ISO 48-4:2018 pdf download. Rubber, vulcanized or thermoplastic一Determination of hardness -Part 4: Indentation hardness by durometer method (Shore hardness).
8 Conditioning and test temperature
For all test purposes, the minimum time between vulcanization and testing shall be 16 h. Where iractical, test pieces shall be conditioned immediately before testing for a minimum period of 1 h at one of the standard lal)oratory temperatures specified in ISO 23529. The same temperature shall he used throughout any single test or Series of tests intended to he comparal)le.
9 Procedure
9.1 General
Place the test piece on a flat, hard, rigid surface (e.g. glass). Apply the iressure foot to the test piece, or vice versa, as rapidly as possil)le hut without shock, keeping the foot Parallel to the surface of the test piece and ensuring that the indentor is normal to the rubber surface.
9.2 Test time
Apply a force in accordance with 6.13 and 7.3 sufficient only to obtain firm contact between the pressure foot and the test piece and take the reading at the specifie(1 time after the pressure foot is in firm contact with the test piece. The standard test time is 3 s for vulcanized rubber and 15 s for thermoplastic rubber. Other test times may he used, provided they are stated in the test report. Rubbers of’ unknown types should he treated as vulcanized.
NOTE 1 A test time of 15 s has been introduced for thermoplastic rubber because the hardness value continues to decrease over i longer period of time than for vulcanized rubber, this test time being the same as that specified for plastics in ISO 868.
NOTE 2 If a flow curve is recorded [or at least 15 s (hardness every 0,1 s) for an unknown material, the appropriate measuring time (3 s or 15 s) can be selected instead of treating it as vulcanized.
9.3 Measurements
Make three (known material) or five (unknown material) measurements of hardness at different positions on the test piece at least 6 mm apart for types A, I) and AO and at least 0,8 mm apart lot’ type AM, and determine the median value.
If the time interval after which each reading was taken is different from 3 s, record the individual values of the indentation hardness together with the time interval after which each reading was taken, and determine the median value and the maximum and minimum values obtained.
10 Calibration and checking
10.1 Calibration
The instrument shall be calibrated regularly using suitable instruments for measuring force, indentation dept Ii a rid indenter geometry in accorda tice with ISO 48—9.
NOT[ Abrasive material can strongly wear the indenter. Therefore, recal ibration or replaceiiwnt o (lie indenter can be needed more often than the standard frequency.ISO 48-4 pdf download.