Difference between Low Pressure Injection Molding And High Pressure Injection Molding

Low pressure injection molding process has been widely used in industries because of its various advantages in these years. And it has replaced the traditional High Pressure Injection Molding process. What is the difference between high and low pressure injection molding process? We would like to introduce the difference between low-pressure injection molding and high-pressure injection molding process and the advantages of low-pressure injection molding.

What is is a high-pressure Injection Molding machine? In general, high speed, low pressure, or high pressure low speed, "pressure" refers to the system set injection pressure, "speed" refers to the system set injection speed. When the temperature rises, it is beneficial to the flow of material and generally needs to reduce the pressure and speed. Conversely, when the temperature is lower, the pressure and speed should be increased. Pressure and speed need to match, usually called low voltage, high speed or high voltage, low speed is relative. Speed has a great effect on the amount of heat produced by shearing, so the speed is equivalent to warming up to some extent. Typically, the temperature is controlled first to see if the melt is in good condition. Then, according to the cavity structure, adjust the pressure and speed, multi-level adjustment, in order to mold filling and good appearance. Generally speaking, products of low speed and high pressure ratio of the products of high speed small shrinkage.

Hot melt material and injection method are different. Materials used in low-pressure injection molding are different from the ones used in traditional injection molding machines. Viscosity of the hot melt adhesive used for low pressure injection molding is low and it fluids quickly after being hot melted. And it does not extruded by the screw. It can be made to flow by the gear pump as long as it is heated and melted by the glue cylinder, with a small pressure. It goes into the mold, the cool the mold. So, the low pressure injection molding machine does not have a screw device, and the glue is injected through the gear pump and the hose and the glue gun. This provides a good protection for fragile components.

 Heating pressure, temperature is different. Low-pressure injection molding is injection molding by preheating the hot melt adhesive. Low-pressure injection molding materials have good adhesive ability and are unmatched by traditional engineering plastics. The temperature of the low-pressure injection molding process is much lower than the traditional high-pressure injection molding, which reduce the precision instruments damages caused by high temperatures.

Temperatures for Low Pressure Injection Molding is low, cast aluminum mold can be used. Compared to steel mold, aluminum mold is better for design and development. And the development cycle of the mold is shorter. Also, compared to traditional high-pressure injection mold, low-pressure hot melt adhesive injection molding process cycle is shorter.