ASTM D395-18 pdf free. Standard Test Methods for Rubber Property—Compression Set.
These test methods cover the testing of rubber intended for use in applications in which the rubber will be subjected to compressive stresses in air or liquid media. They are applicable particularly to the rubber used in machinery mountings, vibration dampers, and seals.
3. Summar of Test methods
3. 1 A test specimen is compressed to either a deflection or by a specified force and maintained under this condition for a specilied lime and at a specitied temperature.
3.2 The residual deformation of a test specimen is measured 30 min after removal from a suitable compression device in which the specimen had been subjected for a definite time to compressive deformation under specified conditions.
3.3 After the measurement of the residual deformation, the compression set, as specified in the appropriate test method, is
calculated according to Eq 1 and Eq 2.
5.4 When the standard test specimen is to be replaced by a specimen taken from a vulcanized rubber part of greater thickness than the one indicated in 5. 2. l, the sample thickness shall be reduced first by cutting transversely with a sharp knife and ther followed by butting to the required thickness in accordance with Practice D3183.
5.5 An alternative method of preparing specimens is by plying up cylindrical disks cut from a standard sheet prepared in accordance with Practice D3182 using the specimen sizes specified in 5.2 I and cutting as described in 5.2.2, or where a drill press is not available cutting the specimens with a single stroke from a cutting die.
5.5.1 The disks shall be plied. without cementing, to the thickness h. flat, of uniform thickness, and shall not exceed seven in number for Type I specimens.
5.5.2 Care shall be taken during handling and placing of the plied test
parallel and at right angles to the axis of the cylinder.
5.5.3 The results obtained on plied specimens may be different from those obtained using solid specimens and the results may be variable, particularly if air is trapped between disks.
5.5.4 The results obtained on the specimens prepared by one of the methods may be compared only to those prepared by the same method.ASTM D395-18 pdf download.