Durometer

When we compare the properties between two or many materials especially plastic, elastomer or rubber, we often heard “Durometer,” but what is it? Does it important for the material? and how we measure it?

Durometer is the international standard for measuring the hardness for kind of elastomer and rubber material. There are a few different measurement scales, call Shores. There is Shore 00, Shore A, Shore D and others as well. It has scale range 0-100 in each Shore. The Shore A type durometer scale is commonly used for measuring the hardness of most elastomer material.

Durometer numbers simply represent a relative comparison of hardness between different but similar materials that have had their hardness measured using the same durometer scale, device and measurement standard. Material hardness is a material's resistance to being penetrated or permanently indented. It is obviously important to have some idea of how hard a material is before choosing it for your application.

At this point we understand what durometer is, but how it can be measured? First, we should know what the principle of its measuring is. For the principle of measuring the hardness is based on measuring the resistance force of the penetration of a pin into the test material under a known spring load. A ‘Shore Hardness' gauge has a needle on a spring protruding from one end. The needle is placed against the sample, and pressure is applied. Once the gauge is pressed firmly against the material and the needle has penetrated as far as it can go, the measurement needle will indicate the corresponding hardness measurement. The amount of penetration, maximum 2.5 mm, is converted to hardness reading on a scale with 100 units. However, per the ASTM Standard D 2240, readings below 10 and above 90 are not to be considered reliable and should be discarded. Therefore, it is important to select the appropriate Scale that will provide results between 10-90 units.

Now we able to confident selection the durometer for the plastic, elastomer or rubber that suit for our using or explain the reasons of selection.