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Rapid manufacturing of complex NiTi parts from metal powders and polymer binders

NiTi shape memory alloys exhibit interesting mechanical properties, but also poor formability and machinability. Wide applications of SMAs needs efficient manufacturing techniques, especially net-shape solutions.

The aim of this project is to establish the feasibility of manufacturing complex NiTi parts by three-dimensional printing. The parts have been grown by additive layer-by-layer processes, by joining metal powder particles with a polymer binder. The printing step is followed by thermal debinding and sintering in controlled atmosphere. Two routes have been explored: a) printing parts with a ProMetal 3D-printer, which drops binder on powder beds, and b) printing parts with a laboratory printer, which drops solvent on metal-polymer granule beds. Appropriate conditions for layer deposition, printing, debinding and sintering have been established.

3D-printed NiTi specimens exhibit shape memory behaviour. The feasibility of processing complex net-shape prototypes, with good green strength and shape preservation after sintering has been assessed. Further research is necessary to evaluate and improve sintered part properties, dimensional stability, and test functionality.

 

Shape-memory effects measured in NiTi processed
by solvent on granule printing

NiTi part processed by 3D-printing