3D Printed Mold Tooling Advances in Performance With Proprietary Resin

Injection molders’ growing need for quickly produced tooling is not new; but the increasing viability of molds 3D printed in polymer is. Oftentimes, the challenge associated with traditional mold tooling is the lengthy lead time, and 3D printed molds made from polymers can offer a faster solution. However, the usefulness of currently available tooling made this way is limited. The life of the tool as measured in the quantity of molded parts it can deliver is low, and the surface finish of the printed mold may rule out producing smoother parts.

However, material improvements promise to respond to both limitations, extending the life and application range of 3D printed polymer tooling. Developments by additive manufacturing technology firm Fortify provide an example. The company makes molds by applying a proprietary resin suitable to the short-term demands of injection mold tooling. In a recent webinar, Fortify application engineer Craig Crossley, along with Ryan Lariviere, program manager for Empire Group (Fortify’s contract manufacturing partner), described some of the application possibilities they are seeing using 3D printed polymer molds.

Not All Materials Are Created Equal

Crossley says Fortify’s resin, besides being strong and rigid, offers a high heat deflection temperature (HDT). The higher the HDT, the faster the molding process will be. This feature offers increased alternatives for tooling and production at a faster pace. 

Previously mentioned, the application of 3D printed polymer mold tooling is considered limited regarding quantity of parts able to be produced (as well as shelf life in some cases). Yet lead time and cost pressures challenge plastic part producers to find alternatives to conventional mold tooling. One alternative is 3D printing as a short-term bridge production method, while another solution lies in the ever-advancing material variations available for on-demand molds. 

According to Crossley, Fortify is molding parts made with a range of plastics — from commodity to high performance options. These can include carbon fiber filled PEEK, liquid crystalline polymer and glass filled nylons among other materials.

The three-part selection process for 3D printing these mold tools recognizes part size, quantity and complexity as the main criteria. 

Crossley says the ideal molded part size for this tooling fits into a three-inch box, as the smaller size offers optimal print time and is thus an economical way to keep costs down. While possible to print to the full size of the 3D printer’s build volume, cost and time advantages decline with greater size.

As far as quantity goes, “Up to 200 [molded] parts is the most effective way to leverage 3D printing,” according to Crossley. This equates to no more than one single day of molding time. Cycle times per shot are currently between one and five minutes, but this is coming down thanks to experimentation with cooling methods, Crossley says.

The final component is part complexity. This factor is harder to generalize, he says. 3D printed tooling brings significant ease to obtaining complex forms to meet designers’ exact needs, but more complex features can sometimes reduce tool life. 

Case Study Success

Lariviere describes the application possibilities 3D printed polymer molds afford through case study successes. One such project Lariviere details was on behalf of Keurig. 

The goal of the project was to create injection molded parts for various prototypes of Keurig coffee makers. The prototypes had to meet specified requirements — withstanding boiling water and functioning on a four-week lead time. According to Lariviere, there were five variant geometric parts in total, with about 30 units of each part needed, with a three-week timeline to produce operational tooling. 

“Any issues we had, if we had to print new inserts, we were able to do that overnight,” he says. 

The real-time feedback from rapidly printing tools thus assisted in experimentation. If one experimental part failed, the tool for the next part design was readily available to advance further testing. 

The Finishing Touch 

Postprocessing is another complication of 3D printed mold tooling that material changes have the power to address. 

Traditional 3D printed mold tools often retain surface roughness as post-processing is difficult to perform on the materials currently available, Crossley says. 

But the proprietary resin Fortify uses can be polished with up to an A2 finish for a smoother end-result. 

This is every bit as important as the life and molded material range of the tooling, he says. For 3D printed tooling to be valuable, it needs to not only deliver parts quickly, but also deliver parts comparable in quality to conventional tools.