Compression Set Apparatus

Compression set of Rubber components is defined as the difference between the original thickness of a test specimen taken either from the component or moulded from the compound from which the component is to be moulded and that after compression and subsequent recovery, expressed as percentage of the initially applied compression. It to retain its elastic property after prolonged compression.
The compression set may be determined after subjecting the test specimen either to a constant deflection or pressing it under a constant load. Compression set under constant deflection is determined by subjecting a cylindrical disc shaped test specimen to a fixed strain for a specified time at either room temperature or any other specified temperature, and then allowing it to recover for a given time.
The “PRESTO” Compression Set Apparatus for determination of compression set under constant strain consists of four steel plates having flat and parallel ground faces. The plates are held together by a pair of allen bolts. Ring shaped spacers of specified thickness made of magnetic stainless steel are provided to give the desired compression to the test specimens. The apparatus may be kept inside a hot air oven for conducting the test at elevated temperatures.