Design for Plastic Manufacturing
Qualitative Best Practices
- Choose a material that is suitable for the intended function, performance, and appearance of the part. Consider the properties of the material such as strength, stiffness, toughness, thermal stability, chemical resistance, color, and recyclability.
- Minimize the number of parts and features in the design. Simplify the part geometry and avoid unnecessary details such as sharp corners, undercuts, thin walls, and deep cavities. This will reduce the mold complexity and improve the quality and consistency of the part.
- Design the part with uniform wall thickness and avoid abrupt changes in cross-sections. This will prevent defects such as warping, sink marks, and stress concentration in the part. Use ribs, gussets, and bosses to reinforce the part and provide attachment points.
– Design the part with adequate draft angles and smooth surfaces. This will facilitate the ejection of the part from the mold and reduce the friction and wear on the mold. Use textures or patterns to hide minor defects or scratches on the part surface.
– Design the part with proper gate location and size. The gate is the point where the molten plastic enters the mold cavity. The gate location and size affect the flow pattern, filling time, pressure, and temperature of the plastic in the mold. The gate should be placed in a less visible area of the part and should be large enough to allow sufficient flow of plastic without causing excessive shear stress or jetting.
– Design the part with proper venting and cooling channels. Venting allows air and gases to escape from the mold cavity during injection. Cooling channels circulate water or other fluids around the mold to control the temperature of the plastic in the mold. Venting and cooling affect the cycle time, shrinkage, warpage, and dimensional accuracy of the part.
Plastic part manufacturers are a great resource to find more guidelines and specific expert support for plastic part manufacturing.
For example, see: 8 Factors in Plastic Part Design for Manufacturability (nicoletplastics.com)
