Optimizing metal part distortion in the material extrusion-thermal debinding-sintering process: An experimental and...

Area of Science:

• Materials Science
• Additive Manufacturing
• Process Engineering

Background:

• Thermal debinding-sintering is vital for metal injection molding (MIM) parts produced via material extrusion-based additive manufacturing (AM).
• Metal parts often suffer distortion and porosity during debinding, degrading mechanical properties.
• Slowing debinding reduces defects but increases processing time.

Purpose of the Study:

• To optimize the thermal debinding-sintering process for bronze/polylactide (PLA) parts to minimize distortion and porosity.
• To investigate the influence of crucible size, heating rates, and holding times on part quality.
• To employ computational fluid dynamics (CFD) for understanding temperature distribution during debinding.

Main Methods:

• Conducted debinding-sintering experiments using bronze/PLA filaments in small, medium, and large crucibles.
• Varied heating rates and holding times during the thermal debinding process.
• Utilized CFD simulations to analyze temperature profiles within the kiln for different crucible sizes.

Main Results:

• The small crucible showed higher initial porosity (23%), reducible to 12% with extended heating/holding times.
• The medium crucible achieved approximately 15% porosity without extended processing.
• The large crucible faced challenges in reaching target temperatures, limiting porosity reduction.

Conclusions:

• Combining experimental studies with CFD simulations offers a promising approach to enhance metal part quality in thermal debinding-sintering.
• Crucible selection and process parameter optimization are critical for mitigating defects in AM metal parts.
• The medium crucible presents an efficient option for reducing porosity in bronze/PLA parts without significantly increasing cycle times.