The feel of softness of any flexible foam is quantitatively defined by its indentation hardness. Indentation hardness of foam is determined by pressing a circular indentor at a specified speed against a block of foam and finding the force needed to compress it to a specified percentage of its initial thickness.
The PROLIFIC Indentation Hardness Tester for polyurethane foam consists of a circular indentor which can be pressed against the foam block under test, a motorized arrangement to move the indentor, and a load indicating arrangement to indicate the load being exerted by the indentor on the foam block at any instant.
The indentor is in shape of a circular disc and is mounted on a self-aligning ball bearing to ensure that it sits parallel to the surface of the test specimen. It is mounted at the lower end of a screw, which can be raised or lowered at a specified speed with the help of a motor and worm reduction gearbox. An arrangement to stop the motor at extreme ends of travel of the indentor is provided.
The downwards movement of the indentor is measured with the help of a pre-set type digital displacement meter, which can be set at any desired value to stop the motor automatically at a desired displacement. A linear scale is provided to indicate the gap between the bottom face of the indentor and the loading platform. The indentor can also be moved by hand to apply the initial load.
The load platform is made of cast aluminium and has a large number of holes arranged in a grid for rapid escape of air during compression. It is mounted on shear beam type load cell. A digital load indicator is provided to indicate the load acting on the test specimen.
The equipment is finished in grey hammertone stoving painting and bright chrome / zinc plating to give it a corrosion resistant finish.
|TECHNICAL DATA |
|Area of Indentor ||323 cm² |
|Diameter of indentor ||202.8 mm |
|Maximum thickness of test specimen that can be tested ||150 mm |
|Measurement of load ||0 - 100 kg x 0.1 kg |
|Measurement of travel ||0 - 150 mm x 1mm |
|Speed of movement of indentor ||150 mm/minute * |
|Motor ||¼ HP single-phase 230 volts AC |
|RELATED STANDARD |
|IS 7888 - 1976 ||Methods of Test for Flexible Polyurethane Foam |