International Rubber Hardness Scale

The reading from a dead load hardness meter is called international rubber hardness degrees irhd.

International rubber hardness scale.

The international rubber hardness degrees irhd scale has a range of 0 to 100 corresponding to elastic modulus of 0 0 and infinite 100 respectively. There are other shore hardness scales such as shore o and shore h but they are rare within the plastics and rubber industry. If the indenter penetrates 2 54 mm 0 100 inch or more into the material the durometer is 0 for that scale. The measurement is made by indenting a rigid ball into the rubber specimen.

The readings range from 30 to 95 points. The international rubber hardness degrees irhd scale has a range of 0 to 100 corresponding to the elastic modulus of 0 0 and infinite 100 respectively. The standard test method conducted involves pressing a piece of rubber with a known force for a given time and measure how much the rubber indents in that time. In europe the iso 48 standard and the irhd unit are often used to determine hardness.

The irhd international rubber hardness degrees instrument has a spherical indentor which indents the sample under a minor and major load. A number of instrument types exist for both the irhd micro dead load and shore a scales are most commonly used for rubber. The spring loaded meter gives shore a values. The irhd international rubber hardness degree scale and the shore scale are widely used.

Generally most rubber materials fall under the rubber durometer scale of shore a. The shore a scale is used for softer rubbers while the shore d scale is commonly used for harder ones. When comparing two materials shore hardness offers a reference point and there are 12 different scales that are used for measuring a range of substances. The displacement irhd degrees conversion table is published in iso 48.

A rubber durometer of shore 70a is the most commonly chosen material hardness for all applications. The hardness of seal materials such as rubbers plastics and elastomers are measured in units of shore or irhd international rubber hardness degrees. The shore a scale is the most prevalent in the united states. The hardness is measured by the depth of indentation caused by a rigid ball under a spring load or dead load the indentation being converted to hardness degrees on a scale ranging from 0 to 100.

The final value of the hardness depends on the depth of the indenter after it has been applied for 15 seconds on the material. Determining the hardness of rubber with an irhd meter. The irhd m micro is mainly used where the test material has a standard thickness of 2 mm. The differential indentation depth is measured and tabulated to read directly in irhd degrees.

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. Hardness is one of the most widely measured properties used to characterise rubber.