Polymer Additive Tooling for Injection Molding

Injection molding (IM) is the second most used process in polymer processing, consuming approximately 32 wt.% of all plastics. IM generally uses steel molds capable of producing millions of parts. The complexity of the mold cavity will affect the tooling time and investment required; it could take months and a capital investment of $50,000 or more, and any modification in the geometry of the part will require a new mold. Therefore, injection molding manufacturers have used a replaceable aluminum insert to create prototypes for functional testing and to produce low volumes of parts. Nevertheless, these inserts are also fabricated with conventional tooling techniques (machining or electro-discharge machining).

Recently, additively manufactured polymer inserts are replacing their metal counterparts. These inserts are a great option for low volume injection molding. The lead time and cost of 3D printed polymer inserts are significantly reduced compared to conventional metal tooling. The use of rapid prototyping (such as 3D printing) to directly produce a mold is known as direct tooling. Processes used for this type of polymer tooling commonly include selective laser sintering (SLS), fused filament fabrication (FFF), stereolithography (SLA) and material jetting (MJ).

This work focuses on determining the maximum number of cycles before failure for two different 3D printed polymer insert materials obtained via MJ and SLA. Additionally, mechanical and thermal properties of the parts manufactured with these inserts are compared to the same geometry produced with a steel mold.

Contact: camila.montoya@wisc.edu