The part shrinks onto the core (B-side) as it cools. It must be pushed off forcefully without marking or distorting it.
| Ejector type | Use case | |--------------|----------| | Round ejector pins (2–10 mm dia) | General – standard | | Sleeve ejectors | Around core pins (hubs, bosses) | | Stripper plate | Large flat parts, thin-wall | | Air poppets | Deep ribs, fragile features |
Layout rules:
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.
The perfect injection mold design is never the first draft. It is the result of a DFM (Design for Manufacturing) review between the product designer and the mold maker. Share this Injection Mold Design Guide with your team and challenge every assumption. injection mold design guide
Remember: "It looks good on the computer" is not the same as "It ejects reliably on a cycle."
Implement these principles early, run a mold flow analysis, and respect the polymer. Your reward will be shorter lead times, lower tooling costs, and parts that fit right the first time. The part shrinks onto the core (B-side) as it cools
Need a downloadable checklist? Review sections 9 and 4 to create your internal design review form.
Cycle time = Money. Poor cooling = slow cycle + warped parts. | Ejector type | Use case | |--------------|----------|