Recent developments showed that micro extrusion of feedstock can be used for manufacturing metallic micro bi- lumen tubes of very high length-to-diameter aspect ratios which are not viable by conventional metal extrusion or commonly used feedstock processing technologies like injection moulding or hot pressing. The extrusion of high aspect ratio micro components faces the challenge of maintaining the geometrical accuracy, surface finish and structural properties as the micro extrusion in green-state is followed by debinding and sintering operations which result in shrinkage and variations in surface finish and structure. The stages of the process chain such as solvent/thermal debinding, to remove the polymeric binder, and pre-sintering, to achieve a mild structural rigidity before the part sintering, are critical stages in achieving the surface and structural properties in case of high aspect ratio micro parts and are not yet studied in case of micro extrusion of feedstock. In this study, the effect of debinding and pre-sintering on surface and structural properties of bi-lumen tubes processed at different extrusion conditions are discussed. Surface roughness of the tubes is analysed using 3D microscopy and structural properties are studied using scanning electron microscopy (SEM) and electric discharge spectroscopy (EDS). The debinding and pre- sintering experiments on extruded micro bi-lumen tubes retained very good surfaces without any cracks or defects. The study showed that interactions of extrusion temperature and extrusion velocity influence the surface finish of the extruded tubes the most. The sintered bi-lumen samples showed a good areal surface finish, Sa of 2.21 μm which is near to the green-state value confirming the suitability of the applied debinding and pre-sintering parameters.

Debinding and Pre-Sintering of High Aspect Ratio Micro Bi-Lumen Tubes Produced by Extrusion of 17-4PH Feedstock

Sandeep Kuriakose;Salvatore Cataldo;Paolo Parenti;Massimiliano Annoni
2019

Abstract

Recent developments showed that micro extrusion of feedstock can be used for manufacturing metallic micro bi- lumen tubes of very high length-to-diameter aspect ratios which are not viable by conventional metal extrusion or commonly used feedstock processing technologies like injection moulding or hot pressing. The extrusion of high aspect ratio micro components faces the challenge of maintaining the geometrical accuracy, surface finish and structural properties as the micro extrusion in green-state is followed by debinding and sintering operations which result in shrinkage and variations in surface finish and structure. The stages of the process chain such as solvent/thermal debinding, to remove the polymeric binder, and pre-sintering, to achieve a mild structural rigidity before the part sintering, are critical stages in achieving the surface and structural properties in case of high aspect ratio micro parts and are not yet studied in case of micro extrusion of feedstock. In this study, the effect of debinding and pre-sintering on surface and structural properties of bi-lumen tubes processed at different extrusion conditions are discussed. Surface roughness of the tubes is analysed using 3D microscopy and structural properties are studied using scanning electron microscopy (SEM) and electric discharge spectroscopy (EDS). The debinding and pre- sintering experiments on extruded micro bi-lumen tubes retained very good surfaces without any cracks or defects. The study showed that interactions of extrusion temperature and extrusion velocity influence the surface finish of the extruded tubes the most. The sintered bi-lumen samples showed a good areal surface finish, Sa of 2.21 μm which is near to the green-state value confirming the suitability of the applied debinding and pre-sintering parameters.
Proceedings of the World Congress of Micro and Nano Manufacturing 2019
micro extrusion, debinding, pre-sintering, bi-lumen tube, surface quality, feedstock
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/1106472
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