Gas assisted injection molding has advantages such as low injection pressure, small warping deformation of finished products, good surface quality, and easy processing of products with significant wall thickness differences. It has been rapidly developed in recent years. It has been used for commercial production of plastic products in developed countries for over 20 years.
Gas assisted injection molding includes injection molding of plastic melt and injection molding of gas (usually using nitrogen).
Compared with traditional injection molding skills, gas assisted injection molding requires more skill parameter determination and control, so there are special requirements for product planning, mold planning, and molding process control.
The process of gas assisted injection molding first involves injecting insufficient resin into the mold cavity, and then introducing high-pressure compressed nitrogen gas into the edge of the molten material. The gas flows along the direction of minimum resistance to the low-pressure and high-temperature areas of the finished product.
When gas moves in the finished product, it empties the thick walled section by replacing the molten material, and these replaced materials fill the rest of the finished product.
After the filling process is completed, the gas is continuously supplied to maintain pressure, minimizing the problem of shortening or warping of the ejected product.
Advantages of Gas Assisted Injection Molding
Low injection pressure reduces residual stress and then minimizes warping deformation;
Low injection pressure reduces the demand for clamping force, and small tonnage machines can be used;
The low residual stress also improves the size and stability of the finished product;
Low injection pressure can reduce or eliminate the appearance of finished product burrs;
The finished meat is thick and some are hollow, and then the plastic is reduced to a maximum of 40%;
Compared with solid finished products, the molding cycle is shortened, less than half of that of foam molding;
Gas assisted injection molding significantly improves structural integrity and planning freedom;
For some finished products with significant differences in wall thickness, gas assisted techniques can be used to form them in one go;
Reduced the pressure inside the mold cavity, reduced the loss of the mold, and improved its operational lifespan;
Reducing the injection point, the airway can replace the warm runner system and reduce the cost of the mold;
Stiffness has been added to the gas channels along the rib plate and the root of the protrusion, eliminating the need for concerns about shrinkage marks;
Excellent surface smoothness, no need to worry about the swirling effect caused by foam forming.
After using gas assisted injection molding skills, the planner agreed to make the product planning more chaotic, while the mold manufacturer could simplify the mold structure.
The continuous addition of finished product functions and the reduction of finished product components shorten the production cycle, eliminating the need for installation and post-processing operations.
Gas assisted injection molding has been shown to be suitable for the production of thin-walled finished products in the production of CD pallets and automotive electronic center laminated boards.
The improvement of dimensional stability, reduction of residual stress in finished products, and reduction of warpage are the primary strengths of gas assisted injection molding skills.
The use of gas assisted injection molding skills will become increasingly complex and diverse.
Nowadays, gas assisted injection molding techniques can be used to produce finished products with a mass ranging from 30g to 18kg.
Article organization: Heshan Pearl Cotton
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