Much has been written regarding design guidelines for injection molding. Yet, the design guidelines can be summed up in just a few design rules.
- Use uniform wall thicknesses throughout the part. This will minimize sinking, warping, residual stresses, and improve mold fill and cycle times.
- Use generous radius at all corners. The inside corner radius should be a minimum of one material thickness.
- Use the least thickness compliant with the process, material, or product design requirements. Using the least wall thickness for the process ensures rapid cooling, short cycle times, and minimum shot weight. All these result in the least possible part cost.
- Design parts to facilitate easy withdrawal from the mold by providing draft (taper) in the direction of mold opening or closing.
- Use ribs or gussets to improve part stiffness in bending. This avoids the use of thick section to achieve the same, thereby saving on part weight, material costs, and cycle time costs.