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Select an IRHD Hardness Tester
Once IRHD is confirmed as the right method rather than a Shore durometer check, the buying decision comes down to the specimen, not the display. IRHD testing is governed by ISO 48 and ASTM D1415, with specimen preparation and conditioning under ISO 23529 — and in rubber and elastomer QC for seals, gaskets, O-rings and vibration mounts, most disputed readings trace back to two things: the anvil effect on specimens thinner than the method allows, and readings taken before the rubber has been conditioned. Settle the specimen and the standard first, and the platform follows.
If you are not yet certain IRHD is the right route, start with Choose Between Shore and IRHD; this guide assumes IRHD is already the method and the only remaining choice is the instrument.
1. How to Choose
Specimen thickness is the decision that splits the range:
- Thin sections, O-rings and small mouldings (roughly 1–5 mm) point to the micro method, where the indentation stays small enough to read a thin part before specimen support starts to bias the result.
- Thicker specimens and broader laboratory work (6 mm and up) point to the macro platform, which also spans several IRHD scales and Shore A from one bench.
- Confirm that fixturing, centring devices and specimen-support accessories are part of the real purchase — on an IRHD bench they usually are, not an optional extra.
2. Typical Product Fits
Two motorised, PC-controlled systems cover most IRHD work, split by specimen thickness:
- IRHD — the Type M micro system for very thin elastomers (1–5 mm), reading to 0.1 IRHD with automatic load sequencing that takes operator force out of the result. The choice when thin parts dominate the workload. (ISO 48, ASTM D1415.)
- Macro IRHD — for specimens of 6 mm and above, with interchangeable inserts (IRHD Type N, H and L plus Shore A) so one platform covers macro IRHD and durometer hardness. The choice for thicker specimens and mixed-scale laboratory work. (ISO 48, ASTM D1415, DIN 53505.)
3. Special Cases
A few situations are worth checking before you order:
- For O-rings and thin sections, confirm the specimen support and centring geometry first — the anvil effect biases a reading badly when the part is too thin or unsupported, which is exactly where the micro system earns its place.
- Condition the rubber to the specified temperature and time before testing; an unconditioned specimen reads differently and is the most common source of argument over a result.
- For mixed workloads, the Macro IRHD's interchangeable inserts avoid buying separate instruments for IRHD and Shore A — worth weighing against a dedicated micro system when your specimens span both regimes.
4. Next Step
For the wider rubber-hardness range and where each tester sits, return to Rubber Hardness (IRHD).
5. Related Knowledge
- Rubber Hardness (IRHD) — how the method works and where it fits.
- IRHD Measurement Principles — the dead-weight ball-indentation method behind the reading.
- IRHD Sample Preparation and Test Conditions — specimen thickness, conditioning and the conditions that decide repeatability.