ASTM D2240 is a test method designed to test the depth of an indentation in the material being tested. The indentation is created by a given force on a standardized indentation head. The depth is proportional to the material hardness, its ductility and the shape of the indentation head. Using rubber properties and a durometer hardness, the ASTM D2240 consists of pressing the indentation head at the bottom of the handheld device until the flat bottom part is resting on the material’s surface to be tested.
ASTM D2240 uses and factors to be considered
ASTM D2240 allows for a measurement of the initial hardness, or the indentation hardness, after a given period of time. The test requires applying the force in a consistent manner, without shock, and measuring the hardness. There are 12 scales and there is no mathematical relation between the various scales as they are arbitrary scales. It is therefore important to know which scale you need the laboratory to use.
ASTM D2240 typical test parameters
- Initial hardness or timed hardness: Usually initial
- Specimen shape: Flat & homogeneous (no texture)
- Durometer scale to be used: The most popular durometer scales are “A” and “D”. These two scales combined together cover a hardness range from rubbers to nylons.
- Number of specimens per product: 1 specimen, 5 readings
- Specimen dimensions: 2” X 2” or more with a minimum thickness of 6.4 mm (0.25 inches) thick.
- Conditioning and testing Temperature: 23 ± 2 °C
- Conditioning and testing relative humidity: 50 ± 5%
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