In general engineering designs, when a shell model approach is used, ribs is often added to support the structure. But this often come with a doubt, how do we decide the thickness of the ribs? The purpose of having a shell model (hollow structure) is to remove the unnecessary material to prevent the over engineering of a part, but when its shallow, supporting material is required. The introduction of ribs provides the support needed on the shell model, but if too much materials are included in this supporting feature, a sink mark will appear on the outer surface of the part, especially on plastic parts in injection molding. A sink mark is a depression on the local surface when ribs or internal bosses of the part is thick. This is not always necessarily a negative thing, but its undesirable when the sink mark appears on the surface that’s displaying surface.
This is where the Thickness Analysis tool in SOLIDWORKS can help, it provides us a heat map showing us the magnitude of thickness on each surfaces, and allows us to check if the thickness at each part is appropriate.
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