Injection Mold Design Guide May 2026
Injection Mold Design Guide
Introduction
Injection molding is a high-volume manufacturing process for producing plastic parts by injecting molten polymer into a mold cavity. Good mold design optimizes part quality, reduces cycle time, and minimizes production costs. This guide covers essential design considerations, tooling elements, material selection, and common best practices.
To ensure a successful part, designers must adhere to three core pillars: uniformity, draft, and undercut management. injection mold design guide
Gates (The entrance):
- Sprue gate: For conical, deep-draw parts (high shear).
- Edge gate: Common for flat parts. Width = 2x thickness; depth = 0.7x thickness.
- Submarine (tunnel) gate: Gates are cut into the ejector plate. They self-degate when the part is ejected (automatic operation).
- Hot runner: No runners at all. Plastic is kept molten inside the manifold. Best for high-volume, material-sensitive parts.
Orientation: Place text perpendicular to the direction of the mold's pull (the line of draw). Placing text on tall features or angled surfaces can lead to "dragging" during part removal. Technical Trade-offs Sprue gate: For conical, deep-draw parts (high shear)
- Venting: Venting should be provided to allow air to escape from the mold during filling
- Venting location: Vents should be located in areas where they will not interfere with the part's functionality
- Venting size and type: The vent size and type should be selected based on the material and part requirements
