This will describe the structure of 2-plate, 3-plate, and runnerless molds.
The basic structure of injection mold is determined by the geometry of the product,

its production volume, molding material, and consideration of other technical and production constraints such as positioning of gate.

2-Plate Mold Configuration

The mold is divided by parting-line (PL) into two parts, the movable and fixed side.

Features:

The structure is simpler compared to 3-plate and runnerless mold.

Tooling cost is normally lower.

Side gate, submarine gate, and direct gate system are typical. More about gate system.

   Drawbacks:
Side gate and direct gate are not suited to save labor cost through automation.

  3-Plate Mold Configuration
The mold is divided by 2 PL into three separate parts. The 1st PL is on the runner separating the runner stripper plate and the fixed side plate. The pin-gate is automatically cut off from the product on 1st PL. The 2nd PL is on the product separating the movable and fixed sides.

   Features:
Suitable for full automation.

Drawbacks:

Mold structure is more complex than 2-plate structure.

Tooling cost is higher.

Runnerless Mold Configuration

2-plate and 3-plate molds produce product plus runner. Runnerless molds can be achieved by introducing hot runners.

Features:

Runners will not be discarded at all so cost of material is less.

Sprue and runner is always in the heater maintaining its fluid state for good filling of molten plastics to cavities.

There are several advantages for high volume production.

Suitable for full automation.

Drawbacks:

Complex structure.

Much higher price.

It takes time to replace the material.                         

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First-rate Mold Solution Co., Ltd. in China, provide industry design,mold design,mold manufacturing,molding analysis,project management service.

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