The following design principles should be considered when designing an injection mold:
Common and easy to machine, but they leave a visible scrap mark on the parting line. injection mold design guide
| Material | Shrinkage (in/in) | Key Design Consideration | | :--- | :--- | :--- | | ABS | 0.004 – 0.007 | Good flow, easy draft. | | Polypropylene (PP) | 0.010 – 0.025 | High shrinkage. Requires large drafts. | | Polycarbonate (PC) | 0.005 – 0.007 | High viscosity. Requires larger gates. | | Nylon (PA6/66) | 0.007 – 0.020 | Hygroscopic (absorbs water = swells). | | POM (Delrin) | 0.018 – 0.025 | Very high shrinkage. | The following design principles should be considered when
How many parts do you need? This dictates the steel and the cost. Requires large drafts
Position cooling channels symmetrically around the cavity and core.
MOLD OPENING DIRECTION ( ^ ) | | _______| |_______ | __________________ | <--| | Sliders / Side | |--> (Slides move outward to | | Actions Release | | release external undercuts) | |___Undercuts_____| | |______________________|
Highly resistant to corrosion. Required for PVC processing (which releases corrosive gasses) and optical parts needing a high-gloss finish.