1 Introduction
1.1 Importance of rubber hardness testing
Rubber is a material that is frequently used in consumer and industrial items, and the way it is made greatly affects how reliable and effective it is. One of rubber’s most fundamental physical characteristics, hardness is important for the creation, manufacturing, and use of rubber goods. Rubber’s elasticity, form stability, resistance to wear, and compatibility with other materials are all strongly impacted by its hardness. As a result, precise measurement and management of rubber hardness are essential to guaranteeing product quality and fulfilling particular application needs.
1.2 Overview of different rubber hardness test classifications
Rubber hardness may be divided into three primary categories based on the hardness testers and various testing techniques. Every kind has a different set of testing guidelines, procedures, and application range.
1.2.1 Duchenne hardness test
One of the most often used techniques for determining the hardness of rubber nowadays is the Duchenne test. Using a Duchenne hardness tester, this testing technique measures the elastic rebound of a rubber material after it has been strained in order to estimate the hardness value of the material. Different Duchenne hardness tester kinds, such as Duchenne A type and Duchenne D type, can be utilized, depending on the material and application requirements.
1.2.2 Barcol hardness test
For softer, thinner rubber materials, the Barcol hardness test is an appropriate method for measuring hardness. Rubber’s hardness is measured with a Barcol hardness tester, which indentates a sample to a predetermined depth while applying a constant pressure.
1.2.3 Rockwell hardness test
One popular method for assessing the hardness of metal, plastic, and some rubber materials is the Rockwell hardness test. This testing technique applies static or dynamic pressure to the sample’s surface and measures the depth of penetration using a Rockwell hardness tester to determine the rubber’s hardness.
1.2.4 IRHD hardness test
Rubber materials in a variety of hardness ranges may be tested for hardness using the globally recognized IRHD hardness test technique. Rubber’s hardness is measured using an IRHD durometer, which presses a sample and measures the depth of indentation. Based on varying hardness results, the IRHD hardness test is separated into two levels: IRHD-M (medium hardness) and IRHD-L (low hardness).
2. Duchenne hardness test
2.1 Duchenne A hardness test
2.1.1 Testing principles and methods
Duchenne One popular technique for measuring rubber hardness is the hardness test, which works well with softer rubber compounds. A Duchenne A-type hardness tester, which features a conical indenter and a needle-shaped pointer, was utilized for the test. Apply the hardness tester’s indenter vertically to the rubber sample’s surface during the test, then note the pointer’s indication. The tougher the rubber substance, the higher the number.
2.1.2 Scope and application areas
The Duchenne Rubber plastics, foam rubber, elastic rubber, and other softer rubber materials may all have their hardness determined with a hardness test. It is extensively utilized in the manufacturing and quality assurance procedures of rubber goods, including keyboard keys, pipes, gaskets, seals, and so on.
2.2 Duchenne D-type hardness test
2.2.1 Testing principles and methods
Harder rubber and plastic materials can be tested for hardness using the Duchenne D hardness test. The Duchenne D hardness tester is used for testing, much as the Duchenne A hardness tester. In addition to having a bigger indenter, the Duchenne D hardness tester offers a different reading range. Apply the hardness tester’s indenter vertically to the rubber sample’s surface during the test, then note the pointer’s indication. The tougher the rubber substance, the higher the number.
2.2.2 Scope and application areas
Rubber pipes, plastic goods, and other materials that are harder than rubber may all be measured using the Duchenne D-type hardness test. It is often used to assess the hardness and durability of materials in industrial seals, cable protection sleeves, automobile parts, etc.
3. Barcol hardness test
3.1 Testing principles and methods
A popular technique for determining the hardness of rubber is the Barcol test, which works well with softer and thinner rubber materials. A Barcol hardness tester with a dial and a cylindrical indenter is utilized for the test. The rubber sample’s surface is indented with the Barcol hardness tester’s indenter throughout the test, and the hardness of the rubber is determined by reading the hardness value on the dial. The rubber substance is harder the greater the hardness value.
3.2 Scope and application areas
Rubber sheets, coatings, films, and other thinner, softer rubber materials can all be measured using the Barcol hardness test. It is extensively utilized in the rubber goods sector as well as adjacent industries including electronics, building, cars, and aerospace. Rubber material’s hardness and surface strength are assessed by the Barcol hardness test, which aids in determining the material’s appropriateness and dependability.
In practical applications, barcol hardness testing has the following benefits: it is quick and easy to perform, doesn’t need sample preparation or destructive testing, and can be used to a variety of rubber materials with varying dimensions. To get accurate and trustworthy test results, it is important to keep in mind that the thickness, density, and surface quality of the material all have an influence on the Barcol hardness test findings. Therefore, it is important to take these aspects into account while applying the test.
4. Rockwell hardness test
4.1 Testing principles and methods
A popular technique for determining a material’s hardness is the Rockwell hardness test, which involves applying both static and dynamic stresses to the metal surface. A Rockwell hardness tester, which has an indicator and an indenter, is utilized for the test. In order to get the indenter to embed into the metal surface to a specific depth during the test, a predefined static load is applied initially. After that, the load is maintained constant and a smaller dynamic load is applied. One may measure the indicator’s reading to find a material’s Rockwell hardness value.
