DIN ISO 48:2015 pdf free.Rubber, vulcanized or thermoplastic -Determination of hardness (hardness between 10 IRHD and 100 IRHD] [ISO 48:2010].
5 Apparatus
5.1 General
Calibration and verification of the apparatus shall be performed in accordance with ISO 18898.5.2 Methods N, H, L and M
The essential parts of the apparatus are as specified in 5.2.1 to 5.2.6, the appropriate dimensions and forces being shown in Table 1.
5.2.1 Vertical plunger, having a rigid ball or spherical surface on the lower end, and means for supporting the plunger so that the spherical tip is kept slightly above the surface of the annular foot prior to applying the contact force.
5.2.2 Means for applying a contact force and an additional indenting force to the plunger. making allowance for the mass of the plunger, including any fittings attached to it, and for the force of any spring acting on it, so that the forces actually transmitted through the spherical end of the plunger are as specified.
5.2.3 Means for measuring the increase in depth of indentation of the plunger caused by the indenting force, either in metric units or reading directly in IRHD.
The gauge employed may be mechanical, optical or electrical.
5.2.4 Flat annular foot, normal to the axis of the plunger and having a central hole for the passage of the plunger.
The foot rests upon the test piece and exerts a pressure on it of 30 kPa ± 5 kPa provided that the total load on the foot does not fall outside the values given in Table 1. The foot shall be rigidly connected to the indentation-measuring device, so that a measurement is made of the movement of the plunger relative to the foot (i.e. the top surface of the test piece), not relative to the surface supporting the test piece.
5.2.5 Means for gently vibrating the apparatus, for example an electrically operated buzzer, to overcome any slight friction. (This may be omitted in instruments where friction is effectively eliminated.)DIN ISO 48 pdf download.