Designing Living Hinges That Fold Flat and Last
A living hinge may be one of the simplest-looking features in plastic part design. It contains: Just a thin section of plastic connecting two rigid bodies. Yet despite its simplicity, the living hinge is one of the most frequently misdesigned features in injection molding. Many hinge failures occur long before the product reaches the customer. […]
Crush Ribs: Solving Tolerance Problems Without Tight Tolerances
One of the most common challenges in plastic product design is creating a reliable press fit. Consider a typical assembly: At first glance, the solution appears straightforward: Design the mating dimensions with a tight tolerance and create an interference fit. In practice, however, injection molding does not always favor this approach. Shrinkage variation, molding tolerances, […]
Design Parts That Are Easy to Change After the Mold Is Built
Every product team expects design changes during development. That is the purpose of prototyping. Engineers evaluate: And then make improvements. The problem is that not all design changes are equal. Some modifications can be completed by machining existing mold steel. Others require replacing inserts, rebuilding mold components, or manufacturing an entirely new tool. From a […]
Uniform Wall Thickness: The Single Most Important Rule in Injection Molded Part Design
When discussing injection molded part design, engineers often focus on: All of these factors influence the final product. However, if there is one design principle that has a greater impact on molding success than almost any other, it is this: Maintain uniform wall thickness. In practice, many molding defects—including sink marks, warpage, voids, dimensional variation, […]
Designing Molded Text: Small Features, Big Manufacturing Consequences
Almost every plastic product contains molded text. Examples include: From a CAD perspective, adding text is simple. From a molding perspective, text becomes another geometric feature that must: Many text-related defects are not caused by the text itself. They are caused by text being designed without considering how molds are manufactured and how plastic behaves […]