Key points of blister processing

The main principle of the blister processing technology is to heat the flat plastic hard sheet to become soft, then adsorb it on the surface of the mold by vacuum, and then form it after cooling. The main points of the blister processing process include the draft slope, the influence of the aspect ratio on the blister, the molding area and the product area, the exhaust surface, the exhaust hole, the exhaust groove, and the shrinkage deformation of the blister molding.

Blister release slope

In order to be able to release the mold smoothly, the side of the mold must have a certain inclination. In the demolding direction, the inclination of the side of the mold is called the demolding slope. The demolding slope should be as large as possible. The larger the demoulding slope, the faster the demoulding, the shorter the molding cycle, and the possibility of product deformation during the demolding process is small, and the demolding slope is generally greater than 1 degree. After years of experimentation and research and development, Jiangzhiyuan Company has broken through the technical difficulties of blistering with O-degree demoulding, and has opened up a new direction for the application of blister products.

The ratio of die width to depth is often referred to as the aspect ratio. Generally speaking, because the punch can drag and pre-stretch the sheet, the aspect ratio when forming with punch can be smaller, but not less than 1. The aspect ratio for die molding is usually not less than 1.4.

Blister forming area and blister product area

The molding area refers to the length and width of the inside of the clamping frame; the product area refers to the area where traction and stretching occur during the molding process, which mainly depends on the size of the blister product. During the heating process, the stretching part needs to be heated, the stretching range is larger, and the stretching amount is also less for the non-product area with less heating amount. It should be noted that the uneven heating will also cause the problem of uneven shrinkage after molding and cooling, which will deform the blister product.

Exhaust surface, exhaust hole, exhaust groove

In the process of vacuum forming, a sealed space is formed between the heated film and the mold. In the case of vacuum pumping, the remaining air in the closed space needs to be evacuated, and corresponding exhaust holes and exhaust must be designed in the mold. groove. The size of the exhaust hole After ensuring the function of exhaust, please try to design a smaller hole diameter, otherwise it will leave obvious pores on the surface of the product and affect the appearance.

The air can be quickly discharged by the vacuum suction device. Therefore, during the blister process, it is necessary to ensure that the vacuum system of the blister equipment can maintain sufficient vacuum to ensure that after the film is heated and softened, there can be enough vacuum suction so that the film can be It is completely adhered to the surface of the mold; on the other hand, it is necessary to keep the channel system such as the exhaust hole and the exhaust groove in an unobstructed state, so as to avoid the reduction of the vacuum degree caused by the blockage of foreign objects, resulting in insufficient plastic forming.

Shrinkage deformation of blister molding

In the process of blister production, product shrinkage and deformation often occur, and special treatment is required for different situations. After heating and forming, the mold is shaped and the vacuum is maintained in the cooling stage, so that the size of the blister product will not change too much, but due to the temperature change after demolding, the size will shrink and deform to a certain extent, and it will The shrinkage deformation will be greater with the increase of time. After 24 hours of molding, the shrinkage is basically stable, and the measured size is more accurate at this time.

Post time: Apr-15-2022

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