Rubber Hardness Scale

Shore durometer is a scale used industry wide to measure the hardness of rubber and plastic materials.

Rubber hardness scale. Hardness may be defined as a material s resistance to permanent indentation. For example a material with a shore hardness of 95a is also a shore 50d. The shore a hardness scale measures the hardness of flexible mold rubbers that range in hardness from very soft and. The shore 00 hardness scale measures rubbers and gels that are very soft.

Named after its inventor albert ferdinand shore shore hardness offers different scales for measuring the solidity of different materials shore was born in 1876 and lived until 1936 creating the shore scale in the 1920s. As you can see from the chart below there is overlap on the different scales. Lower numbers indicate less resistance and softer materials. Shore durometer hardness is a measure of the resistance a material has to indentation.

Two such scales using slightly different measurement systems are the shore a and shore d scales. The hardness of rubber measured by means of a durometer is expressed in the unit shore a. Tpes can range from 10 shore 00 up to 72 shore d spanning all three hardness scales however the most commonly used is the shore a scale. Hardness is one of the most commonly used properties to specify a rubber.

There are several scales to measure the hardness of an elastomer used for materials with different properties shown in the diagram below. Elastomeric materials are usually measured with either a shore a scale durometer or an irhd dead load system. Shore who developed a measurement device called a durometer in the 1920s. Hardness is an important consideration in sealing materials.

Generally most rubber materials fall under the rubber durometer scale of shore a. The shore durometer is a device for measuring the hardness of a material typically of polymers elastomers and rubbers. The most commonly used gauges for measuring the hardness of rubber are the durometer and the irhd meter. A flattened cone is pressed through a spring into the surface of the rubber.

Shore hardness and how it relates to other properties. For example a material with a shore hardness of 95a is also a shore 45d. These tests are designed for use with samples approx 6mm thick and a surface area sufficient to permit at least 3 test points 5mm apart 13mm from any edge. Thus if you need a rubber or o ring durometer that feels like a running shoe sole review our rubber hardness chart below then pick shore 70a.

The durometer scale was defined by albert f. As you can see from the graphic there is overlap on the different scales. A rubber durometer of shore 70a is the most commonly chosen material hardness for all applications. Some of hapco s materials are available in both shore a and shore d.

Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials.