What Is a Shore Hardness Tester?
A Shore hardness tester is a measuring instrument for measuring hardness, called “Shore hardness”.
Shore hardness mainly represents the hardness of metallic materials. Hardness is the property of a material to resist external forces. In everyday life, it is understood in the sense that steel is hard and rubber is soft. By using a shore hardness tester, the hardness of a material is quantified and expressed as “HS + number). The higher this number is, the harder the material is.
Compared to other hardness measurement methods, the measurement time is short and the measuring instrument is portable and easy to use. Therefore, it is used at various manufacturing sites.
Uses of Shore Hardness Testers
Shore hardness testers are used in a variety of industries. For example, they are used to select materials of appropriate hardness when making parts for automobiles and aircraft. They are also useful in checking the quality of rubber products such as shoes and tires.
In addition, it is indispensable when developing new materials in the field of research and development. To evaluate the performance of new materials, hardness is measured and compared with other materials. Shore hardness testers are also useful in quality control of products and in investigating causes of failure.
However, in Europe, the Shore hardness tester is not used much anymore. Instead, Vickers hardness testers, which can measure hardness more accurately, tend to be preferred. On the other hand, the Japanese JIS standard uses a method of converting Shore hardness to Vickers hardness. This is one of the reasons why Shore hardness testers are widely accepted in manufacturing sites in Japan.
Principle of Shore Hardness Testers
The Shore hardness tester determines Shore hardness by striking a sample with a hammer attached to a diamond hemisphere from a certain height and measuring the height at which the indenter bounces up after impact. The higher the bounce height, the higher the Shore hardness.
Since the Shore hardness tester mainly measures the amount of kinetic energy of the indenter, if the sample is too small, some of the kinetic energy is consumed by the vibration energy and accurate measurement may not be possible. The effect of the mass of the sample is called the “mass effect”. The Shore hardness tester is a measurement method with a large mass effect.
Another disadvantage of the Shore hardness tester is that there are many factors that can cause measurement errors, such as the need to drop the indenter perpendicularly to the sample and the surface in contact with the indenter must be horizontal. However, if you understand these features and are able to make as accurate a measurement as possible, the shore hardness tester, which can easily measure hardness, can be a useful tool in a variety of fields.
Types of Shore Hardness Testers
There are different types of shore hardness testers, such as the C-type and D-type. Each of these types has different characteristics, and the appropriate measuring instrument should be selected according to the situation in which it will be used.
1. Type C
Type C shore hardness testers use a glass tube with an inner diameter of approximately 6 mm and a scale. The hammer is a diamond indenter with a spherical tip and is approximately 20 mm long. The hammer falls down the glass tube and the height at which it bounces up can be read visually.
Compared to the D-type, the C-type shore hardness tester has a smaller hammer mass, and its hardness fluctuates less with the mass of the sample. However, reading must be done visually and requires experienced skill.
2. Type D
In the D-type shore hardness tester, a diamond indenter is attached to a cylindrical hammer made of steel. The hammer strikes the sample and bounces up, pushing the dial gauge spindle up, and the dial gauge pointer indicates the height of the hammer bounce.
Other Information on Shore Hardness Testers
Types of Hardness
1. Indentation Hardness
Hardness is measured by measuring the depth and size of a depression made when an indenter is pressed into a sample under a microscope. Rockwell hardness and Vickers hardness are typical examples.
2. Rebound Hardness
This is a quantitative definition of hardness based on the observation of the indentation formed in a sample when an indenter impacts the sample and the movement of the indenter after the rebound. Shore hardness corresponds to this rebound hardness.