ISO 48-2:2018
Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: Hardness between 10 IRHD and 100 IRHD
Rubber, vulcanized or thermoplastic — Determination of hardness — Part 2: Hardness between 10 IRHD and 100 IRHD
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 23
- Дата публикации:
- 20 августа 2018 г.
- Издание:
- ISO IS 48 edition 1 version 1
- ICS:
- 83.060
This document specifies four methods for the determination of the hardness of vulcanized or thermoplastic rubbers on flat surfaces (standard-hardness methods) and four methods for the determination of the apparent hardness of curved surfaces (apparent-hardness methods). The hardness is expressed in international rubber hardness degrees (IRHD). The methods cover the hardness range from 10 IRHD to 100 IRHD. These methods differ primarily in the diameter of the indenting ball and the magnitude of the indenting force, these being chosen to suit the particular application. The range of applicability of each method is indicated in Figure 1. This document does not specify a method for the determination of hardness by a pocket hardness meter, which is described in ISO 48-5. This document specifies the following four methods for the determination of standard hardness. — Method N (normal test) is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD. — Method H (high-hardness test) is appropriate for rubbers with a hardness in the range 85 IRHD to 100 IRHD. — Method L (low-hardness test) is appropriate for rubbers with a hardness in the range 10 IRHD to 35 IRHD. — Method M (microtest) is essentially a scaled-down version of the normal test method N, permitting the testing of thinner and smaller test pieces. It is appropriate for rubbers with a hardness in the range 35 IRHD to 85 IRHD, but can also be used for hardnesses in the range 30 IRHD to 95 IRHD. NOTE 1 The value of the hardness obtained by method N within the ranges 85 IRHD to 95 IRHD and 30 IRHD to 35 IRHD might not agree precisely with that obtained using method H or method L, respectively. The difference is not normally significant for technical purposes. NOTE 2 Because of various surface effects in the rubber and the possibility of slight surface roughness (produced, for example, by buffing), the microtest might not always give results agreeing with those obtained by the normal test. This document also specifies four methods, CN, CH, CL and CM, for the determination of the apparent hardness of curved surfaces. These methods are modifications of methods N, H, L and M, respectively, and are used when the rubber surface tested is curved, in which case there are two possibilities: a) the test piece or product tested is large enough for the hardness instrument to rest upon it; b) the test piece or product tested is small enough for both the test piece and the instrument to rest upon a common support. A variant of b) would be where the test piece rests upon the support surface of the instrument. Apparent hardness can also be measured on non-standard flat test pieces using methods N, H, L and M. The procedures described cannot provide for all possible shapes and dimensions of test piece, but cover some of the commonest types, such as O-rings.
Abstract
Overview - ISO 48-2:2018 (Rubber hardness 10–100 IRHD)
ISO 48-2:2018 specifies standardized methods to determine the hardness of vulcanized or thermoplastic rubber expressed in International Rubber Hardness Degrees (IRHD). The standard covers hardness measurements in the range 10 IRHD to 100 IRHD and includes both procedures for flat (standard) test pieces and modified procedures for curved or small components (apparent hardness).
Key topics and technical requirements
- Hardness scale: Results reported in IRHD; standard hardness vs apparent hardness are distinguished and reported to the nearest whole IRHD.
- Four standard methods (flat surfaces):
- Method N (Normal) - suited to ~35–85 IRHD (usable 30–95 IRHD).
- Method H (High-hardness) - suited to ~85–100 IRHD.
- Method L (Low-hardness) - suited to ~10–35 IRHD.
- Method M (Microtest) - scaled-down N for thinner/smaller test pieces; similar range to N.
- Four apparent-hardness methods for curved/small parts: CN, CH, CL, CM - adaptations of N, H, L, M for cylindrical, double-curved, O-rings and similarly shaped articles.
- Indentation principle: Hardness is derived from the difference in indentation depths of a spherical indentor under specified small and large forces. Methods differ mainly in indenter ball diameter and indenting force, chosen to suit material hardness and geometry.
- Test conditions and specimen requirements: Clauses cover test-piece dimensions, thickness limits, conditioning, temperature control, number of readings, expression of results, precision and test-report content.
- Limitations noted: Microtest and apparent-hardness readings can differ from standard flat-piece results due to surface effects, curvature and support conditions; differences up to several IRHD are possible and, in extreme cases, larger (noted for shaped articles).
Practical applications and users
- Who uses it: Material and quality engineers, rubber product manufacturers, test laboratories, R&D teams, and procurement/specification writers who need repeatable rubber hardness data.
- Typical uses:
- Quality control of vulcanized and thermoplastic rubber components (seals, O-rings, gaskets).
- Specification and acceptance testing during production and incoming inspection.
- Comparative material assessment in product development.
- Hardness testing of small or curved parts where standard slab tests are impractical.
- Practical value: Provides reproducible, internationally recognized hardness values for stiffness assessment, material selection, and compliance with procurement or regulatory requirements.
Related standards and references
- ISO 48-1 (guide to hardness testing)
- ISO 48-5 (pocket hardness meter)
- ISO 48-9 (calibration and verification of hardness testers)
- ISO 23529 (preparing and conditioning test pieces)
- ISO 1382 (rubber vocabulary)
Keywords: ISO 48-2:2018, rubber hardness, IRHD, hardness testing, vulcanized rubber, thermoplastic rubber, methods N H L M, apparent hardness, hardness of O-rings.
Технические детали
- Технический комитет
- ISO/TC 45/SC 2 - Testing and analysis
- SKU
- ISO 48-2:2018
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