FAQ On Plastic Injection Molding

What is injection molding?
In injection molding, plastic granules are heated and "injected" under pressure into metal molds, where the molten plastic hardens into a designated shape. The mold then opens and the newly formed part is removed and inspected, ready for shipment or secondary manufacturing operations. Injection molding is an extremely versatile and popular form of molding. Other processes include extrusion, thermoforming, and blow molding.
What is insert molding?
Injection molding becomes insert molding when a specifically designed insert (typically of metal) is nested in the mold before the molten plastic is injected. The plastic hardens around the insert and the resulting part is a combination of plastic and insert. A simple example would be certain scissors in which metal blades are inserted into the mold, and plastic handles are molded around the blades.
What is an injection molding machine?
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 following diagram, Figure 1, illustrates a simplified injection molding machine.