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.
Conformal cooing channel of plastic injection mold
Feb 23, 2022The conformal cooling gate is a new type of mold cooling gate based on 3D printing technolog, because of its processing characteristics, the conformal cooling gate can fit the shape of the product...view
Venting system of plastic injection mold introduction
Feb 27, 2022Hello everyone, thanks for attention. We’ve discussed about the temperature control system earlier, now we are going to talk about the mold venting information in following 11 articles, from the...view
Hydraulic diameter conversion of runners in plastic mold gating system design
Jan 13, 2022Hydraulic diameter refers to 4 times the ratio of the flow cross-sectional area to the perimeter, as the wall shear stress of non-circular pipes is not even distributed along the surrounding walls,...view
Limitations of gas-assisted injection molding technology
Apr 25, 2022Gas-assisted injection molding technology has obvious advantages in thick wall thickness and pipe parts, but this technology still has many limitations, which are mainly reflected in the following...view
Slider angle designing tips
Dec 4, 20231. Normally, all the insertion slopes of the slider are not allowed to be less than 3° to prevent excessive self-locking force and scratched; 2. The angle of the locking surface must be bigger than...view
Plastic injection mold runner system design points
Jan 9, 2022When designing the gating system, Firstly, we should consider making the plastic melt fill the cavity with core side quickly to reduce pressure and heat loss; secondly, it should be economically...view