Heavy gauge/cut sheet thermoformers from companies across the US recently came to learn processing techniques, scientific principles, new material offerings, and more at the Pennsylvania College of Technology Plastic Innovation and Resource Center (PIRC). The program provides a 50/50 blend of classroom instruction with hands-on lab time in a lively 3-day setting. Program and Technical Service Manager Chris Gagliano developed the program to incorporate the expertise of consultant Jay Wadell with the science of plastic material properties from Dr. Kirk Cantor and the physics of thermal transfer from Dr. Joseph LeBlanc.
CMT Materials was asked to participate by providing a pre-release opportunity to work with a new mold material expected to demonstrate improvements in material distribution, mold weight and cost reduction, fast cycle rates – all from off-the-shelf materials that allow mold construction in under 24 hours.
Workshop participants confirmed the performance by making actual molds to allow comparison to a temperature controlled aluminum tool already in existence at the college.
The new material, HYVAC-LCM, utilizes a porous core covered with a layer of syntactic foam to eliminate the need for temperature control. Syntactic foam properties allow the cut sheet to hold its optimal forming temperature to ensure the plastic flows over the mold rather than chilling off and creating stress/orientation issues. The porous core provides easy access to a uniform vacuum by drilling through the syntactic foam at any location desired. (Many thanks to Chris Gagliano for sharing a great tip in demonstrating how a piece of cut piano wire held in a basic Dremel eliminated drill wear and quickly cut vent holes wherever needed!)
HYVAC-LCM was developed for the low- to medium-volume run market as a high performance alternative to wood at a fraction of the cost of an aluminum tool. The material may be made by first machining the porous core, coating the shaped core with a one-part syntactic foam putty, curing with heat, then machining to final geometry. Another option is to fill a pre-shaped negative cavity with both syntactic foam and the core for a single-step cure. Workshop participants were enthusiastic about both approaches depending on the equipment and expertise of their individual facilities. Those with 3D printers were especially interested in trying out their ability to quickly create a low cost negative form for use.
Regardless of technique, participants found the new material to be highly competent at increasing sheet thickness and uniformity at all measured points when comparing parts formed from the existing aluminum tool.
HYVAC-LCM is still a developmental material at CMT.