Creating movable interfaces by micro-powder injection moulding

Abstract

This paper presents a novel in-situ technique to produce articulated components with highprecision, micro-scale movable interfaces by micro-powder injection moulding (μPIM). The presented process route is based on the use of micro-scale sacrificial layer between the movable subcomponents which is eliminated during the debinding step, creating a dimensionally-controlled, micro-scale mobile interface. The fabrication technique combines the advantages of micro-powder overmoulding, catalytic debinding and sintering. The demonstrated example was a finger bone prosthesis joint consisting of two sub-components with an interface between components of 200 μm in size. The geometries of the subcomponents were designed such that they are inseparable throughout the process whilst allowing them to move relative to each other after the debinding stage. The components produced showed the feasibility of the process route to produce readily-assembled meso-, and potentially micro-, scale articulated systems.

Effect of Thermal Debinding Conditions on the Sintered Density of Low-Pressure Powder Injection Molded Iron Parts

“…In conventional high-pressure powder injection molding (HPIM), the binder, which consists of a blend of low-and high-molecular-weight polymers (also called primary and secondary binders, respectively), is removed in two steps. During the first step, the primary binder is extracted either by a solvent [8][9][10], a supercritical fluid such as supercritical carbon dioxide [11,12], or a catalyst such as highly concentrated nitric acid [13,14], depending on the binder system and powder characteristics. During the second step, the secondary binder, acting as a backbone to retain the shape, is removed during a final burnout cycle before the sintering process [15,16].…”