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ISO 868 Plastics and ebonite - Determination of indentation hardness by means of a durometer (Shore hardness)
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Mechanical
ISO 868 Standard Description
ISO 868 Plastics and ebonite - Determination of indentation hardness by means ofAdurometer (Shore hardness)
ISO 868 Standard Introduction
ISO 868 specifies a standard method for determining the hardness of plastics and hard rubber. The method evaluates material hardness through indentation measurement using a durometer and has been widely recognized. ISO 868 is used by manufacturers and producers for quality control and is an important standard in the quality assurance process of plastic and hard rubber products.
ISO 868 Scope of Application
ISO 868 applies to the determination of hardness of plastics and hard rubber.
ISO 868 Shore Hardness
Shore hardness is an indicator used to measure a material’s resistance to indentation using a standard indenter. It is commonly applied to rubber, plastics and similar materials. Different durometers are used according to different material types. Generally, a higher Shore hardness value indicates a harder material, while a lower value indicates a softer material. Shore A and Shore D durometers are the most commonly used types in the rubber and plastics industries.
(1) Shore A (Type A) Durometer
Primarily used for measuring softer plastics, such as polyolefins, fluoropolymers and certain vinyl materials. It is suitable for materials ranging from extremely soft rubber-like materials (close to Shore A 0) to semi-rigid plastics (approximately Shore A 90–95).
(2) Shore D (Type D) Durometer
Primarily used for harder rubber materials and thermoplastic elastomers. Materials below approximately Shore D 50 (roughly equivalent to Shore A 95) are generally measured using a Shore A durometer, although Shore D can also be used. Materials above Shore D 65 tend to be rigid and non-flexible. When the Shore D range is exceeded, Rockwell hardness testing is often used for harder engineering plastics such as nylon and polyoxymethylene (POM).
In summary, Shore A (Type A) durometers are used for softer materials such as rubber and soft plastics, while Shore D (Type D) durometers are suitable for harder materials such as hard plastics and thermoplastics.
ISO 868 Test Method
Hardness testing is performed by pressing an indenter into the material under specified conditions and evaluating the material properties based on the indentation depth. Hardness is inversely related to indentation depth and is also influenced by the elastic modulus and viscoelastic properties of the material. The shape of the indenter, applied load and loading duration can affect the test results. The test procedure is as follows:
Specimen Placement: Place the specimen on a hard, flat surface. Ensure that the distance between the indenter and the specimen edge is at least 9 mm.
Load Application: Press the durometer vertically onto the specimen, ensuring that the presser foot is in full contact with the specimen surface. The operation shall be performed quickly and without impact. Apply only sufficient pressure to achieve stable contact.
Reading: Read the hardness value 15 ± 1 seconds after the presser foot contacts the specimen. For instantaneous readings, record the value within 1 second. If the durometer is equipped with a maximum hold indicator, record the maximum reading.
Multiple Measurements: Perform five measurements at different locations on the specimen. The distance between measurement points shall be at least 6 mm. The average value of the five readings is reported as the result.
Notes:
(1) When the Type A durometer reading is greater than 90, it is recommended to use a Type D durometer.
(2) When the Type D durometer reading is below 20, it is recommended to use a Type A durometer.
(3) To improve test repeatability and accuracy, a stand or additional weight may be used. Recommended weights: 1 kg for Type A and 5 kg for Type D.
SATISFY has a professional technical team specializing in building material testing and provides testing services for building materials according to various international standards. Our services include technical consultation, standard interpretation, sample testing, report review and product improvement recommendations. For more information, please contact SATISFY.
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