English
русский
The difference between full shot and short shot of gas-assisted injection molding
Gas-assisted injection molding can be divided into short shot and full shot.
- Short shot
The short shot method is shown in picture 1, it is suitable for thick-walled plastic parts with low mold filling resistance, especially rod-shaped parts, which can save a lot of raw material, we should inject part of resin into the cavity and core (usually only fills 50% volume of caity and core) during the short shot, and immediately inject gas into the center of the resin, push the gas and obtain a hollow plastic part, For thin-walled plastic parts with high mold filling resistance, it’s better to use full shot molding.
For short shots, the percentage and prolong time of plastic melt fills the cavity and core before the gas injected are the main factors to control the length of the gate channel, in addition, the further shrinkage of the plastic will make the channel continue to be longer, if too much plastic is injected at early stage, it will cause the gas flow length is not enough, but if too little plastic is injected, the gas will quickly penetrate the plastic flow front and cause waste.
2. Sub-cavity method (full shot)
The secondary cavity molding method, it is also called the overflow well method, it is a kind of full shot process (as shown in picture 2). the secondary cavity method requires a secondary cavity that can connect with the mold cavity in outside, the secondary cavity follows the main cavity, the valve needle between the cavities is opened or closed by the hydraulic cylinder or air cylinder, first, close the sub cavity, inject plastic melt into the cavity until the cavity and core is full, then open the sub cavity, and inject gas into the cavity, the penetration of gas pressure causes the excess melt to flow into the secondary cavity, when the gas penetrates to a certain extent, the secondary cavity is closed, and the gas pressure continues to increase to maintain pressure and feed the melt in the cavity with core side, and finally open the mold to eject products.
The principle of mold temperature balance in plastic mold cooling system design
Feb 21, 2022The principle of mold temperature balance: 1. Due to the complexity of the plastic parts and mold structure, it is difficult to make the temperature of the mold completely consistent, but should be...view
The sub gate of the plastic injection mold runner system
Jan 26, 2022In order to get the best injection quality, the gate type must be selected carefully, the coommon gate tyeps are: direct gate, side gate, pin-point gate, sub gate,valve gate of hot runner etc. Among...view_20250317090912A017.jpg)
Several common process of water-assisted injection molding introduction
May 24, 2022According to the design of the injection molding machine and the casting system, the corresponding melt-returning process of water-assisted injection molding can be roughly divided into two types: the...view
Direct gate of plastic injection mold runner system design
Jan 19, 2022In order to get the best injection quality, the gate type must be selected carefully, the coommon gate tyeps are: direct gate, side gate, pin-point gate, sub gate,valve gate of hot runner etc. Among...view
Water assisted injection molding introduction
May 11, 2022Like the gas-assisted injection molding process, water-assisted injection molding injects a piece of plastic into the mold cavity and core firstly, and then injects water to squeeze the melt plastic...view
Design principles of plastic injection mold runner system
Jan 6, 20221. Quality first The design of the gating system has a big influence on part quality, firstly the gate should be set at the easiest part of the plastic part to be removed, and at the same time, the...view