Injection Mold Design Guide Direct

: The outer diameter should be roughly double the screw diameter.

End your design process by conducting a comprehensive review alongside your mold maker. Catching geometry flaws on a computer screen is virtually free; fixing them once tool steel has been cut costs thousands of dollars and weeks of production time.

The you plan to use (e.g., ABS, PP, Nylon, Polycarbonate) The anticipated production volume for this tool

The final page was blank except for a single line: “If you forget everything else, remember this: air is not your friend. It burns, it traps, and it lies.” injection mold design guide

: Use these features to add strength or provide attachment points without thickening the main walls.

| Mold component | Common steel | Hardness | Application | |----------------|--------------|----------|--------------| | Cavity / Core | P20 | ~30 HRC | Low-to-mid volume (<500k shots) | | Cavity / Core | H13 / S7 | 48–52 HRC | High volume, abrasive resins (glass-filled) | | Slides / Lifters | D2 / A2 | 58–60 HRC | Wear surfaces | | Mold base | 4140 / 1050 | ~28 HRC | Plates, support pillars |

Aris scribbled a note: Confirm shrinkage factor with resin supplier. Design nominal geometry, then scale up by shrink rate. Never guess. : The outer diameter should be roughly double

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When a part contains through-holes, the steel of the core must meet the steel of the cavity to block plastic flow. This contact area is a shut-off. Designing shut-offs with a slight angle (typically 3 to 5 degrees) prevents the steel faces from rubbing directly against each other, reducing tool wear. Dealing with Undercuts

Good for medium-volume production.

For deep-drawn, thin-walled parts (like cups or containers), ejector pins will puncture the part. A stripper plate pushes against the entire perimeter of the part simultaneously, providing uniform ejection force without leaving pin marks. 8. Mold Material Selection

He turned the page. A crude drawing showed a fortress wall—thick at the base, thin at the battlements. The caption read: “Uneven walls create ghosts: voids, sinks, and residual stress.”