Development of direct metal laser fabricating machine

Abstract

Examples are given to establish the experiment platform for studying the direct metal laser fabricating (DMLF) as a variant of selective laser sintering (SLS). Taking into account of the special requirements for DMLF, by means of the low power SLS machine (CO2, 50 W) and high power laser processing machine (CO2, 2000 W) in the authors' institute, the system integration of two machines is realised after the improvement or rebuilding of light route system, functional units, machinery and electrical system, and control software in the primary SLS machine. After the system integration, the direct metal laser fabricating machine with the laser power up to 1000 W has been developed successfully. At the same time, the primary functions or performances of both low power SLS machine and high power laser processing machine are preserved entirely. The material suitable for DMLF machine ranges from non-metal powders to metal powders, including polystyrene, polyamide, sands and a large number of metal powders. Primary results show that the ability for DMLF of Cu based powder is much better than that of Fe based powder. DMLF parts or materials have some characteristics different from conventional methods in microstructure, phase and microhardness. Sintering environment still need to be improved especially including the seal ability of prototyping cabinet and preheating equipment in DMLF machine. The academic application of DMLF machine is on its way. Metal samples based on copper and 316L powders can be fabricated with the relative density of about 80 and 100% respectively utilising developed DMLF machine. All of advantages of primary two machines are utilised fully after system integration. A novel modification of the freeform technique selective laser sintering machine via system integration is put forward in this paper, developing a direct metal laser fabricating machine suitable for both non-metal and metal materials successfully.