Selection of mold type depends on component design, budget and volumes of the parts to be produced. During new product development, manufacturer always ask. What type of mold is required? 1) single cavity, multi cavity or family mold, 2) Hot runner or cold runner mold 3) Two-plate or three-plate mold. Accordingly manufacturer provide tool estimate. If you demand, manufacturer can also suggest ways to reduce mold price.
In this article we will discuss what are two plate and three plate molds their advantages and disadvantages.
Two Plate Mold
Two-plate mold are most commonly used type of molds. It consist of one parting plane and the mold splits at parting plane. In a multi cavity two plate mold, runner and gate must be in parting plane. So that they can be ejected when mold splits.
Two-Plate molds are used for parts that are gated on or around edge we the runner on cavity mold plate.
Advantages of Two-Plate Mold
- Simple and low cost design.
- Less lead time
- Lower cycle time compared to three plate mold.
Disadvantages of Two-Plate Mold
- For multi cavity two plate mold, parting line must be aligned with gate.
- In multi cavity tool, Molten plastic flow balancing is a challenging task.
Three-plate mold consist of two parting planes and mold splits in three sections. Therefore runner and component can be located on different parting planes. It is used when some part of runner system is in different plane to injection location.
In three-plate mold runner is ejected separately to molded part.
Advantages of three-plate mold
- Flexibility in gating location.
- Low cost alternative to hot runner mold.
Gate removal operation is eliminated.
Disadvantages of three-plate mold
- Higher injection time due to ejection of runner system.
- More complex tool design.
- High injection pressure is required.
- High material wastage.
To sum up, two plate molds are most commonly used molds. It consist of one parting plane and mold splits in two halves. Whereas three plate mold consist of two parting planes and mold splits in three sections. Two plate mold is a low cost solution. Whereas three plate mold can be an alternative to hot runner mold.
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