Injection Mold Essay

The world has become very dependent upon plastic products. From household items to industry and aerospace, plastic in its many formulations has transformed modern manufacturing and created conveniences and economies unimagined in the early decades of the 20th century.

Injection Molds

The injection molding industry took hold in 1946 when James Hendry built a screw injection molding machine. But, his technology was based on an earlier invention by John Wesley Hyatt who, in 1868 injected hot celluloid into a mold to make billiard balls. Hyatt's method used a plunger to force the material inside a mold. Hendry's improvement was revolutionary because it eliminated the plunger and replaced it with an auger-type action that better distributed material and facilitated the use of plastic inside molds.

Today's injection molds use much the same process and produce a wide variety of products from car panels to

Molds are made of hardened steel or, more recently, aluminum which is less expensive.

The Injection Process

Described very simply, molten plastic is injected into the mold under high heat and pressure. The goal is to have the molten plastic material evenly flow to all parts of the mold, creating an exact, consistent, solid plastic replica of the mold cavity. After a brief cooling cycle, the mold or tooling mechanically ejects the plastic part which then moves on through the manufacturing process. In the injection molding industry, this is a completely automated process that's very fast and extremely efficient.

Rotational Molding

Rotational molding is yet another method of producing multiple products, most often made with a variety of plastic powders. This process is usually used in making hollow products such as traffic cones, canoes, kayaks, bicycle helmets and giant tanks used for water or chemical