Laser Applied Rapid Prototyping of Metallic and Ceramic Dies

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In the proposed process, laser is scanned over the surface of metallic powders to make a wire, and then by making many wires in parallel with a gap a surface could be made. By adding the layrs, three dimensional model could be formed. At first CO_2 laser is scanned over various metal powders and the solidified features are observed. It is found that solidified blocks can be made with copper powders but many voids are left inside of the block. To reduce the voids, the powders are compacted and the initial density is increased. Although the voids are reduced by this method, much more energy is needed due to a greater heat transfer. From the simple analysis of solidification process, the forming characteristics are affected by the heat conductivity and the rate of laser absorption. To carry out finite element analysis, heat transfer coefficients of various metals with some densities are measured. By using the coefficients, the solidification behavior of the powders is simulated by the dev … More eloped finite element code. By using the finite element analysis, it is found that pulse laser with a high peak output is desirable, and pulse type YAG laser is employed for the next step and the materials suitable for this process is looked for. Since the process is considered to be a continuous cladding, Ni base and Cu base cladding materials are tested. By using the cladding materials, solidified wires with almost no voids are obtained. From the result of mechanical testing, the hardness numbers of the solidified Ni base alloys are about 800Hv and that of Co base alloy is about 600 Hv. Although the solidified Ni base alloy is brittle, it is improved by heat treatments. Finally a new method of forming a three dimensional die is proposed. Since a long time is needed to make a large body by this process, only the surface shell and the sustaining parts are to be made by laser prototyping and the remaining parts are filled by casting of lower melting point metals. The proposed method is ascertained by some simple shaped 3D models. Less