You need a stiff part. Your instinct is to thicken the wall. Stop. That creates sink marks.
Instead, use ribs. A rib is a thin, vertical wall of plastic that adds stiffness like an I-beam in steel construction.
The Essentials of Injection Molding Part Design: A Beginner’s Guide injection molding part design for dummiespdf exclusive
Injection molding is a widely used manufacturing process for producing high-quality plastic parts in large volumes. While it may seem complex, the process follows a few fundamental principles that, when understood, can significantly improve part quality and reduce production costs. This guide covers the essential design rules every beginner should know. 1. The Core Principle: Uniform Wall Thickness
One of the most critical rules in injection molding is maintaining a uniform wall thickness throughout your part. Inconsistent walls cause the plastic to cool at different rates, leading to several defects: Injection Molding Part Design for Dummies (For Dummies) You need a stiff part
While a specific book with that exact title does not exist (it is likely a keyword string used on file-sharing sites), the "For Dummies" brand does publish a highly regarded book on this topic called "Injection Molding Design for Dummies" (typically authored by experts from Xometry or similar manufacturing networks).
Here are the key features and takeaways you would find inside such a guide, distilled into a quick-reference summary: That creates sink marks
Try pulling a plastic cup out of a bucket of wet sand. If the cup has straight vertical walls, the sand (or in our case, the steel mold) will grip it like a vice. You need an angle—a draft.
Draft is a slight taper on vertical faces that allows the part to release from the mold without scratching or sticking.
Example: If your wall is 2mm thick, never design an inside corner smaller than 1mm radius.
Do not design zero-draft parts. Even if your mold builder says "we can try," you will pay for it in rejected parts and mold damage.