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The paper reports an experimental study of die-casting dies with conformal cooling fabricated by direct-metal additive techniques. The main objective is to compare the benefits and limitations of the application to what has been widely discussed in literature in the context of plastics injection molding.Selective laser melting was used to fabricate an impression block with conformal cooling channels, designed according to part geometry with the aid of process simulation. The tool was used in the manufacture of sample batches of zinc alloy castings, after being fitted on an existing die in place of a machined impression block with conventional straight-line cooling channels. Different combinations of process parameters were tested to exploit the improved performance of the cooling system. Test results show that conformal cooling improves the surface finish of castings due to a reduced need of spray cooling, which is allowed by a higher and more uniform cooling rate. Secondary benefits include reduction of cycle time and shrinkage porosity. KeywordsSelective laser melting; rapid tooling; die casting; conformal cooling; spray cooling; surface finish. 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 Title pageClick here to download Manuscript: titlepage.doc Click here to view linked References 1 2 3 4 5 6 7 8 SLM tooling for die casting with conformal cooling channels AbstractThe paper reports an experimental study of die-casting dies with conformal cooling fabricated by direct-metal additive techniques. The main objective is to compare the benefits and limitations of the application to what has been widely discussed in literature in the context of plastics injection molding.Selective laser melting was used to fabricate an impression block with conformal cooling channels, designed according to part geometry with the aid of process simulation. The tool was used in the manufacture of sample batches of zinc alloy castings, after being fitted on an existing die in place of a machined impression block with conventional straight-line cooling channels. Different combinations of process parameters were tested to exploit the improved performance of the cooling system. Test results show that conformal cooling improves the surface finish of castings due to a reduced need of spray cooling, which is allowed by a higher and more uniform cooling rate. Secondary benefits include reduction of cycle time and shrinkage porosity.

Percutaneous replacement of the pulmonary valve is a recently developed interventional technique which involves the implantation of a valved stent in the pulmonary trunk. It relies upon careful consideration of patient anatomy for both stent design and detailed procedure planning. Medical imaging data in the form of two-dimensional scans and three-dimensional interactive graphics offer only limited support for these tasks. The paper reports the results of an experimental investigation on the use of arterial models built by rapid prototyping techniques. An analysis of clinical needs has helped to specify proper requirements for such model properties as cost, strength, accuracy, elastic compliance, and optical transparency. Two different process chains, based on the fused deposition modelling technique and on the vacuum casting of thermoset resins in rubber moulds, have been tested for prototype fabrication. The use of anatomical models has allowed the cardiologist's confidence in patient selection, prosthesis fabrication, and final implantation to be significantly improved.

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PurposeTest the detail resolution of fused deposition modeling (FDM) in the direct manufacture of rapid prototypes with textured surfaces.Design/methodology/approachA benchmark part carrying regular surface patterns with different feature sizes and aspect ratios has been manufactured on a FDM system with different build orientations. Layered parts have been inspected to detect the occurrence of quality defects on textured surfaces.FindingsThe experiments reveal the ability of currently available FDM systems to enhance prototype surfaces with form details on a millimeter scale. Results assist in identifying conditions which need to be satisfied in order to successfully reproduce generic texture geometries.Research limitations/implicationsAlthough the testing method can be applied to any layered manufacturing technique, results are limited to a specific process, and may be influenced by technical improvements of commercial fabrication systems.Practical implicationsA first contribution is given to a full feasibility assessment of direct texturing, which potentially appears as more responsive and cost‐effective solution than current post‐finishing practices.Originality/valueThe paper proposes a systematic approach to the manufacture of textured parts by rapid prototyping techniques. The analysis of surface appearance in the presence of small‐scale form details adds a novel aspect to current approaches to performance benchmarking, which typically focus on form errors and roughness of plain surfaces.

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