Experimental and analytical investigation of solvent debinding of copper via material extrusion additive manufacturing

The iteration of additive manufacturing (AM) of metals has evolved both direct approaches like powder bed fusion and indirect approaches, including material extrusion, stereolithography, etc. The indirect AM technologies for metals typically utilise an intermediate carrier, e.g., thermoplastic or photopolymer, as binders. The shaping is merely a physical or chemical process of the intermediate binder, which significantly mitigates the manufacturing cost. However, a subsequent debinding step becomes necessary to remove the binders and obtain pure metal components. This research studied the most commonly applied solvent debinding method for metal pieces printed with filament-based material extrusion (MEX). Analytical models were developed based on the diffusion principle to predict the progression of binder removal (i.e., weight loss) as a function of time and dimension. Besides, the models were fit with experiment results and proved a strong match. Furthermore, the effect of incomplete solvent debinding on the subsequent thermal debinding was also investigated. By combining the analytical model and the weight loss threshold for thermal debinding, the whole process time can be significantly optimized to reach maximum manufacturing efficiency.