One of the most important developments in the injection […]
One of the most important developments in the injection molding industry since the advent of reciprocating screw injection machines. Gas-assisted injection molding is an extension of injection molding. It is developed on the basis of injection molding technology and structural foam injection molding. It can also be considered as a certain compounding of injection molding and hollow molding. In this sense, it can also be called "Hollow injection molding". The principle is to replace the resin in the cavity with a relatively low pressure gas during the pressure holding stage of the original injection molding. Gas-assisted injection molding can be realized by adding a gas supply device to the existing injection molding machine. The gas supply device is composed of an air pump, a high pressure gas generating device, a gas control device, and a gas nozzle. The gas control unit is continuously supplied with a special compressor, and is controlled by an electric control valve to keep the pressure constant. The pressure usually has 3 levels. A gas control unit can be equipped with multiple injection molding machines
Gas-assisted injection molding technology features
(1) The design of the mold cavity should ensure the flow balance to reduce the uneven penetration of the gas, and ensure the flow balance is also a design principle of the common injection molding mold, but this is more important for the gas-assisted injection molding products.
(2) The mold design should consider the influence on the process parameters, because gas-assisted injection molding is much more sensitive to process parameters than ordinary molding. In injection molding, small differences in mold wall temperature or injection volume can lead to asymmetry of gas penetration in symmetrical parts.