Chemical corrosion, the corroded metal material is iron. Common corrosive plastics include flame retardant plastics, acidic plastics, polyvinyl chloride plastics, etc. After the corrosion of screws, glue barrels, and flanges, some pits are formed on the surface, and the surface is rough, which increases the flow resistance of the melt during the operation of the injection molding machine. Some materials are prone to adhere to the surface, leading to decomposition and carbonization. When corrosion is severe, the gap between the screw and the glue barrel increases, the leakage increases, and the injection efficiency decreases. Whether it is flame-retardant plastics or acidic adhesives, plastics will decompose acidic gases during processing at high temperatures, and plastic melts are prone to carbonization and adhesion to metals. Therefore, on the one hand, plasticized components should adopt stainless steel or surface chrome plating schemes; On the other hand, in production and processing, low back pressure, low temperature, and low shear processes should be used as much as possible to reduce plastic degradation; Furthermore, due to the thermal sensitivity of the aforementioned plastics, high temperatures or prolonged heating times can easily lead to plastic decomposition, degradation, and carbonization. Therefore, it is important to avoid and reduce unnecessary downtime during the production process. If the machine needs to be shut down, it should be cooled down first, the material gate should be closed, and the molten material in the sol cylinder should be cleaned with PP or PS material before shutting down.
The groove in the feeding section of the injection molding machine screw is too shallow, which causes the screw to not be able to drive the plastic forward when rotating. It is also possible that the amount of material conveyed is very small and the design of the material barrel is the discharge port. Injection molding technicians:
1. It is necessary to strictly set parameters according to the material melting temperature;
2. After shutdown, the gun barrel must be cleaned according to regulations and the machine must be cleaned properly;
3. Check the stability of the adhesive injection endpoint daily.
Injection molding machine screw jumping and gap testing:
The gap between the end of the barrel and the screw should generally be as similar as possible using a feeler gauge. If the gap between the material barrel and the screw is poor, it is necessary to adjust the front, back, left, and right screws of seat 01 based on the overall machine level and nozzle center to obtain the gap. Screw jumping requires the use of a dial gauge and a magnetic base. After clamping the magnetic base with the dial gauge, the magnetic base is sucked onto the base, and the dial gauge head contacts the outer diameter of the screw tail. The dial gauge returns to zero, reducing the storage speed, and checking the jumping value of the dial gauge during storage.
