IRHD stands for International Rubber Hardness Degree [°] that can be measured with this method. The M in IRHD-M stands for micro, which means that very small rubber samples and products with a thickness of 1 mm or more can be determined. It can therefore be determined how hard small elastomer, plastic or rubber products, e.g. O-rings or coatings, are. In addition, there are the IRHD processes in the N, H, L, M and VLRH versions.
The degree of hardness provides information on the deformation behavior as a result of a constant load and can therefore provide conclusions about the functionality of small parts. The geometry of the test body is a sphere, which is why we often speak of the ball indentation hardness IRHD.