A plastic injection machine consists of a mold and a clamping system on the far side of the machine. The clamping system keeps the 2 halves of the mold tightly shut while the heated plastic is injected. It also pushes the molded part out of the mold after it opens, and then dispenses the molded part onto a conveyor belt or in a holding container.

Mold: The mold is made out of aluminum or tool steel and is CNC machined to a required standard. It usually includes a runner system that facilitates the flow of material into the mold, and internal water cooling channels to aid the cooling process.
Design: The design of the mold must be accurate to produce a good-looking molded part. It must also be durable enough to withstand the many cycles of injection molding and ejection without being damaged.
Wall Thickness: Thinner walls reduce part volume, which increases the efficiency of the cycle. This is particularly important for parts that will be exposed to high heat or pressure during use.
Choosing the Right Mold Materials: Choose a thermoplastic that offers the properties you want for your part, including heat deflection and abrasion resistance. You can also opt for a thermosetting material that offers flexibility and strength.
Selecting the Correct Molding Conditions: The molding conditions - such as cylinder temperature, injection speed, and mold temperature - used in an injection machine affect the appearance, size and mechanical properties of the molded parts. The number of possible combinations is very large, and experience is needed to select the most suitable ones.