Solid Freeform Fabrication technologies have demonstrated the potential to produce tooling with cooling channels, which are conformal to the molding cavity. 3D Printed tools with conformal cooling channels have demonstrated simultaneous improvements in production rate and part quality as compared with conventional production tools. Conformal cooling lines of high performance and high complexity can be created, thus presenting a challenge to the tooling designer. A systematic, modular approach to the design of conformal cooling channels is presented. Cooling is local to the surface of the tool, so the tool is divided into geometric regions and a channel system is designed for each region. Each channel system is itself modeled as composed of cooling elements, typically the region spanned by two channels. Six criteria are applied, including: a transient heat transfer condition, which dictates a maximum distance from mold surface to cooling channel; considerations of pressure and temperature drop along the flow channel; and considerations of the strength of the mold. These criteria are treated as constraints, and successful designs are sought that define windows bounded by these constraints. The methodology is demonstrated through application to a complex core and cavity for injection molding.

Ta-N thin film is an attractive interlayer as well as a diffusion barrier layer in [Fe-N/Ta-N] n multilayers for the application as potential write head materials in high density magnetic recording. We synthesized two series of Ta-N films on glass and Si substrates by using reactive radio frequency sputtering under 5 mtorr Ar/N 2 processing pressure with varied N 2 partial pressure, and carried out systematical characterization analyses of the films. We observed clear changes of phases in the films from metallic bcc Ta to a mixture of bcc Ta(N) and hexagonal Ta 2 N, then sequentially to fcc TaN and a mixture of TaN with N-rich phases when N 2 partial pressure increased from 0.0% to 30%. The changes were associated with changes in the grain shapes as well as in the preferred crystalline orientation of the films from bcc Ta [100] to [110], then to random and finally to fcc TaN [111], correspondingly. It was also associated with a change in film resistivity from metallic to semiconductor-like behavior in the range of 77K-295K. The films showed typical polycrystalline textured structure with small, crystallized domains and irregular grain shapes. Clear preferred (111) stacks parallel to the substrate surface with embedded amorphous regions were observed in the film. TaN film with [111] preferred orientation and a resistivity of 6.0 mΩ•cm was obtained at 25% N 2 partial pressure, which may be suitable for the interlayer in [Fe-N/Ta-N] n multilayers.

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