Gas-assisted injection molding car handle
Gas-assisted injection molding car handle，also known as gas injection (shot) plastic is a new injection molding process. It is 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.
Gas-assisted injection molding equipment
(1) Ordinary injection molding machine (the metering accuracy is slightly higher).
(2) Nitrogen control system, including self-sealing gas-assisted nozzles.
(3) High pressure nitrogen generator.
(4) Industrial nitrogen cylinders and air compressors that provide supercharged power.
(5) A mold designed and manufactured for gas-assisted injection.
(6) Gas-assisted injection molding gas auxiliary nozzle
As one of the most effective ways to reduce the wall thickness of plastic parts, gas-assisted injection molding also reduces the necessary cooling time, reduces material consumption, and eliminates the need for complicated mechanisms in the mold.
This process seems simple, but for the best results, it requires high-precision process control:
◆ The first step is to completely fill the cavity and solidify the outer layer by cooling the cavity wall.
◆ Then, the controlled dose of nitrogen is blown into the plastic melt through the injection nozzle at a pressure of up to 300 bar, where the pressurized gas acts like a piston, allowing the still molten plastic melt to pass through The mechanically open channel is moved from the core area into the overflow chamber.
Depending on the type of door handle, the amount of plastic melt that is pushed out is approximately 25% to 30% of the total.
The air pressure inside the hollow part then counteracts the shrinkage caused by the cooling, thereby eliminating potential sink marks on the outer surface.
At the end of the cooling, the contents of the molded part and the overflow chamber are taken out. The contents of the overflow chamber are cut and recovered for reuse with the native material.
According to the type of door handle, the cycle time is shortened by approximately 45 to 50 s, so it is roughly equivalent to the production cycle time with the slider.