When designing parts for thermoplastic injection molding, you want to follow guidelines for wall thickness, radii and chamfers, draft angles, corrugations, ribs and gussets, and bosses and holes—look no further than Envalior’s new online Design Guide to help you follow the correct guidelines per application requirements.  

Thermoplastic materials have much to offer for a variety of applications. They are available in a range of base polymers and can be tuned to meet specific requirements by including additives. In order to make optimal use of the inherent characteristics of these materials—such as high strength to weight ratio, non-conductive properties, flexibility and chemical resistance—it is necessary to be consistent when designing an application, so the part is produced smoothly and meets expectations. The Design Guide is a tool to help engineers, designers and mold makers create parts that meet structural performance, weight, cost and aesthetics requirements.

Wall thickness: Specifying a parts nominal wall thickness is the first step in determining its manufacturability, performance and cost.

Radii and chamfers: Applying radii or chamfers to sharp corners is of key importance for parts manufacturability, dimensional accuracy and load-carrying capacity.

Draft angle: Part surfaces parallel to the draw direction of the mold should be tapered to facilitate ejection of the part after molding.

Corrugations, ribs or gussets: By applying corrugations, ribs or gussets to a parts functional geometry, its structural performance can be improved.

Bosses: A boss is a cylindrical protrusion on a part and can have various functions, such as a positioning aid, a fixation point or a bearing surface.

Holes: A hole in a part can have many functions, including acting as a fixation point, offering passage to other parts and reducing a parts weight.

Coring: In the design of injection molded plastic parts, thick sections should be avoided. Coring, locally eliminating material in these sections, is a way to pursue a uniform wall thickness.

Undercuts: If a part has an undercut, it means that it can’t be ejected from the mold without taking specific measures regarding tool construction or additional operations during the molding cycle.