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 single cavity multi cavity and family molds.
Single Cavity Mold
As the name suggest, Single cavity tool consist of one cavity. Therefore one single part is produced per injection cycle. If product volumes are not very high, single cavity tool is good choice.
- Single cavity tool cost will be less compared to multi cavity tool. Therefore initial investment will be less.
- Single Cavity tool is easy to produce, require less machining. Therefore lead time for single cavity tool will be less.
- Instead of producing one two cavity tool some companies prefer prefer two single cavity tool. Because in case of breakdown in one tool, second tool still can be used.
- Single Cavity tool produces one single part per injection shot. Therefore production rate will be less.
- Single component is produced in single cavity tool. That increases component unit price.
Multi Cavity Mold
As the name suggest, multi cavity tool consist of more than one cavity. Therefore more than one part is produced per injection cycle.
Multi cavity injection mould produces more than one part per cycle. Initial investment cost is higher but unit part cost is low for multi cavity injection tool.
Multi cavity mold are used to increase production rate.
- More than one part is produced per cycle. Therefore cycle time and cost for one part will be reduced.
- Higher volumes of injection molding part can be produced in small time. That results in high production rate
- Multi cavity injection tools are more expensive compared to single cavity tool.
- Higher tonnage machine is required to run a multi-cavity tool.
- Longer lead time for mold manufacturing.
Family molds are used to produce two or more different components in same material per injection cycle. With Family mold overall tool cost is reduced as two different parts are manufactured with single mold.
- This is a cost effective solution. Molding tool cost for two. Family molds are more expensive compared to single cavity tool. But here in the cost of one mold, we get molds for two different components.
- Similar to multi cavity molds. In family mold two or more components are produced in one injection cycle.
- Molten plastic flow balancing in cavities of different components becomes a challenging task. That can results in various quality issues.
- Family mold produces different parts in the same material. Therefore requirement of different materials for different components can not be fulfilled.
To sum up, A single cavity mold produces single component per injection cycle and multi cavity mold produces more than one component per injection cycle. Whereas in family mold multiple components are produced in one injection cycle. To understand type of molds, we suggest you to read this article on hot runner and cold runner molds.
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