Progress on Tooling by 3D Printing; Conformal Cooling, Dimensional Control, Surface Finish and Hardness

Three Dimensional Printing is being applied to the direct fabrication of tooling using metal \npowders. This paper presents progress updates in four areas: i) thermal management using \nconformal cooling and related work on enhanced heat transfer using surface textures, ii) data on \ndimensional control, iii) ) improvements in surface finish, and iv) harder tooling. \nConformal cooling has demonstrated significantly improved performance in a production part \ngeometry with simultaneous gains in production rate and part quality obtained as measured against \nconventional tooling. Surface textures printed on cooling channels have demonstrated 8X \nenhancement of heat transfer over smooth channels. \nA set of 18 tooling inserts was fabricated using hardenable stainless steel powder with a \nresultant tooling hardness of 25-30 Rockwell C. Harder alloy systems are being designed with the \naid of computational thermodynamic tools which allow accurate prediction of the interaction of \npowder and binder. Significant improvements in surface finish were obtained using improved \nprinting technology. Dimensional control of tools conformed well to the expected result of being \ndominated by control of shrinkage and being predictable to within ±.25%.