GB/T 39693.8-2022 in English

GB/T39693.8-2022/ISO488:2018 standard interpretation

This standard is part 8 of GB/T39693 "Determination of hardness of vulcanized rubber or thermoplastic rubber", which mainly specifies the method of determining the apparent hardness of rubber rollers by the Zhao's hardness (P&J) method. This method determines the hardness value by measuring the depth of the indentation formed by the indenter pressing into the rubber surface under the rated pressure.

Background of standard formulation

GB/T39693.8-2022/ISO488:2018 is equivalent to the international standard ISO488:2018, aiming to unify the specifications for the determination of hardness of vulcanized rubber and thermoplastic rubber. This standard fills the gap in the field of Zhao's hardness (P&J) method in China and provides a unified technical basis for the rubber roller industry.

Technology Evolution Analysis

Hardness is an important performance index of rubber materials, which directly affects its application field. Traditional hardness measurement methods (such as Shore hardness) are mainly suitable for thin sheets or small samples, but have limitations for the apparent hardness measurement of large rubber rollers. The Zhao hardness (P&J) method can more accurately reflect the mechanical properties of the rubber roller surface through reverse measurement.

Instrument composition and working principle

The Zhao hardness tester consists of a hardness tester bracket, a indenter (including steel ball and depth gauge), a load weight and a sample fixture. Its working principle is as follows:

• The indenter is composed of a polished carbide steel ball with a diameter of 3.175mm to ensure the consistency of the indentation shape.
• After applying a rated load of 1000g±2g, the depth of indenter movement is measured.
• Record the indentation value using a micrometer or a depth gauge with a graduation value of 0.01mm.

Comparison of standard frameworks

Actual application case

Implementation suggestions

1. It is recommended that companies establish a dedicated hardness testing laboratory to ensure that temperature and humidity control meet the requirements of ISO23529.
2. Regularly calibrate the hardness tester and its accessories (such as steel balls, depth gauges, etc.), refer to the calibration frequency specified in Table A.1.
3. During the production process, it is recommended to conduct hardness sampling inspections on each batch of products and record relevant data for traceability.