There’s a persistent myth in injection molding that goes something like this: “If the part is warping, just add ribs and it will flatten out.” It sounds logical. Ribs add stiffness, stiffness fights deformation — therefore: flatter part, right? Well… sometimes. But just as the Earth isn’t flat, your part won’t magically become flat just because you threw a rib pattern at it. In many cases, ribs can actually increase warpage if they’re not designed with the material and flow b