Fast Desktop-Scale Extrusion Additive Manufacturing

Abstract: Significant improvements to the production rate of additive manufacturing (AM) technologies are essential to their cost-effectiveness and competitiveness with traditional processing routes. Moreover, much faster AM processes, in combination with the geometric versatility of AM, will enable entirely new workflows for product design and customization. We present the design and validation of a desktop-scale extrusion AM system that achieves far greater build rate than benchmarked commercial systems. This system, which we call FastFFF, is motivated by our recent analysis of the rate-limiting mechanisms to conventional fused filament fabrication (FFF) technology. The FastFFF system mutually overcomes these limits, using a nut-feed extruder, laser-heated polymer liquefier, and servo-driven parallel gantry system to achieve high extrusion force, rapid filament heating, and fast gantry motion, respectively. The extrusion and heating mechanisms are contained in a compact printhead that receives a threaded filament and augments conduction heat transfer with a fiber-coupled diode laser. The prototype system achieves a volumetric build rate of 127 cm3/hr, which is 7-fold greater than commercial desktop FFF systems, at comparable resolution; the maximum extrusion rate of the printhead is ~14-fold greater (282 cm3/hr). The performance limits of the printhead and motion systems are characterized, and the tradeoffs between build rate and resolution are assessed and discussed. The combination of high-speed motion and high deposition rate achieved by the FastFFF technology also poses challenges and opportunities for toolpath optimization and real-time deposition control. High-speed desktop printing raises the possibility of new use cases and business models for AM, where handheld parts are built in minutes rather than hours.