Development of Laser-based Directed Energy Deposition System with Non-Pneumatic Powder Feedstock Handling and Synthesis of Toolpath Strategies

Abstract

Pneumatic methods of powder feedstock handling are prevalent in laser-based Directed Energy Deposition (DED). These methods use inert gases (mostly Argon) to meter, convey, and inject powder feedstock into the melt pool created by the laser on the substrate. Although several variants of pneumatic feedstock handling exist in the literature, the difference is mainly in the mechanism of powder metering and the geometric design of the powder delivery nozzle. This work identifies several shortcomings of such pneumatic-based feedstock handling systems and offers an easy solution that could be more economical. A gravity-based system, proposed as part of this study, has been demonstrated to be a viable replacement for pneumatic methods. The gravity-based non-pneumatic system utilizes a helical-grooved shaft rotating inside a powder-filled hopper to meter the mass flow rate. This metered influx of powder is subsequently delivered to the powder delivery nozzle, which creates a conical and convergent envelope of powder stream around the fusion source before finally injecting it into the melt pool.