Design Guidelines for Additive Manufactured Snap-Fit Joints

Abstract

Snap-fit joints are one of the cheapest and fastest connectors available. However, due to geometrical complexity of the joints and the limitations of injection molding, they are used almost exclusively in large-scale manufactured products. Additive manufacturing offers the possibility to create end-user products in small and medium numbers with almost unlimited design complexity. This clears the way for new solutions using snap-fit joints to be explored. In this contribution, the existing design guidelines for snap-fit joints are challenged with the design potentials of additive manufacturing. The general working principles of snap-fit joints prove to be simple, clear, and safe independent of the manufacturing process. While the principles remain unchanged, the advantages of additive manufacturing are utilized to improve the integration in the product and the user handling. By applying the design restrictions of the additive manufacturing processes Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) the existing guidelines are extended for new manufacturing processes. To demonstrate the new concepts and the capabilities of additive manufactured snap-fit joints a showcase is conceptualized, designed in detail and produced using Fused Deposition Modeling and Selective Laser Sintering. A lid of a container, similar to a jar, is designed as an integrated single component. Aspects of haptics and usability are integrated, resulting in a lid that can easily be assembled and disassembled using one hand only. The design features springs and snap-fit joints adapted to the advantages and limitations of additive manufacturing.