Injection Mold Design Guide (2025)

Designing an injection mold requires balancing part geometry, material behavior, and tool mechanical constraints to ensure high-quality parts and efficient production. 1. Part Geometry Fundamentals

V. Mold Material Selection

Height/Depth: Keep the height of raised text between 0.3 mm and 0.5 mm. Text exceeding 0.5 mm may require a draft angle to prevent the letters from sticking or breaking off during ejection. injection mold design guide

• Ejector Pins: The standard method. Use larger diameter pins on non-cosmetic surfaces to minimize the chance of piercing the part.
• Sleeve Ejectors: excellent for boss features (holes).
• Air Ejection: Used for thin-walled parts to avoid marking.
• Stripper Plates: Used for cylindrical parts or rings to provide full circumference ejection.

(ideally 1–3°) on all vertical faces to allow the part to eject smoothly without sticking. Rib & Boss Design should be roughly Ejector Pins: The standard method

• Cavity (A-Side): The female side; forms the outside shape of the part. Usually mounted to the stationary platen.
• Core (B-Side): The male side; forms the inside shape of the part. Usually mounted to the moving platen.
• Sprue: The channel through which molten plastic enters the mold from the nozzle.
• Runners: Channels that direct the plastic from the sprue to the cavity gates.
• Gates: The entry point where the plastic flows into the cavity. This is the critical control point for flow.
• Cooling Lines: Channels machined into the plates through which water or oil circulates to cool the part.
• Ejector System: Pins or sleeves that push the part out of the mold after cooling.
• Leader Pins & Bushings: Align the two halves of the mold precisely.

Boss Design: Connect bosses to walls with ribs or gussets for stability and better flow.  4. Gating and Venting  (ideally 1–3°) on all vertical faces to allow