Car film glass is a common decoration method in car beauty and modification, but during the film process, heat treatment may cause changes in the size of the glass. In order to control and understand this change, it is necessary to measure the heating dimensional change rate. The following are the steps and procedures of the determination method:
Sample preparation:
According to specific requirements, the test is conducted under the environmental conditions of a temperature of 20â±5â, a relative humidity of 50% and 70%, and an atmospheric pressure of 8.6X10 4 Pa~1.06X10 5 Pa. Cut 120mm*120mm samples from the middle and edge of the film that has been left for 2 hours, a total of 3 pieces. When cutting edge samples, the distance from the edge of the film should be 50mm~60mm.
Test device:
Includes electric Forced Air Drying Oven, metal container (including kaolin bed), temperature measuring device and measuring tools. The electric Forced Air Drying Oven can control the temperature, circulate air and maintain the test temperature of the test group. The metal container can hold the sample flat and can be placed in a Drying Oven.
Test procedure:
a) Mark and measure the initial length in the longitudinal direction of the film on the sample;
b) Place the sample flat on the kaolin bed in the metal container and cover it with a thin layer of kaolin;
c) Place the container into a Forced Air Drying Oven, raise the temperature to 160°C and keep it for 30 minutes;
d) After heating, take out the sample, place it under the specified conditions for at least 30 minutes, and measure the length between the marks again.
Result expression:
Calculate the shrinkage of the film according to the given calculation formula, the formula is as follows:
â³L = (L0 - L) / L0 * 100%
In the formula, â³L is the shrinkage rate of the film; L is the value of the length between marks after heating, in millimeters; L0 is the value of the initial length between marks, in millimeters.
Through the above measurement methods, the dimensional changes of automobile film glass after heat treatment can be accurately evaluated, providing reliable data support for the film application process.
