Injection Mold Types


There are many injection mold types. This site will attempt to explain the basics of some injection-mold-types here. The information may seen basic to those who are in the molding business, but I feel the layman deserves an overview before we proceed with details

Injection Mold. What is it?

An injection mold is a group of parts; bolted together to form a hollow space in the obverse of the part desired to be molded. Often this consists of one piece hollowed out in the shape of the exterior of the part, and it may become the stationary mold half. A second piece consists of the interior of the part, has ejector pins to remove it from the mold and is called the ejector half or moveable half.

Melted plastic is injected into the mold thru a sprue and runner system. When the plastic gets to the cavity area it goes thru a restricted area called the gate. The gate is smaller than the runner and makes it easier to break the part off of the runner after molding.

After the plastic is injected into the mold cavity area, an amount of time will elapse to cool the plastic to a solid, and then it can be ejected from the mold without deforming.

The part falls out of the mold, and the cycle is repeated to get more parts.

Injection Molding Machine. What is it?

An injection molding machine consists of:

1)A frame in which to mount the mold. This frame has a moveable section with the ability to open and shut the mold, and to run an ejector system within the mold. When closed it exerts tons of pressure on the mold to keep it closed when the plastic injects.

2)A plasticising unit for melting the plastic. This is often referred to as a screw and barrel. Electric heater bands placed around the barrel normally heat it. The screw turns within the barrel adding mechanical heat to the process, but this turning action alone is not enough to melt the plastic.

3)An injection unit for forcing the plastic melt into the mold with pressure.

4)Controls for making all of the above work together in the proper sequence.

Mold Particulars

Injection Mold Types for design.

Conventional Cold Runner Molds (two plate) two plate molds

Three plate Runner Molds

Hot Runner Molds

Insulated Runner Molds

Molds with Slides

Molds with Lifters

Molds with Sub-gates

Molds with Edge gates

Molds with Diaphragm gates

Molds with Sprue gates
Of course there are many more injection mold types and sub-types.We will add to this page as time allows, so check back occasionally Leave Injection Mold Types and return to Injection Mold Tips home page

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