LAUSR

Vent holes in thermoforming tooling are traditionally round and run perpendicular to the tool surface, as this is easy to produce via drilling and minimizes surface imperfections. This geometry should be reevaluated when producing tooling via fused deposition modeling (FDM). FDM offers thermoformers the possibility of lower tool cost and reduced lead-time compared to traditional aluminum molds. With FDM it is easier to create vent holes, even very small ones, in difficult-to-access locations. This is especially true if the holes have a rectangular cross section and lie parallel to the build plane. This alternative geometry requires modified rules to estimate the required number of holes and the size of dimple on the final part created by the vent hole during forming. In addition, FDM will produce holes with a very rough surface finish, potentially impeding flow. Computational fluid dynamics was used to show that this concern is unwarranted in practice. Finally, the Markforged Mark 2 printer was used to produce test holes, and their suitability for thermoforming is discussed.