Broken down to its most fundamental components, an injection molding machine, or press, is comprised of three functional units: 1) injection (which melts and transmits the plastic granules), 2) mold (the custom designed portion which produces a specialized product,) and 3) clamping (which provides the controlled pressure to open and close the mold.
The first injection molding machine was patented in 1872 by this American inventor. High need for plastics led to the discovery of a Screw Injection molding Machine.
A mold is bolted into the Clamping section of the machine. The injection molding machine closes the mold, then applies a large force to “Lock” the mold closed. Inside the closed mold is a cavity that is the exact shape of the plastic part.
The Injection section of the machine has a hopper to hold plastic pellets; a barrel with heater bands to liquefy the plastic pellets; a feed screw to move the pellets forward in the barrel; a check valve to force the liquid plastic into the mold, and a nozzle to seal the injection section to the mold. The liquefied plastic is forced into the cavity of the mold with high pressure.
Once the liquid plastic has been injected into the mold, theinjection molding machine goes into the Cooling phase. The liquid plastic must cool enough to turn solid so it takes on the shape of the cavity and stays that way. While the cooling take place, the screw will rotate, bringing in more pellets for the next part.
When the part is ready to be removed from the mold, the clamp will open, and the part will be removed from one half of the mold. Then the part will be Ejected from the other half of the mold, and the injection molding machine will start a new cycle.
Ningbo Haihang Plastic Machinery Manufacturing Co.,Ltd is a full-service, family owned custom injection molding machine currently serving clients in a broad range of industries, including aerospace, automotive, consumer, industrial and medical.
