Experimental Study On Thermoformability Of IMD Film

In-Mould Decoration is a kind of surface decoration technology, IMD for short, which is a manufacturing process where a plastic film is heated to a pliable forming temperature, formed to a specific shape in a mold, trimmed to create a usable product, and injection molded. Thermoform is one of the key techniques of IMD, in order to improve the forming height and quality of IMD product, it is needed to study the thermalformability properties of IMD film.IMD film materials are mainly subjected to biaxial tensile stress in the process of Thermoform, and the research on Thermoform for IMD film is based on single tensile test so far. There are some differences in the deformation of the material under two kinds of drawing. This paper is to do the biaxial tension test to simulate Thermoform, and study the Thermoform process under different temperature and speed. The main work and achievements of this paper are as follows:(1) By analyzing the stress of the film material during the process of thermoform, In this paper, a method of simulating the IMD film thermoform by means of the biaxial stretch experiment method is constructed.(2) The biaxial tension experiment of PET film materials used in IMD thermoform process was used to analyze the effect of temperature on the thermoformability. The experimental results show that the stress level of PET film is gradually reduced with the increase of temperature, and at the 150 degree, the forming height is the largest and the rebound rate is the lowest.(3) The biaxial tension experiment of PET film was used to analyze the effect of thermoform speed on the thermoformability. The experimental results show that the stress level of PET film is gradually reduced with the increase of thermoform speed, and when the speed is 50mm/min, the forming height is the largest.(4) Through the comparison of biaxial stretch experiment and single tensile test, the following conclusions are obtained: The elastic modulus and yield strength of the single tensile test have a certain correspondence with the data obtained by biaxial tensile experiment, but there is a big difference between the elongation and the rebound rate. Therefore, the biaxial stretch experiment can be better for IMD film thermal forming performance analysis and research.