Under the effect of high temperatures, the structural characteristics of non-metallic materials, insulation materials will change greatly, which manifests itself softened or melted. Ball pressure test is used to test the heat resistance of non-metallic materials and insulating materials. It indicates the requirements of the ball pressure test in IEC60695, UL, IEC884-1, GB / T5169.21-2006, GB4706.1-2005 and GB2099.1-2008 and other standards.
During the test, to make the test results more accurate to the actual heat resistance of sample, we need to pay attention to the requirements of test temperature of the heating chamber, ball pressure tester, test samples and the indentation test and other measurement.
Test temperature is one of the most important conditions in the ball pressure test. It directly affects the size of the indentation that on the test samples. The test temperature is controlled by heating chamber. It requires the accuracy of temperature is ℃ in the ball pressure test standards. Generally, the indicated temperature of heating chamber is different from the actual temperature inside the chamber. Thus, in practical tests, we use a thermocouple to monitor the actual temperature inside the tank, especially near the test sample. It can also use a curve to reflect the actual temperature near the test sample if conditions permitted.
Monitoring the temperature of heating chamber by curve, the benefit is that it can reflect the changes of temperature near the sample inside heating chamber. According to the standard, it is possible as long as the fluctuation amplitude is not exceeded ℃. To achieve this standard, we should shorten the time of chamber opening, to make the temperature drop as small as possible, while also reducing the rising temperature after reached the test temperature. In order to reduce the rising temperature during the test, we can set the temperature as test standards after closed the chamber. After buffered twice like this, it can make the rising temperature more placid, and make the temperature of the heating chamber more closely to test temperature.
IEC60695-10-2: 2003 standard indicates that the heating chamber and the sample holder shall be kept for 24 hours or until thermal equilibrium under the test temperature, which can reduce the impact of the holder on the test results. If the sample holder and the sample simultaneously put into the chamber after thermal equilibrium, the sample holder needs to absorb a large amount of heat to reach the temperature of the heating chamber, which extends the time of heating chamber equilibrating next time, and reduces the test time of samples under the test temperature, which would directly reduce the test conditions.
In the ball pressure apparatus, pressure ball is a complete ball of diameter 5mm, and weights press on the test sample through the ball. The pressure ball can be a whole ball, half ball, less than half ball or more than half ball. The test load device consists of pressure ball and weights. According to standards, the weight of the load is 20N ± 0.5N, the diameter of pressure ball is 5mm. Besides these requirements, we need to pay attention to the following comments:
A. The surface of the pressure ball must be smooth, wear pressure ball will affect the force that exerted by load on the surface of samples, which lead to bias of the test results;
B. Sample holder should firmly supports the test sample in a horizontal state;
C. Sample holder should have sufficient strength to support the load device;
D. During the installation and removal of test samples from the heating chamber, the sample holder should have enough mass to prevent the temperature of the test apparatus from significantly reducing;
E. The surface of sample holder should be smooth.
Lisun’s ZBP-T Ball Pressure Test Device fully complies with IEC60695, UL, IEC884-1, GB/T5169.21-2006, GB4706.1-2005 and GB2099.1-2008 standards. Lisun Group leads in CFL & LED Test Instruments, Environmental Testing Chamber, EMI/EMC Test Equipment and Electrical Safety Testing. All Lisun products quality system has been strictly certified by ISO9001:2008. The Lisun Group products have been authenticated by the third party lab and were awarded by CE certificate. As a CIE Supportive Membership, all of the test instruments produced by Lisun Group were designed according to CIE Standards.