Hybrid Manufacturing Process for rapid high performance tooling combining High Speed Milling and Laser Cladding

Since the first introduction of rapid prototyping in the 1980's, several techniques have been developed and successfully commercialized. However, most commercial systems currently use resins or waxes as the raw materials. Thus, the limited mechanical strength for functional testing is regarded as an obstacle towards broader application of rapid prototyping techniques. To overcome this problem, direct metal deposition methods are being investigated worldwide for rapid prototyping and even for rapid tooling applications. As a contribution to this development a fundamental study on a process combination of laser cladding technology using YAG laser radiation with high speed milling was carried out and is reported in this paper. The design of the machining centre as well as the hybrid process are introduced. Solutions for upgrading of existing milling centres with a laser and subsystems needed to perform laser cladding, are discussed. As part of the hybrid process the cladded tool is milled every few cladding layers so that very small cutters can be used to reach every part of the tools surface before the next layers are added. Small milling cutters can be used to mill very small corner radii so that the hybrid machining concept will be capable of replacing electro discharge machining (EDM) on many tools. To realize complex parts and overhangs a 5-axis cladding process is needed. This paper presents a procedure and software prototype through which NC tool paths for laser cladding of complex parts on 5-axis machines can be directly generated from a CAD model. It will be possible to manufacture complex structures of fully dense metal and multiple materials. It will be shown that using 5-axis machining for laser cladding allows welding of features that can so far only realized using selective laser sintering in a bed of powder. In combination with the proposed hybrid concept it will be possible to manufacture the most complex and accurate parts. In conclusion, the advantages and disadvantages of this process are discussed. Sample parts e.g. copper alloy parts, nickel-base alloy parts will also be presented.