On the development of direct metal laser sintering for rapid tooling

An iron based powder blend has been developed for rapid tooling using a direct laser sintering process. The powder consists of a mixture of different elements including Fe, C, Cu, Mo and Ni. High sintering activities were obtained by tailoring the powder characteristics and optimizing the chemical constituents. The manufacturing of complex-shaped parts is possible at rates of 6.75 cm3/h according to CAD data. The residual porosity is less than 5 vol.%. The bending strength is around 900 MPa and the artifact hardness is 490 HV30. To further improve the service life of tools, the processed parts are sintered again in a vacuum furnace at 1260 °C for 30 min. This enables to manufacture precision parts with the density around 7.7 g/cm3 (sintering shrinkage is nearly zero). The dimensional accuracy of the sintered parts is improved by using a beam compensation technique that is integrated in the computer program of the laser sintering system. In this article the sintering behavior, mechanical properties, and microstructural features of the multi-component iron based powder are given and implications of the material for industrial applications are presented. A case study was performed to present the applicability of the material for rapid tooling.