Standard Test Method for Rubber Property — Durometer Hardness
A polymer or plastic material's hardness refers to its
ability to resist deformation and/or wear as a result of pressure, impact or abrasion. Knowing
this value allows engineers to avoid using soft materials in applications that
require a part to withstand the aforementioned sources of deformation and/or wear.
Other hardness scales include Shore, Vickers, Brinell, and Knoop.
Possible reasons a company might test for hardness include:
Below you will find a brief description of the ASTM Test Method related to the topics covered above:
Significance and Use
This test method is based on the penetration of a specific type of indentor when forced into the material under specified conditions. The indentation hardness is inversely related to the penetration and is dependent on the elastic modulus and viscoelastic behavior of the material. The geometry of the indentor and the applied force influence the measurements such that no simple relationship exists between the measurements obtained with one type of durometer and those obtained with another type of durometer or other instruments used for measuring hardness. This test method is an empirical test intended primarily for control purposes. No simple relationship exists between indentation hardness determined by this test method and any fundamental property of the material tested. For specification purposes, it is recommended that Test Method D 785 be used for materials other than those described in 1.1.
1.1 This test method covers twelve types of rubber hardness measurement devices known as durometers: Types A, B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R. The procedure for determining indentation hardness of substances classified as thermoplastic elastomers, vulcanized (thermoset) rubber, elastomeric materials, cellular materials, gel-like materials, and some plastics is also described.
1.2 This test method is not equivalent to other indentation hardness methods and instrument types, specifically those described in Test Method D 1415.
1.3 This test method is not applicable to the testing of coated fabrics.
1.4 All materials, instruments, or equipment used for the determination of mass, force, or dimension shall have traceability to the National Institute for Standards and Technology, or other internationally recognized organizations parallel in nature.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. Many of the stated dimensions in SI are direct conversions from the U. S. Customary System to accommodate the instrumentation, practices, and procedures that existed prior to the Metric Conversion Act of 1975.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
- D1349 Practice for Rubber--Standard Temperatures for Testing
- D1415 Test Method for Rubber Property--International Hardness
- D374 Test Methods for Thickness of Solid Electrical Insulation
- D4483 Practice for Determining Precision for Test Method Standards in the Rubber and Carbon Black Industries
- D618 Practice for Conditioning Plastics for Testing
- D785 Test Method for Rockwell Hardness of Plastics and Electrical Insulating Materials
- F1957 Test Method for Composite Foam Hardness-Durometer Hardness
- ISO/IEC17025:1999 General Requirements for the Competence of Testing and Calibration Laboratories
durometer; durometer hardness; hardness; indentation hardness; micro durometer hardness; ICS Number Code 83.060 (Rubber)
( Download ASTM D2240 From www.ASTM.org )