What Is Shore Hardness? Rubber A/D Scale and ISO 868 Standard
Verified by Rachel Mayfield, Supply Chain Analyst - April 2026
What's Shore Hardness?
Shore Hardness is a scale measuring the hardness of rubber and elastomers, commonly shore A (flexible) and shore D (rigid). This scale uses indentation depth to determine material stiffness under applied force, with higher numbers indicating harder materials.
The Shore Hardness test measures the resistance of a material to an indenter penetrating its surface. It's particularly useful for determining the performance characteristics of rubber components in various applications. For instance, a lower shore value like 20A is suitable for flexible seals and gaskets that require high elasticity, while a higher shore value such as 70D might be used for mechanical parts needing durability and resistance to wear.
The test follows ISO standards, specifically ISO 868:2017 and ISO 7619-1:2013. These standards provide precise methods for measuring the hardness of materials like rubber and elastomers using Shore A and D scales, respectively. In the UK, BS EN ISO 868 covers this testing method.
Typical values range from as low as 5A to over 100D on the scale. Common applications include O-rings (often around 70A), conveyor belts (ranging from 40-60A for flexibility and wear resistance), and engine mounts (typically around 85A for vibration dampening). Maintenance engineers use Shore Hardness values to select components that meet specific application needs, such as sealing in hydraulic systems or damping vibrations in machinery.
Frequently Asked Questions
What is Shore Hardness?
A scale measuring the hardness of rubber and elastomers, commonly Shore A (flexible) and Shore D (rigid).
What exactly is Shore Hardness and why is it important for engineers?
Shore Hardness is a measurement scale used to determine the hardness of rubber and elastomers, using indentation depth. It's important for engineers because it helps in selecting materials based on their stiffness and flexibility, ensuring components like seals and gaskets perform adequately under various conditions.
What are the main types or variants of the Shore Hardness scale?
The primary types are Shore A and Shore D scales. Shore A measures softer and more flexible rubbers (from 5A to 95A), while Shore D is used for harder, rigid materials (from 10D to 100D).
How do engineers choose the right Shore Hardness value for their application?
Engineers consider the specific requirements of their project, such as flexibility and wear resistance. For instance, a lower shore value like 20A is ideal for flexible seals needing high elasticity, whereas higher values around 70D are suitable for mechanical parts that require durability.
Which standards does Shore Hardness testing follow in the UK?
Shore Hardness tests adhere to ISO standards ISO 868:2017 and ISO 7619-1:2013, with BS EN ISO 868 being the relevant British Standard for rubber hardness measurement.
Where can UK engineers source materials based on specific Shore Hardness values?
Engineers in the UK can find suppliers of rubber components with precise Shore Hardness ratings through companies listed under 'products' sections on industry websites or by contacting local manufacturers who specialize in rubber and elastomer products.
What does Shore Hardness measure and what are the common scales used?
Shore Hardness measures the hardness of rubber and elastomers by determining how deeply an indenter penetrates the material's surface under applied force. Common scales include Shore A for flexible materials and Shore D for rigid ones.
How do engineers choose between different Shore Hardness values for a project?
Engineers select a specific Shore Hardness value based on the application requirements, such as flexibility or durability. For example, a lower shore value like 20A is ideal for seals needing high elasticity, whereas a higher value around 70D might be necessary for parts that require greater wear resistance.
Which ISO standards govern the measurement of Shore Hardness in rubber and elastomers?
The ISO standards ISO 868:2017 and ISO 7619-1:2013 provide detailed methods for measuring Shore Hardness using scales A and D respectively. These standards ensure consistent and accurate hardness testing across various materials.
Where can UK engineers find suppliers for rubber components based on Shore Hardness specifications?
UK engineers can consult local industrial supply companies or manufacturers that specialize in rubber products to find parts with specific Shore Hardness ratings. Many suppliers provide detailed technical information and can assist in selecting the appropriate material hardness for given applications.