Copper additive manufacturing using MIM feedstock: adjustment of printing, debinding, and sintering parameters for processing dense and defectless parts

Gurminder Singh,Jean-Marc Chaix,Didier Bouvard,Jean-Michel Missiaen

doi:10.1007/s00170-021-07188-y

Abstract

In the present study, an additive manufacturing process of copper using extrusion 3D printing, solvent and thermal debinding, and sintering was explored. Extrusion 3D printing of metal injection moulding (MIM) feedstock was used to fabricate green body samples. The printing process was performed with optimized parameters to achieve high green density and low surface roughness. To remove water-soluble polymer, the green body was immersed in water for solvent debinding. The interconnected voids formed during solvent debinding were favorable for removing the backbone polymer from the brown body during thermal debinding. Thermal debinding was performed up to 500 °C, and ~ 6.5% total weight loss of the green sample was estimated. Finally, sintering of the thermally debinded samples was performed at 950, 1000, 1030, and 1050°C. The highest sintering temperature provided the highest relative density (94.5%) and isotropic shrinkage. Micro-computed tomography (μCT) examination was performed on green samples and sintered samples, and qualitative and quantitative analysis of the porosity confirmed the benefits of optimized printing conditions for the final microstructure. This work opens up the opportunity for 3D printing and sintering to produce pure copper components with complicated shapes and high density, utilizing raw MIM feedstock as the starting material.

Highlights

The rapidly growing additive manufacturing (AM) processing has simplified the fabrication of complex and customized shapes with different metals [1,2,3,4]
The melted feedstock is strongly sheared inside the extruder, and the formation of voids may result from the resulting complex state of stress and from the variation of viscosity as the filament spreads out of the nozzle and solidifies on the deposited layers
The 3D metal printing and sintering of dense copper starting with metal injection moulding raw material was studied. 3D extrusion printing, solvent and thermal debinding, and sintering steps were performed to achieve copper samples with high relative density and minimal defects

Summary

Introduction

The rapidly growing additive manufacturing (AM) processing has simplified the fabrication of complex and customized shapes with different metals [1,2,3,4]. Some methods combine polymer 3D printing and other conventional manufacturing processes such as casting, sintering, electroforming, and spraying [8,9,10,11,12,13]. This opens the way to the fabrication of metal parts at low cost due to less capital investment, less material consumption, and low-skilled worker requirements. These techniques, those involving sintering, are beneficial to materials like copper, challenging to process by LBM and EBM. Owing to the high thermal and electrical conductivities of copper, combined with reasonable mechanical strength, AM-fabricated, complex-shape copper parts may be profitable in various engineering applications, such as actively cooled vehicle skin, power generators, heat exchangers, induction heat coils, radio frequency cathodes, bearings, parts with complex internal cooling channels, and efficient electronic thermal management structures

Methods

Results

Conclusion