1. Principle and method of pendulum rod damping test

GB/T 1730 standard specifies the determination method of the hardness of the paint film, based on the principle of pendulum rod damping. This method uses a pendulum rod, which swings in a certain period, and evaluates the hardness of the paint film by the decay time of the swing. Specifically, two steel balls are embedded under the pendulum rod, which contact the paint film template, and the fixed mass of the pendulum rod exerts pressure on the paint film when it swings, thus causing the paint film to produce resistance. The hardness of the paint film is positively correlated with the swing decay time, that is, the longer the decay time, the higher the hardness of the paint film.

The standard also describes two test methods: method A and method B. Method A adopts Koenig or Persasz two kinds of pendulum rod damping tester, commonly known as single pendulum test. B rule using paint film pendulum hardness tester, commonly known as double pendulum tester. These two methods have their own advantages in different application scenarios, and suitable methods can be selected for film hardness testing according to specific needs.

Pendulum damping test method for determination of hardness of paint film  introduction

2. Operation points and precautions

In the pendulum rod damping test, the following operating points and precautions need to be paid attention to:

Standard glass panels should be wiped clean with alcohol before use to ensure a clean surface.

The steel ball needs to be inspected regularly, and if the surface is worn or rusted, it should be cleaned or replaced.

The operation process must be careful, especially when swinging the pendulum, it should be carefully operated to prevent a slight movement of the pendulum from affecting the test results.

In addition, the hardness of the film is affected by many factors, including film thickness, temperature, humidity, air flow and the appearance of the template. The thicker the film, the lower the hardness value, because the increase in the thickness of the film will lead to an increase in friction resistance. High temperature will soften the paint film, high humidity will make the paint film hard, these factors will affect the test results. In addition, the poor condition of the air flow and the appearance of the template will also increase the friction resistance, which will reduce the hardness value. Therefore, it is necessary to control these influencing factors to ensure the accuracy and repeatability of the test results when conducting the pendulum bar damping test.

Pendulum damping test method for determination of hardness of paint film  introduction

3. Result presentation and instrument calibration

The representation of film hardness depends on the test method used. In the double pendulum test, the film hardness value is expressed as the ratio of the swing decay time to the amplitude swing decay time on a standard glass plate. In the single pendulum test, the hardness value of the paint film is expressed by the oscillating decay time. It should be noted that in the actual test, multiple measurements should be carried out and the average value should be taken to reduce the error.

In addition, the calibration of the instrument is one of the key factors to ensure the accuracy of the test. The calibration requirements of the double pendulum hardness tester and Koenig hardness tester are specified in the standard to ensure the reliability of the test results.

Pendulum damping test method for determination of hardness of paint film  introduction

4. Application fields and importance

The pendulum rod damping test by film hardness determination is widely used in coating industry. It can be used to assess the hardness of different types of coatings, including paints, coatings, finishes and coatings. During the coating process, the hardness of the coating is crucial to the wear resistance, durability and protection of the coating. Therefore, through the film hardness test, it can provide paint manufacturers with key quality control data to help them improve product formulation and production process.

In addition, film hardness testing also plays an important role in quality control and maintenance after painting. For example, in the automotive industry, paint film hardness testing is used to assess the durability and appearance quality of body surfaces. In the construction industry, film hardness testing is used to check the quality and weather resistance of painted surfaces. In addition, this test method can also be used to study the properties of different coating materials to meet the needs of specific applications.

conclusion

The pendulum bar damping test in GB/T 1730 standard is a reliable method for evaluating the hardness and properties of coatings. By carefully following the operating points and precautions, as well as the calibration of the instrument, the accuracy and repeatability of the test results can be ensured. This test method has a wide range of applications in the coatings industry and is essential for quality control and product improvement for coating manufacturers and application areas. Therefore, understanding and mastering the pendulum rod damping test is one of the important tasks for practitioners in the paint industry, which helps to improve the quality and reliability of paint products.