Design for injection molding

Explore the important considerations and design practices while designing for injection molding for design engineers

Injection molding -The go-to manufacturing process for producing large volumes of plastic parts with complex geometries

The process involves injecting molten plastic material into a mold, where it cools and solidifies to form the desired shape.

Considerations : Design for Injection molding

Molten plastic will take Path of least resistance hence the design should be such that the flow is not resisted into areas of the mold cavity

Part cavity should be such that it makes it easier to flow and not obstruct the flow.

Like in Casting Large volume and low surface area are not desirable. Will cause differential cooling and hence result in defects.

Location of parting line defines the flow of molten plastic . Its best to have the parting line across the larger area of part

Deeper a cavity goes the more difficult it is TO MAINTAIN QUALITY as the cooling period for the plastic extends.

Undercuts should be avoided

Cores (which are used in molds to create cavity in parts) should be avoided as much as possible. But in places where they cannot be , the core removal should be made easier and effect on quality should be reduced.

Gating system in Injection molding :

The gating system in injection molding is a network of channels that guides molten plastic from the injection unit into the mold cavity. It plays a crucial role in ensuring smooth, efficient flow and minimizing defects in the final part.

Generally a point and direction which is centrally located would be best choice to make sure the fluid reaches the extent of the cavities

placed at the Heaviest cross section to allow for part packing and minimize voids and Sinks

Draft angles :

Draft angles are incorporated into the design of the mold to facilitate the easy release of the finished part. These angles prevent damage to both the part and the mold during the ejection process, enhancing production efficiency.