Hardness refers to a material’s ability to resist indentation by a harder object on its surface. It serves as an indicator to compare the softness or hardness of various materials. The hardness of shoe soles and heels is measured using a Shore hardness tester. This article provides a brief introduction to the common types of Shore hardness testers and standard testing methods.
The commonly used Shore hardness testing standards for footwear include the following:
- ISO 48-4:2018
- ISO 868:2003
- GB/T 3903.4-2017
- GB/T 2411-2008
- GB/T 531.1-2008
- HG/T 2489-2007
- SATRA TM 205
1. Types of Shore Hardness Testers
According to different testing standards, Shore hardness testers can be categorized into types A, C, D, AO, AM, and OO.
Type C and AO are used domestically and internationally, respectively, with similar equipment parameters. However, the formulas used to calculate spring force vary slightly, which may result in minor differences in the testing results.
2. Applicable Materials for Shore Hardness Testers
The various types of hardness testers specified in the standards are each suited to different materials:
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Type
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ISO 48-4、GB/T 531.1
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ISO 868、GB/T 2411
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SATRA TM 205
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HG/T 2489
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GB/T 3903.4
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Scope
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Rubber, vulcanized or thermoplastic
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Plastics and ebonite
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Rubber and plastics
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Cellular materials for shoes
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Complete shoe outsoles and heels
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Type A
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Normal- hardness range
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Softer materials
Note: it is recommended that measurements be made with the type D durometer when values above 90 |
Most footwear materials
Note：measurements be made with the type D durometer when value above 90, type OO when value less than 10 |
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Rubber and softer plastic
Note：measurements shall be made with the type D durometer when value above 90 |
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Type C
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Cellular materials for shoes
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Cellular and foamed materials
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Type D
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High-hardness range
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Harder materials
Note: it is recommended that measurements be made with the type A durometer when values less than 20 |
Very hard material
Note：measurements be made with the type A durometer when value less than 40 |
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Harder plastic
Note: measurements shall be made with the type A durometer when value less than 20 |
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Type AO
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Low-hardness range and for cellular rubbers
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Type AM
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Thin rubber test pieces in the normal-hardness range
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Type OO
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Very soft material
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3. Differences in the use of Shore hardness tester
According to different testing methods, the value of hardness testing and the expression of results are different.
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ISO 48-4、GB/T 531.1
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ISO 868、GB/T 2411
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SATRA TM 205
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HG/T 2489
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GB/T 3903.4
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Procedure
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The standard test time is 3s for vulcanized rubber and 15s for thermoplastic rubber
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Read the scale of the indicating device after 15s±1s. lf an instantaneous reading is specified, read the scale within 1s.
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Type A/OO: Read the scale of the indicating device after 15s±1s. Type D: Read the scale of the indicating device after 1s.
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Read the scale of the indicating device after 1s.
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Read the scale of the indicating device after 3s.
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Measurements
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Make three or five measurements and determine the median value.
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Make five measurements and determine the mean value.
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Make five measurements and calculate the median value.
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Make at least three measurements and determine the median value.
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Make three measurements and calculate the mean value.
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It can be seen from the above that different hardness tester types and different detection methods will obtain different hardness values, which can not be directly converted between these values.
Note: The hardness of metal parts such as steel shanks used in shoes is tested by Rockwell hardness tester.
