Skip to main content

Wall thickness is crucial in the design and development of injection molded parts. Each molding resin has different optimal ranges for wall thickness. When designing for plastic products, following the guidelines presented here can help to avoid warpage, strength issues, and sink. See the included chart for recommended wall thicknesses for a number of industry-standard resins.

A part molds best when its nominal wall thickness is consistent and varies little from feature to feature. Molding a part that has significant differences in wall thickness will result in difficulties filling the mold and possibly warpage, sink, cosmetic issues, or other unwanted design problems.

Designing thinner walls than what is recommended can cause flow issues and warpage, as the material must pass through an equally thin section of metal, slowing the material flow and creating resistance. Thin walls can also have warpage, like a crinkled shirt. This warp is due to the material’s lack of stability as the part cools.

Thick walls can have a tough time cooling because the material is still molten at the center of the wall. Sink is caused when the exterior of the part is cooler than the interior. Thick walls in a part’s design can also create issues such as internal voids, excessive shrink, warpage, and dimensional inaccuracies. See the included picture for a thickness analysis completed on an over-molded handle.

Molded Dimensions Group provides thickness analysis for all new products being developed with our engineering team. In a process called Design for Manufacturing (DFM), we help customers with the design and development of the injection mold tool used to make the plastic part.

In this process, we talk through the design with the customer, advising of areas that may need to be improved in order to make the part easily manufacturable. This process also helps identify key areas for cost reduction or increases in quality.

DFM is a fantastic way to catch issues that could potentially be problematic at production. The goal is to develop a part that will work perfectly in its intended application and last for many years. The engineering team at Molded Dimensions Group has over 25 years of experience in the injection molding industry. We are available to assist you with the design and development of your product—reach out to our team today to learn more.

Access more articles in our Plastic Knowledge Center.