Reasons for gas in the manufacture of products
1. The material in the feeding system has gas or there is air in the cavity, and the gas in the runner and cavity is not discharged in time during the molding process.
2. Insufficient drying of resin, which contains water and becomes water vapor by evaporation at injection temperature.
3. The injection temperature is high, and the plastic decomposes and produces gas.
4. Some additives in the resin, volatile or chemical reaction to generate gas (such as thermosetting plastic molding, not only the plastic itself contains water and volatile components, but also in the curing process condensation reaction, resulting in condensation of water and low-molecular volatile gas).
5. residual gas in the resin.
Consequences of poor mold exhaust.
1. the gas is subjected to large compression and generates backpressure, and this back pressure increases the resistance of the molten material to the flow of the mold filling, preventing the molten plastic from filling the mold normally and quickly, so that the mold cavity cannot be filled, resulting in unclear plastic edges.
2. The products show obvious flow marks and fusion seams, and the mechanical properties of the products are reduced.
3. After the gas is compressed, it will penetrate into the inner layer of the plastic, causing the plastic to produce silver lines, pores, loose tissue, peeling, and other surface quality defects.
4. The gas in the cavity will be compressed and generate heat to make the local temperature of plastic rise, and the plastic melt will be decomposed and discolored and even scorched and carbonized.
5. poor exhaust, reduce the filling speed, increase the cycle time of forming the parts (especially
high-speed injection molding), seriously affects productivity.
Latest blog posts
Custom molds injection molding
Custom molds injection molding is a manufacturing process that involves creating custom molds to produce plastic parts. Injection molding is a popular technique used in various industries such as...
Plastic injection molding companies
Plastic injection molding is a manufacturing process that involves injecting molten plastic into a mold to create a wide range of plastic products. From car parts to medical devices and household items, plastic injection molding is used to create a variet
PET Preform Injection Moulding Machine
PET preform injection molding is a manufacturing process that is used to create PET (polyethylene terephthalate) preforms that can be later blown into bottles, jars, and other containers. This process...
You may like
Several aspects that need attention to reduce the degree of wear of injection molding machine screw
Several aspects that need attention to reduce the degree of wear of injection molding machine screw, Injection molding machine screw for a long time in high temperature, high pressure...
A plastic cup mold assembly and mold making method
1. The present utility model relates to the technical field of moulds, specifically a plastic cup mould assembly and mould.
How to determine plastic pressure drop in injection molding
As the plastic flows through the injection molding machine and different parts of the mold, there is a loss of pressure acting on the plastic flow front due to resistance and friction. In addition...
Solution for bad exhaust of injection molded parts
Failure analysis and troubleshooting methods,1. Improper equipment selection,In the selection of equipment, the maximum injection volume of the injection molding machine must be greater than the total weight...