Injection Mold Design Guide [better] 【ORIGINAL — 2026】

Rib thickness should be 40% - 60% of the nominal wall thickness to avoid sink marks on the opposite surface.

Runners distribute plastic from the sprue to the gates. They generally fall into two categories:

Every plastic behaves differently. You must compensate for .

The part shrinks onto the core (B-side) as it cools. It must be pushed off forcefully without marking or distorting it.

Ensures the part slides out smoothly without drag marks. 3. Ribs and Bosses These add strength without adding excessive weight or cost. injection mold design guide

When designing an injection mold, several key considerations must be taken into account to ensure the production of high-quality parts. These include:

The runner system connects the machine nozzle to the cavity.

Connect bosses to walls with ribs or gussets for stability and better flow. 4. Gating and Venting

: Maximum rib height should not exceed 3 times the nominal wall thickness to avoid filling issues and thin steel sections in the mold. Rib thickness should be 40% - 60% of

: Rib thickness should be 40–60% of the nominal wall thickness to prevent sink marks on the opposite surface. The Anatomy of a Mold

Ignoring any of these four pillars results in catastrophic failure.

Need a mold quoted? Ensure your supplier has a DFM (Design for Manufacturing) report process. If they cut steel without sending you a DFM, find a new supplier.

Adhering to these design rules ensures the "manufacturability" of your plastic part (Design for Manufacturability, or DFM). A. Wall Thickness You must compensate for

(usually 40–60% of the nominal wall thickness) instead of thick solid sections. 2. Core Components of Mold Design The Injection Moulding Process: A Complete Guide - Geomiq

Predicts how the part will change shape after cooling. 5. Design Checklist for Success Does the part have proper draft angles? Is the wall thickness uniform? Are all sharp corners filleted? Is the gate type suitable for the material and finish? Are ribs and bosses designed to prevent sink marks? Has a cooling analysis been conducted? Does the ejector system prevent damaging the part?

Avoid sharp corners, which create stress concentrations. Use an internal radius of at least 50% of the wall thickness Ribs & Bosses: To add strength without adding mass, use