they fall. Specimens are fixed under the guide tube at a 45° angle in a receptacle that includes an opening at the bottom allowing the abrasive particles to be collected in a container. A sturdy base and support system hold the apparatus in a vertical position.
Although a variety of abrasive particles have been used, silica sand and various grades of silicon carbide continue to be most popular. To ensure reproducible results, the abrasives must be graded to a particular sieve size. Note: Silica sand is typically characterized by its roundness of grains and produces a slower rate of abrasion on organic coatings. It has been noted that for 3 mil dry film thickness, many of the older coatings would require 20 to 200 liters of silica sand to achieve a failure. Today’s more durable coatings may require up to 600+ liters of sand to wear-through. For an extremely durable coating, the Taber Rotary Abraser is preferred as the Falling Sand method tends to be laborious and time consuming with the handling of large quantities of abrasive.
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