Study on direct laser metal deposition

Abstract

In the current economic situation with worldwide trend for developing new products, the importance of time and cost reduction increases day-by-day. To achieve this goal the man-machine-material interaction should be maximized. Direct laser metal deposition (DLMD) is one of the most famous approaches for this. DLMD is one kind of 3D printing technology (Additive Manufacturing) together with laser cladding process. In DLMD, it is possible to fabricate fully functional metallic parts directly from CAD data, which involves a feeding of metal powders through a nozzle into a high power laser beam and creates a melt pool on the surface of the solid substrate upon which a metallic powder is injected. DLMD process are now acknowledged worldwide and is also known to all by several other names such as Laser metal deposition (LMD), Direct laser deposition (DLD), Laser engineered net shaping (LENS), Direct light fabrication (DLF), Laser deposition welding (LDW) and powder fusion welding (PFW). The role of nozzle in this process is as important as the heart of a human being. There are verity of nozzle configurations namely off-axis, continuous coaxial and discontinuous coaxial powder injection. Comparison of these types towards specific applications revels very interesting observations which are subsequently reproduced in this article. In DLMD, laser beam and powder metals are fed through the nozzle onto a metallic substrate. Then, powder melts by the laser heat and creates a metal pool on the solid substrate by fusion bonding. Once the feedback control sensor gives feedback of completion of deposition of a layer, the laser head, along with the powder delivery nozzle, move up. The whole process is carried out until final near-net-shape of the metal part or component is achieved with a variety of material applicability area and high quality clad track deposition with good mechanical properties. After development of this process in 1995, lot of researchers for several years work on various aspects of high quality deposition with dimensional accuracy such as good clad geometry, clad height, and microstructure study of the mechanical properties. Through this paper on the basis of literature survey an attempt has been made to focus on proper selection of the set up configuration for direct laser metal deposition to fulfill the requirement and helps to achieve high quality deposition.