BS ISO 07267-3:2011 pdf free download – Rubber-covered rollers – Determination of apparent hardness Part 3: Pusey and Jones method.
The hardness of a roller covering has traditionally been determined on the finished roller, since it is this hardness that is critical to the correct functioning of the roller in its end application. Values of hardness, determined by whichever method is chosen, are therefore dependent not only on the method employed and on the rubber, but also on the diameter of the roller, on the thickness of the covering and, in the case of thin coverings, on the nature of the roller core. For this reason the term “apparent hardness” is used to distinguish between the values obtained by the methods described in the various parts of this International Standard and those that would be obtained for the rubber if it was possible to use the standard test methods for standard test pieces forming the subjects of other International Standards.
Since rollers vary considerably in size, construction and end use, and in view of the fact that hardness determinations are made for such different purposes as specification and factory process control, it has not been possible to standardize one test method. Consequently, three methods are described, each capable of standing alone (see Foreword).
4 Time-interval between vulcanization/finished grinding and testing
Tests shall be carried out not less than 16 h after vulcanization and/or finished grinding and, for arbitration
purposes, not less than 72 h after vulcanization (see ISO 23529).
5 Conditioning and temperature of test
Where possible, the test shall be carried out at standard laboratory temperature in accordance with ISO 23529. The product under test should be maintained under the test condition for sufficient time to reach temperature equilibrium with the test environment. Where this is impracticable, the period of time and the conditions shall be given in the product specification (see the Note).
The same temperature shall be used throughout any one test or series of tests intended to be comparable.
NOTE For large rollers having heavy metal cores, ambient conditions might not allow equilibrium temperatures to be
obtained.
6 Apparatus
6.1 Plastometer, consisting of a supporting frame, an indentor, a mass for applying a fixed gravitational force on the indentor, a depth indicator and a specimen holder.
6.1.1 Supporting frame, so configured that the indentor and mass can be independently raised or lowered vertically, permitting the indentor to rest on the surface of the test roller and the mass to be applied subsequently to the indentor.
6.1.2 Indentor, consisting of a vertical steel shaft attached at the upper end to the spindle of the indicator gauge and having at the lower end a steel ball. The steel ball shall be (3,175 ± 0,015) mm in diameter and shall be made of highly polished, non-corrosive hard metal properly treated to resist wear.
6.1.3 Mass,of(1 000 ±2)g.
6.1.4 Depth indicator, comprising a dial gauge or other suitable device graduated in increments of 0,01 mm and having a range of at least 3 mm to indicate the movement of the indentor.