Dimensional accuracy control for complex components of high-strength titanium alloys by metal injection molding

High-strength titanium alloy hinge components with complex geometry were fabricated by metal injection molding (MIM). The dimensional characteristics of these components were systematically evaluated under various processing conditions by optical and three-dimensional imaging instruments. The influences of degreasing methods, part orientation, molding techniques, and binder systems (specifically plastic-based and wax-based binders) on the dimensional accuracy and shape stability of the components were investigated. The results show that, compared with the wax-based injection green parts, the plastic-based injection green parts have the higher strength, which are less prone to deformation during debinding, and exhibit the higher dimensional stability of the sintered parts. During the debinding stage, the wax-based injection green parts could produce a “swelling” phenomenon, resulting in lower dimensional accuracy than that of plastic-based injection green parts. During the sintering stage, the dimensional precision can be further enhanced by optimizing part orientation and adjusting the surface roughness of sintering plates. Ultimately, through the sintering fixtures and post-molding reshaping treatments, the dimensional accuracy of MIM-fabricated titanium alloy components can be controlled within ±0.1%.