Development of high resolution laser wire directed energy deposition

Abstract

Among metal AM processes today, Laser Wire Directed Energy Deposition (Lw-DED) stands out as one promising technology for repair due to the high deposition rate, material efficiency, and good material properties, however, with relatively low resolution. Thus, there is a growing interest within industry to improve the resolution of the process in order to enable repair and manufacturing of smaller components without giving up the process advantages. This report describes the considerations and steps taken to design, produce, and evaluate a fine resolution Lw-DED tool. The tool features a set of linear axis coupled to a robotic arm used for fine control of the melt. The tool also features a variety of sensors which combined allow for implementing automatic control loops to avoid process issues. Tool evaluation was conducted by building thin walls on the edges of metal plates and bars on the face of plates. The built geometries were then inspected to compare to the net shape volume of the desired geometry and examined for lack of fusion defects. The test pieces produced with the tool were then compared against pieces produced with a more conventionally sized Lw-DED system. The tool demonstrates the ability to produce fully dense parts with a wall thickness of 1.6 mm and a layer height of 0.2 mm in 308 stainless steel. Thus enabling repair of components such as jet turbine blades or creation of miniature cooling channels on heat exchangers.