English
русский
The main reasons for air trapping of plastic injecton mold
During the injection molding process, the front end of the slight ribs may be air trapped and plastic burnt, and also cause the molded part may become black and carbonized.
The mechanism of air trapped scorching is that when the air in the mold cavity is extruded by the molten plastic flowing into the cavity, the air will heat due to being compressed if it is in a sealing state without an outlet, and then it leads to combustion and burns.
Since the air is a kind of gas, it can be compressed, but it generates heat when compressed, it is like when we use a pump to inflate our bike tires, the pump gets hot.
The compression of the residual air in the cavity usually occurs in a short time of about 0.1 to 0.5 seconds, because it is compressed under a high pressure of 200 to 500 kgf per square centimeter, it is easy to heat up to the ignition point of the plastic (as shown in picture 1).
Therefore, for some slight ribs, pillars and other product features in the gas injection mold, it is necessary to make venting slot to let the gas in the mold which can be discharged to the outside of the cavity.
Plastic injection mold runner system design
Jan 16, 2022The gate is the connecting part between the runner and the cavity, and is also the end part of the injection mold gating system, the molten plastic enters the cavity and core side through the gate...view
Gate position determination of plastic injection mold runner design system
Jan 17, 2022In the selection of gate location, the following issues should be paid attention to: 1. The gate position should be set at the maximum wall thickness of the plastic part, so that the plastic melt...view
Plastic cooling factors by injection parameter
Feb 10, 20221. Plastic parts design: mainly for the wall thickness of plastic products. The thicker thickness of the product, the longer the cooling time. Generally speaking, the cooling time is approximately...view
Slider designing tips 1
Aug 3, 20221. After the slider core pulls out, the length of staying in the guide pin slot should not be less than 2/3 of the total length of the slider, for special cases, the slider slot can be partially...view
The air trapping position in cavity and exhaust method
Mar 2, 2022The air trapping in cavity is usually in the following places: 1. Thin-wall structure cavity, the end of melt flow; 2. The junction of two or more melts; 3. The last area where the melt in the cavity...view
Plastic injection mold heating
Feb 16, 2022When the plastic injection molding process requires the mold temperature to be above 80°C, a temperature adjustment system with heating function must be provided in the mold. In addition,...view