Shore hardness scores are mechanical and digital explicit

Type A is suitable for general rubber, synthetic rubber, soft rubber, multi-fat, leather, wax and so on

Type C is suitable for microporous materials made of rubber and plastic containing foaming agent

Type D is suitable for general hard rubber, resin, acrylic, glass, thermoplastic rubber, printing board, fiber, etc.

Calibration of Shore hardness tester

The force of Shore hardness tester was calibrated with a balance. Fix the durometer vertically, press against a tray of the quasi-balance, and place a small pad in the middle of the tray to avoid contact between the press foot and the tray, as shown in the picture. There is a small cylinder on the mat, about 2.5mm high and 1.25mm in diameter.

For the calibration of type A hardness tester, the upper end of the cylinder is slightly concave in the middle to accommodate the pressure needle resting on it; For the calibration of d-type hardness tester, the middle of the upper end of the cylinder should have a small hole with a diameter of about 0.5mm, so that the needle can enter the small hole, the hole has enough depth, so that the spherical surface on the top of the needle does not contact the bottom of the hole.

The weight of the small pad in the balance of another tray with weight balance, and then continue to place weight on the tray, so that the pressure needle is subjected to vertical upward force, change the quality of the broken code, the force on the pressure needle changes accordingly, hardness tester get different values.

The relationship between the force and the value is given, the allowable deviation of the force calculation results of type A hardness tester is ±80mN, and that of type D hardness tester is ±440mN.

It can also be calibrated with an electronic balance of corresponding accuracy or other force measuring instruments specially designed for Shore hardness tester. For the calibration of scales or other force measuring instruments for Shaw type A durometer, the error shall not exceed ±8.0mN, for the calibration of Type D durometer, the error shall not exceed ±44.0mN.

Structure of Shao type hardness tester

Press foot: there is a round hole with a diameter of 2.5mm to 3.2mm in the middle of the press foot, and the hole center is at least 6mm away from the edge of the press foot.

Pressure needle: pressure needle is made of hard steel rod with diameter of 1.25mm±0.15mm

The tip diameter of type A is 0.79mm,

The tip diameter of type D is 0.2mm, that is, the radius is R0.1.

The measuring needle of type C is a ball 5mm in diameter.

Indicator mechanism: used to read the extension of the pressure needle relative to the foot surface.

Use of Shore hardness tester

Place the sample on a solid plane, hold the durometer, and press the pressure foot on the sample at least 12mm from the edge of the sample smoothly, so that the pressure needle is pressed vertically into the sample, until the foot and the sample are in full contact with the reading within 1s. The hardness values were measured 5 times at different locations with measuring points at least 6mm apart, and the average value was taken (the measuring points of microporous materials were at least 15mm apart). In order to stabilize the testing conditions and improve the testing accuracy, the hardness tester should be installed on the same type of testing rack.

Application of Shore hardness tester

Type A Shore hardness tester is used to measure the hardness of soft plastics, rubber, synthetic rubber, felt, leather and printing cots. Type C Shore hardness tester is used to measure soft materials such as foam materials and sponges. D-type Shore hardness tester is used to measure hardness of hard plastics and rubbers, such as thermoplastics, hard resins, flooring materials, bowling balls, etc. It is especially suitable for in-situ hardness measurement of rubber and plastic finished products.