IRHD-Hardness (Method M – Microhardness)

The IRHD (International Rubber Hardness Degree) hardness testing method was developed for elastomers and thermoplastic elastomers especially. The total deformation is used for calculating material values at little loads.

For the ball-indentation hardness IRHD, according to standard DIN ISO 48, a distinction is being made between different methods that vary essentially in the diameter of the ball-indenter and the height of the load. The method M is used for the investigation of the microhardness. This is often called Micro-IRHD.

Specimen Preparation

  • Specimen requirements: smooth, flat, plan parallel, minimum thickness 2 ± 0.5 mm
  • Extraction from component parts

Testing Conditions

  • IRHD Hardness Tester ZWICK H 04.3105.600 + 610
    • 3 individual measurements
    • Measurement time of 30 s
    • Steel ball-indenter with a diameter of 0.395 mm
    • Preload: 0.0083 N
    • Testing load: 0.145 N
    • Air conditioning: standard climate (23 °C, 50 % humidity)

Accredited Standards

  • DIN ISO 48:
    Rubber, vulcanized or thermoplastic – Determination of hardness (hardness between 10 IRHD and 100 IRHD)


Dipl.-Wirtsch.-Ing. Stephan Arndt
Telefon: +49 (0)3461 30889-68



  • Shore hardness
  • Procedure M
  • Measurement of hardness of plastics


  • IRHD
  • Micro-IRHD
  • IRHD-Micro


  • DIN ISO 48

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