Plastic shrinks as it cools from a molten liquid to a solid form. To achieve the intended final dimensions, the mold cavity must be scaled up during the design phase.
What are you using? (e.g., ABS, Nylon, Polycarbonate) Is this for high-volume production or prototyping ? Do you need advice on undercuts and lifters ?
Corrosion-resistant against corrosive gasses; mirror finish. 3. The Feed System: Sprues, Runners, and Gates
| Resin | Shrinkage (mm/mm) | Notes | |-------|-------------------|-------| | PP (unfilled) | 0.012–0.022 | Highly crystalline | | ABS | 0.004–0.007 | Good stability | | PC | 0.005–0.007 | Low shrink | | Nylon 6/6 | 0.008–0.015 | Very moisture-sensitive | | POM (Acetal) | 0.018–0.025 | High shrink | | PS | 0.003–0.006 | Amorphous |
: Maintain uniform wall thickness across the entire part. injection mold design guide
An undercut is any feature (such as a hole, recess, or snap-fit latch) that prevents the part from being directly ejected along the linear axis of the mold opening. Undercuts require moving mechanical components inside the mold, which increases tooling costs significantly.
: Keep maximum rib height below 3x the nominal wall thickness to avoid filling and venting issues.
Ideal for prototyping or low-volume production due to lower cost and faster machining.
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An injection mold design guide is the blueprint for manufacturing success. It bridges the gap between a 3D model and a physical product, ensuring the part is functional, aesthetic, and cost-effective.
Simulation plays an increasingly important role in injection mold design, allowing designers to optimize the mold design and predict potential problems. Simulation can help:
Keeps cooling rates even to prevent internal stress.
Injection mold design is a discipline of compromise. You must balance: If this air cannot escape
: Increase draft by 1.0° to 1.5° for every 0.025mm (0.001 in) of texture depth.
As molten plastic shoots into the closed mold cavity, it violently displaces the air inside. If this air cannot escape, it compresses rapidly, heats up, and burns the plastic (known as "diesel effect" or burn marks).
Sharp corners create massive stress concentrations in both the molded plastic part and the steel mold itself. Under mechanical load, parts almost always fail at a sharp internal corner.