IRHD = International Rubber Hardness Degree
The International Rubber Hardness Degree according DIN ISO 48 – Part 1 is, beside the Shore hardness, another test method for the measurement of the rubber hardness. IRHD shows the resistance of a rubber specimen against the intrusion of a ball with a diameter of 2.5 or 5.0 mm respectively under a defined pressure.
We differentiate between sub-ranges soft and normal.
If the rubber products are very small you can apply the IRHD measurement according DIN ISO 48 – Part 2. You will use a small ball with a diameter of 0.4 mm.
| Sub range | IRHD range | Diameter measuring ball | Specimen thickness |
|---|---|---|---|
| soft | from 10 to 35 IRHD | 5,0 mm | 10-12 mm |
| normal | more than 35 IRHD | 2,5 mm | 6 bis 10 mm |
| IRHD normal | from 35 to 90 IRHD | 0,4 mm | 1,5 bis 2,5 mm |
The standard test specimens are platens with plat, parallel top and bottom surfaces.