Polymer Hardness Testing Methods
There are three distinct methods for determining polymer hardness:
1. Brinell Hardness Testing (ASTM E10)
· A hardened steel ball is made to strike the surface of the specimen in an attempt to make a notch on the surface as part of the Brinell hardness test.
· The lever mechanism is used to apply the weight.
· The Brinell hardness number will be used to calculate the material’s hardness.
· Brinell hardness number = Load/Curved Indentation Surface Area.
2. Rockwell Hardness Testing (ASTM E18)
· In the Rockwell test, the hardness of the material is assessed by measuring the depth of penetration.
· The remaining procedures are identical to those used in Brinell hardness testing, however, the formula for calculating the Rockwell hardness number (Rhn) differs slightly. The Rockwell hardness testing device has a dial indicator for the Rhn reading.
· There are two scales that are used to compare the hardness of soft and hard materials, with the penetrator (indenter) varying depending on the hardness and softness of the materials (diamond cone).
3. Vickers Hardness testing (ASTM E384)
· The diamond pyramid hardness test is another name for the Vickers hardness test. because the diamond pyramid serves as the indenter.
· The indenter need not be changed for different materials, unlike Brinell hardness testing.
· The load applied to the indentation’s surface area yields the Vickers hardness number.
Limitations of Polymer Hardness Testing
- Limitations of Brinell Hardness Test
· This method is inappropriate for finished products due to an indentation on the specimen or the testing component.
· We can only test materials with low or medium hardness as deformation of the steel ball is not permitted.
- Limitations of Rockwell Hardness Test
· This method is inappropriate for finished products due to an indentation on the specimen or the testing component,although, as compared to the Brinell hardness test, the indent impression is quite modest.
· The scale name must always be used as a prefix when referencing the Rockwell hardness number (Rhn).
- Limitations of Vickers Hardness Test
· This procedure is occasionally inappropriate for finished items due to an indentation on the specimen or the testing component, although the indent impression is not as large as the Brinell hardness test.