1) The first step in the production process of plastic shells is to prepare materials. During the material preparation process, it is necessary to choose the quality of the plastic shell material and determine the type of material used. Because there are usually many choices of plastic shell materials, it is necessary to make precise choices.
2) After the second step of material selection is completed, the plastic shell production process goes to the mixing and drying process. The essence of mixing and drying is to remove moisture from the material and reduce the occurrence of defects in the plastic shell injection molding process. If the moisture in the material cannot be reduced by 0.02%, irregular silver lines will appear on the surface of the finished plastic shell, which has a significant impact on the appearance of the plastic shell.
3) The important production process for plastic shells in the third step is the injection molding process, which determines whether the plastic shell meets the standard. To produce a high-quality plastic shell, various factors such as temperature, mold, injection method, and injection speed must be controlled. Therefore, this process also needs to be carefully completed.
4) The fourth step is to complete the quality inspection of the plastic shell as the injection molding process is completed, and then the packaging is completed.
The process of making plastic shells
1) Extrusion molding
Extrusion molding, also known as extrusion molding in plastic processing, refers to a processing method in which materials are processed through the action between the extruder barrel and the screw, while being thermally plasticized and pushed forward by the screw, continuously passing through the machine head to produce various cross-sectional products or semi-finished products.
2) Injection molding
Thermoplastic injection molding, which involves melting plastic materials and injecting them into the membrane cavity. Once molten plastic enters the mold, it is cooled and formed into a corresponding shape according to the mold cavity sample.
3) Blow molding
Also known as hollow blow molding, a rapidly developing plastic processing method. The tubular plastic parison obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while it is hot (or heated to a softened state). After the mold is closed, compressed air is immediately introduced into the parison, causing the plastic parison to expand and tightly adhere to the inner wall of the mold. After cooling and demolding, various hollow products are obtained.
4) Blister molding
Vacuum forming, also known as suction molding, is a plastic processing process. The main principle is to heat and soften flat plastic hard sheets, then use vacuum to adsorb them on the surface of the mold, and cool them before forming. Mainly divided into two categories: thick sheet and thin sheet blistering
Precautions in the production of ABS plastic shell
1. ABS plastic has high moisture absorption and sensitivity. Before forming and processing, it must be thoroughly dried and preheated (at least 2 hours at 80-90C) to control the moisture content below 0.03%.
2. The melt viscosity of ABS resin is less sensitive to temperature (different from other amorphous resins). Although the injection temperature of ABS is slightly higher than that of PS, it cannot have a loose heating range like PS, and blind heating cannot be used to reduce its viscosity. Instead, increasing the screw speed or injection pressure can be used to improve its fluidity. The general processing temperature should be between 190-235 ℃.
3. The melting viscosity of ABS plastic is moderate and requires a higher injection pressure.
4. The use of medium to high injection speeds for ABS plastic has a good effect on beer production. (Unless the shape is complex and thin-walled parts require a higher injection speed), the product nozzle position is prone to air marks.
5. The molding temperature of ABS plastic is relatively high, and its mold temperature is generally adjusted between 25-70 ℃. When producing larger products, the temperature of the fixed mold (front mold) is generally slightly higher than that of the moving mold (rear mold) by about 5 ℃. (Mold temperature will affect the smoothness of plastic parts, and lower temperatures will result in lower smoothness)
6. ABS plastic should not stay in the high-temperature barrel for too long (should be less than 30 minutes), otherwise it may decompose and turn yellow.
