Injection Mold Design Guide __full__

If you skip draft, you will never eject the part. As plastic cools, it shrinks onto the core side of the mold. Draft angles allow the part to break free.

The mold design process typically involves the following steps: injection mold design guide

The solution was a vent: a shallow groove (0.02mm deep) along the parting line, just deep enough for air to escape but too shallow for plastic to flash. It’s invisible to the naked eye but as critical as the heart to a body. If you skip draft, you will never eject the part

Before building the mold, a good mold maker will return a DFM report showing how they intend to split the core/cavity, where the gates are, and what concerns they have. Never skip the DFM. It is cheaper to change a 3D model than to weld up a block of steel. The mold design process typically involves the following

| 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 |