Plastic extrusion has had a huge impact on companies and consumers for some time now. It supplies companies with products such as window frames and wire insulation. But I caught my eye on a word the other day, Injection Molding. It's pretty interesting and had bigg impact on the industry of plastic and our lives. First being founded in the 1930's, injection molding was first created off of the design of a metal cast die. This is where people should take some time out and read into polymer injection molding. It is a simple and great technique due to many remnants or scraps that can be melted and recycled; sort of like a never ending supply circle. Injection molding differs from molten metal by the molten metal can be poured while the plastic must be injected.

The Injection Molding process uses large injection molding machines, which advance the resins to six processes to develop a product. Products range from small Halloween spiders to larger plastic products.

The machine consists of an injection unit and a clamping unit. It begins with a mold which is clamped under pressure to accommodate the injection and cooling process. After being clamped small beaded resins are fed into a machine with added colorants.

After it is fed into the machine, the resins fall into a barrel and heated down to their melting point. Then while in its molten state, shot into the mold with a screw or ramming device. After successfully in the mold, it's time for a process called the 'Dwelling Phase'.

The dwelling phase is an interesting part of the process. It is when the plastic is inside the mold, and hydraulic pressure or mechanical pressure is applied. So much pressure is needed to fill every hole and crack. The plastic that has been forced down then is allowed to cool in the mold.

The mold is opened by separating the two pieces in half. Injection Pins force the plastic out in the final step. The product may have extraneous bits called runners. These runners are simply trimmed and recycled. The whole process is cyclical with some cycle times ranging from between 10 and 100 seconds.

That all depends on the cooling time and whatever the company's policy is. This is interesting; every type of resin has a shrinkage value that must be factored into the melting equation. If the equation is wrong the storm shutters will be the wrong size or shape. Warpage is also a problem that needs to be avoided.

If temperatures are too high uneven spaces may set on the product as well. The total filling of the mold may not be to its capacity as well. The molding is done with no foreign imports, all American.