A Low-Viscosity, Recyclable Polymer-Based Binder Strategy for Metal FDM: Toward High Powder Loading, Sustainable...

Area of Science:

• Additive Manufacturing
• Materials Science
• Mechanical Engineering

Background:

• Metal fused deposition modeling (FDM) performance relies heavily on feedstock formulation, particularly metal solid loading.
• Binder selection in metal FDM faces challenges due to environmental concerns and limited recyclability.

Purpose of the Study:

• To develop and evaluate highly filled 17-4PH stainless steel feedstocks for FDM using a recyclable polymer binder.
• To determine the optimal metal powder loading for superior printability, structural integrity, and mechanical performance.

Main Methods:

• Formulation of 17-4PH stainless steel feedstocks with 93.0-96.0 wt.% metal powder using a paraffin wax and stearic acid binder.
• Rheological analysis to assess shear-thinning behavior and printing trials to evaluate print fidelity.
• Characterization of green parts, thermal debinding, sintering, and mechanical testing (UTS, elongation, tribocorrosion).

Main Results:

• Optimal shear-thinning behavior and extrusion stability were observed at 95.0-95.5 wt.% powder loading.
• 95.5 wt.% feedstock demonstrated superior print fidelity and structural integrity compared to lower or higher loadings.
• As-sintered parts from 95.5 wt.% feedstock achieved 96.5% relative density, 758 MPa UTS, 5.2% elongation, and improved tribocorrosion resistance.

Conclusions:

• A 95.5 wt.% metal loading is critical for high-performance 17-4PH stainless steel feedstocks in metal FDM.
• The developed low-molecular-weight polymer binder system enables highly filled, recyclable feedstocks with excellent properties.
• This research advances metal additive manufacturing by providing optimized feedstock formulations for improved part quality and performance.