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Durometer Hardness Test

13 May 2024 Posted by: makeyourmark New Technologies

“Durometer” is a term that refers to an instrument used to measure the hardness of materials, particularly elastomers such as rubber and plastics. It is also used to describe the measurement of hardness itself. The durometer hardness test is a widely used method in various industries to assess the firmness or stiffness of materials. The durometer hardness test is essential to quality control and material selection processes, ensuring that products meet the required hardness specifications for their intended applications. Industries such as automotive, construction, and manufacturing rely on durometer testing to ensure the durability and performance of their products.

What is a durometer?

As briefly stated before, a durometer is a tool that can be used to measure the hardness of a material such as rubber, silicone, or other elastomer. The first durometer was invented by Albert F. Shore in the 1920s. Shore, an engineer working for the Shore Instrument & Manufacturing Company, developed the instrument to address the need for a standardized method to measure the hardness of rubber and other elastomeric materials. Over the years, improvements have been made to durometer design and technology to enhance accuracy and reliability. Digital durometers, for example, have become more common, offering precise readings and greater convenience compared to traditional analog instruments. Additionally, advancements in materials science and manufacturing have led to the development of specialized durometers for specific applications, further expanding the instrument’s utility in various industries.

Durometers are usually comprised of a gauge with a needle or digital display, a spring-loaded indenter, and a hardness scale, offering a standardized means of hardness measurement. The most common types of durometers are Shore A and Shore D durometers, each designed for particular applications based on the material’s hardness. Shore A durometers, for instance, are employed for softer materials, while Shore D durometers are used for harder materials. Since their development, durometers have provided a standardized method for hardness measurement, streamlining and improving quality control and material selection processes. 

Durometer Testing

The durometer hardness testing process begins with pressing the indenter into the material with a standardized force, then measuring the depth of penetration. That depth is subsequently converted into a hardness value using a specific durometer scale. Factors such as the material’s composition, temperature, and surface finish may affect the accuracy of the hardness measurement, so it is important to standardize testing procedures to ensure consistent and reliable results. Inaccurate durometer measurements can lead to the selection of unsuitable materials for specific applications, potentially resulting in product failure, safety hazards, and increased costs for manufacturers. 

Durometer Chart

Durometer charts are a graphical representation of hardness values for different materials, typically displayed in a tabular format. The chart provides a visual reference for comparing the hardness of various materials and is commonly used to select materials that meet the required hardness for specific applications. The chart typically lists materials along the vertical axis and hardness values along the horizontal axis, with each material assigned a hardness value based on durometer testing. 

Durometer charts are not standardized and can vary between companies and manufacturers. Each manufacturer may use its own chart based on its specific testing methods and standards. Therefore, it is important for users to consult the specific durometer chart provided by the manufacturer of the durometer being used to ensure accurate and reliable hardness measurements.

Read more about rubber and silicone on our blog page or learn more about ILT, the world leader in manufacturing seals and septa here.