Permanent Deformation Test Apparatus

Standards

ASTM D395, ISO 815, DIN 53517

What is a Permanent Deformation Test Apparatus?

The Permanent Deformation Test Apparatus measures the ability of rubber to return to its original thickness after being subjected to prolonged compression at a specific temperature and deflection.

As a rubber material is compressed over time, it loses its ability to return to its original thickness. This loss of elasticity (memory) can reduce the performance capability of an elastomeric seal, gasket, or cushion pad over a long period.

A permanent set that a gasket may develop over time can cause leakage; or in the case of a shock isolation pad, its ability to protect a device that has been accidentally dropped may be compromised.

Evaluation of Test Results

Permanent Deformation Test results for a material are expressed as a maximum percentage. The lower the percentage, the more resistant the material is to permanent deformation under a specific range of deflection and temperature.

Permanent Deformation Test results can be confusing because they are calculated differently under different test methods.

Measuring Permanent Deformation of Solid Elastomers

It is particularly used to test static compression for rubber. Place a standard specimen between parallel flat plates, tighten the screws, compress to a specific percentage range, then place in an oven for a certain period and measure its thickness after 30 minutes of cooling.

Permanent Deformation Test Apparatus Features