Numerical simulation of two-dimensional wick debinding in MIM by body fitted finite element method

Thermal debinding in metal powder injection moulding(MIM) is an intricate p henomenon. An alternative description of wick debinding in the 2D compact-w ick material combination is developed here by numerical simulation. To simp lify the problem and to qualitatively investigate the wick debinding proces s, the assumptions of a single component binder and fully saturated compact with molten binder are adopted. As the flow of molten binder is a moving b oundary phenomenon, which is similar to a fluid flowing through porous medi a, a new numerical technique, body fitted FEM, is used to generate grids in side the physical domain and to calculate the distributions of pressure and other relative properties. Results show that the predictions of debinding time versus compact thickness squared and the debinding rate agree well wit h those issued by German and Vetter et al., respectively; this identifies t he reliability and accuracy of the present numerical analysis. Low Reynolds number Re and low capillary number Cn indicate that capillarity is more do minant than effects such as inertial force, viscous force, etc. Though high permeability of the wick can increase the artery of the draining compact, the capillary pressure will decrease with the larger pores. The shape of th e flow front of the molten binder and the outer geometry of compact are fou nd to be closely matched in the final step of wick debinding. PM/0839 (C) 1 999 IoM Communications Ltd.