Several hardness scales, such as Rockwell hardness C, B, A, etc., are often available for the Rockwell hardness test. Different pressure heads and loads are used by different scales. For instance, heavy metal materials are often treated with Rockwell hardness C, but softer metal elements are better suited with Rockwell hardness B and A.
4.2 Scope and application areas
The Rockwell hardness test is useful for comparing and evaluating the hardness of different metal materials. It is extensively utilized in industries including product inspection, quality control, materials research, and metal processing. Materials with varying hardness ranges can be measured using different Rockwell hardness scales. For instance, strong metals like steel are best suited for Rockwell hardness C, but softer metals like copper, aluminum, and so forth are better suited for Rockwell hardness B and A.
The following are some benefits of using the Rockwell hardness test: it is quick and easy to do, doesn’t involve damaging samples, and can be used to a variety of metal materials. It can convert between several hardness scales and provide reliable hardness values. It should be noted, nevertheless, that the structure and surface condition of the material have an influence on the Rockwell hardness test findings. As such, the application should take these aspects into account to ensure accurate and trustworthy test results.
5. IRHD hardness test
5.1 Testing principles and methods
An globally recognized technique for determining the hardness of rubber materials is the IRHD hardness test. An IRHD hardness tester was utilized to measure the hardness during the test. An indicator and an indenter are part of the hardness tester. Apply a preset load while the indenter is embedded in the rubber sample’s surface for the test. Once you have held for some time, check the indicator’s reading. The rubber substance is harder the greater the hardness value.
The kind and hardness range of rubber materials determine the various testing procedures and standards used in IRHD hardness testing. IRHD N, IRHD H, IRHD L, and other common IRHD hardness testing techniques are used. Every method has a load and indenter that are unique.
5.2 Applications and characteristics of different levels
Various IRHD hardness grades have varied properties and application ranges, making them appropriate for various rubber material kinds.
IRHD N（Normal）
The IRHD N hardness test is appropriate for a wide range of rubber materials, such as synthetic, natural, and lower-hardness rubber. It is extensively utilized in the rubber goods sector, including rubber gaskets, pipelines, seals, and so on. The accuracy and reproducibility of IRHD N hardness tests are quite good.
IRHD H（High）
Harder rubber materials, such hard rubber and hard plastic, may be tested for hardness using the IRHD H hardness test. It is often used to assess the durability and wear resistance of rubber goods, including rubber rollers and tires. The bigger indenter and greater test load are features of the IRHD H hardness test.
IRHD L (Low)
Soft rubber, sponge rubber, and other softer rubber materials are appropriate for the IRHD L hardness test. It is frequently used to assess the suppleness and elasticity of rubber products, such handle covers and seat cushions. Both the test load and the indenter are smaller in the IRHD L hardness test.
6. Compare different classifications of rubber hardness testing methods
6.1 Test principle and measurement accuracy comparison
Barcol hardness test
Principle: Apply a static stress using a cylindrical indenter, then read the hardness value on the dial to determine the hardness of the rubber.
Measurement Accuracy: In comparison to other hardness testing techniques, the Barcol hardness test has a poor measurement accuracy.
Rockwell hardness test
Principle: Apply static and dynamic stresses using indenters of various scales, and then use the indicator’s reading to determine the metal’s hardness.
High measurement precision is provided by Rockwell hardness testing, particularly when assessing metal hardness.
IRHD hardness test
Principle: Apply a static stress using a designated indenter, then read the indicator to determine the rubber’s hardness.
Measurement accuracy: When evaluating rubber hardness, the IRHD hardness test provides a high measurement accuracy.
6.2 Comparison of applicable scope and application scenarios
Barcol hardness test
Application scope: Fits softer and thinner rubber materials.
Applications: Mainly utilized in rubber sheets, coatings, films, and other industries.
Rockwell hardness test
Application scope: Suitable for comparing and evaluating the hardness of different metal materials.
Application scenarios: Often utilized in the disciplines of product inspection, materials research, metal processing, and other related ones.
IRHD hardness test
Application scope: Fit for assessing the hardness of different kinds of rubber materials.
Application scenarios: Rubber gaskets, pipes, seals, and other goods made of rubber are widely utilized in this business.
6.3 Summary of advantages and disadvantages
Barcol hardness test
Benefits: The test is quick and easy to use, and it works with rubber materials of all sizes and forms.
Drawbacks: Poor measurement precision, influenced by surface quality, density, and material thickness.
Rockwell hardness test
Benefits: Offers excellent measurement precision and versatility for use with a range of metal materials’ hardness levels.
Cons: The test is not appropriate for softer rubber materials and is somewhat complicated.
IRHD hardness test
Benefits: Excellent measuring precision and compatibility with various rubber material kinds.
Cons: It isn’t appropriate for metal products. various material kinds require various corresponding testing procedures to be used.
