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.
Key points of plastic injection mold runner system
Jan 12, 2022The sub-runner is a transitional channel between the main runner and the gate, as the sub-runner is the longgest part of gating system, so it is very important to enhance the parts quality and improve...view
Well-ventilated steel of venting design for molded parts
Mar 14, 2022Well-ventilated steel is a sintered alloy, iIt is a porous material sintered with spherical particle alloys, the pore size is 7-10μm and the strength is poor, but the texture is loose which allow the...view
Comparison of water-assisted and gas-assisted injection molding
May 19, 2022Comparing with water-assisted injection molding technology and gas-assisted injection molding technology, the fundamental difference is the nature of the auxiliary molding media used. One is liquid...view
Factors affecting the cooling rate of parts by injection molding
Feb 9, 2022It should be shaped by cooling to get stable plastic part after plastic filling the cavity and core side, so most injection molds need to be equipped with cooling devices to make the mold temperature...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
The common fixing method of angle pin
May 10, 2024The angle pin is a common part of the drive slider, and the fixing and installation methods as following: 1. Pass through the mold plate directly and press the angle pin with the top plate to fix it,...view