With the rapid development of the transportation network, the demand for passenger cars is increasing, and the requirements for the safety and comfort of passenger cars are also increasing.

Beautiful and luxurious interiors have become one of the important symbols of luxury passenger cars. Interior decoration mainly refers to plastic parts, and its molding processes include injection molding, blister molding, blow molding, extrusion, etc. Injection molding has high production efficiency and high precision of molded products, but it molds complex parts, but the mold cost is high, the product update is slow, and the part size is limited by the machine specifications. Therefore, the injection molding application of passenger cars is mainly complex parts such as dashboards and air-conditioning vents, which require precisely matched parts.

The investment cost of blister molding molds is small, suitable for the production of large-size parts, and suitable for rapid product replacement, but the dimensional accuracy is not high and the production efficiency is low. Mainly covering parts, because the interior of large buses is not accurate, and the output of buses themselves is not high, generally about a few hundred models, plus customers often put forward various requirements for the interior configuration of automobiles, the changes in part size and appearance are more or less, so there are more blister molding processes in bus interiors. Blow molding and extrusion molding are both plastic parts with specific requirements, and they are less used in the field of bus interiors. According to the process, the blister molding can be divided into sheet blister molding and soft skin blister molding. The blister materials are mainly acrylonitrile-butadiene-styrene (ABS) plates, and a small number of parts are made of organic glass (PMMA) plates. ABS plates are used for inner plates, top inner plates, rear inner plates, and some electrical box covers, etc., which are left and right covers of the passenger car cab. There is still a trend to replace ordinary ABS plates with composite ABS plates. Composite ABS plates are made of polypropylene or polyvinyl chloride materials with a foaming layer on the plate, and the plates with pressed leather grain or leather-like feel are rolled together. The requirements are a three-dimensional cover plate of a transparent instrument panel, and the requirements are an anti-aging fuselage with a breathable grille on the outside. Organic glass molding is commonly used. The soft skin blister process is mainly used on the bus instrument panel. The base is generally made of fiberglass, and the water absorption holes are opened on the fiberglass surface. The skin is mainly made of polyvinyl chloride and foamed polypropylene (PVC/PPF) composite materials.

Now take the inner plate of a passenger car as an example to illustrate the blister process. The size of the part is 1200mm×1000mm×250mm, and the ABS board used is 1400mm×1200mm×4mm. First, confirm the color of the board leather grain, because the color of the interior and leather grain is very important, and the passengers first feel the environment in the car. See if the board in the packaging bag has just been opened. If not, the board needs to be placed in the drying room for drying. Because if the plate is wet, the surface of the plate will bubble during heating, the appearance quality will deteriorate, and in severe cases, the plate will be in the molding process. At the same time, the plasticizer is installed on the mold, the position and pressure frame are adjusted, and the rising process and time of the mold are pre-set; the top of the mold should not exceed the working platform of the plasticizer, and then the mold is heated to about 60°C. On the automatic feeding device, the machine puts the board on the workbench of the blister machine (if there is no such mechanism, the board will be manually placed on the workbench), and the pressing frame presses the board from top to bottom. Then the heating mechanism moves to the upper part of the table to heat the plate, generally heating to about 120°C for 2~3 minutes. If it is advanced equipment, you can also set the regional temperature of the heater, and increase the heating temperature in the stretching place. After heating, remove the heating mechanism and the mold starts to move upward. In order to prevent the mold from contacting the sheet too early during the rising process and leaving marks on the parts, the mold contacts the sheet before it rises, blows air from the mold suction hole, and blows up the sheet. The mold continues to rise, rises to the desired position, stops rising, and starts to inhale. The suction pressure is generally 0.6~0.9 atmospheres, depending on the thickness and performance of the sheet. The suction time is very fast, generally a few seconds, and then cools for 2 minutes. During the cooling process, the negative pressure of the vacuum box should not drop too much to avoid the rebound of the board and inaccurate size. It is best that the negative pressure drop does not exceed 20% of the suction volume. The cooling method is air cooling, and some water spray cooling is also used to improve production efficiency. After cooling, demolding, automatic plasticizer is demolding, away from the workpiece, and there are certain requirements for the demolding slope, otherwise the demolding will not be smooth and the parts will be broken. Then you go up and take the parts out. At this point, the vacuum forming process is completed. However, for complete parts, it is still necessary to form the workpiece trimming and assembly processing. The trimming can be done manually or by 3D CNC milling. The application of blister molding in passenger cars is becoming more and more mature.