A hybrid material extrusion device with local debinding and sintering

Abstract

To date, debinding and sintering of parts fabricated through material extrusion (MEX) has been done in a time-consuming disconnected approach, with geometries initially shaped, then debinded and lastly sintered. Little progress has been made to process MEX bodies within the same device, eliminating part transportation to sophisticate and expensive equipment. This study shows that debinding and sintering in-situ, within the same volume, can be achieved efficiently by selectively applying local energy on the as-built green parts. A hybrid device is disclosed, combining traditional MEX with local debinding and sintering. The hybrid machine is integrated with a low intensity infrared diode laser and an induction heater, whereby the combination of concentrated energies during the manufacturing process can lead to near-net shaped geometries. The results establish that the main binder matrix of a Highly Filled (HF) stainless steel 316 L filament can be removed effectively across the entire 3D volume during the shaping stage. It is further reported that local sintering of debinded geometries results in high densities with short soaking times, being a promising improvement compared to conventional methods. Local thermal debinding and sintering allows to simplify the processing of MEX parts, avoiding the use of toxic agents and expensive post-processing equipment.