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Durometer Testing

June 19, 2020

Durometer Testing
Performing a durometer test means that you’re testing the hardness of the material, using a “duro-meter” measurement device. It’s used to measure the hardness of most non-metallic materials, like rubber and plastic. Knowing the hardness of a material is very important in an application because it can help determine what material would perform best. However, it should not be used to measure resistance to wear.
The test scale was created to offer a reference point when evaluating materials. The test assists in describing the properties of a material’s resistance to indentation, which tells how hard it is. It is a quick screenshot of how the material will perform under compression, impact and or abrasion.

What are Shore scales?
Once the hardness of the material is measured you can determine where it is on the durometer scale. There are 12 different scales, but Shore A and D are the most common. Shore A is for softer rubbers and Shore D are for harder rubbers. For an example, a rubber nipple for a bottle would be in the Shore A category and a grocery cart wheel would be in the Shore D category.
What about bendable rubbers?
Of course, there isn’t one, single way to measure the hardness of a material. While they’re designed to offer a reference point for anyone using rubber or plastics, the scales are slightly different.

When it comes to bendable rubbers, for example, the Shore A hardness scale will be used. Measuring the solidity of the material – since they can vary widely – the scale offers helpful data which can be used to great effect by engineers.

Performing the Test
1. Place the material on a flat and hard surface.
2. Put the durometer to the material so that the indenter touches it.
3. Push down until firm contact is made with the material.
4. Take a reading.

Durometer testing offers an effective way to distinguish different rubber products, for control purposes, to categorize materials into performance groups. Indentation hardness values on the Shore scales produced by the durometer test do not correlate to other fundamental performance characteristics of rubber or plastics such as strength, abrasion resistance, or compression set resistance. But indentation hardness tests do correlate to the elastomer’s flexural modulus. Thus, Shore hardness and flexibility can be distinguishing characteristics on which to build an application foundation plan, followed by testing to validate those plans.