Post-processing of additively manufactured microstructures using alternating-magnetic field-assisted finishing

Abstract

Complex-shaped components with unique microstructural features are becoming more and more important in the section of the optics and aerospace industries. Currently, additive manufacturing (AM) has been acknowledged as a potential technology to fabricate complex-shape components for the industrial application. However, the poor surface quality limits the performance of the AM components. This work was focused on the post processing for the 316L rectangular microstructures fabricated by the selective laser melting (SLM) technique. A novel alternating-magnetic field-assisted finishing (A-MFAF) method was proposed to improve the surface quality of rectangular microstructures while maintaining the surface profile accuracy. The magnetic field generator was designed to integrate two permanent magnet poles with different magnetization directions and a slotted magnetic pole holder. The alternating magnetic field of the finishing tool was thus achieved in the finishing zone. Finite element analysis (FEA) was utilized to verify the feasibility of the magnetic field generator. The material removal principle of the A-MFAF method was introduced in detail. Mathematical models of the material removal ratio (MRR) were established. The effects of finishing parameters on surface roughness were evaluated quantitatively. Experimental results showed that the 316L materials were uniformly removed from the top to the bottom surface of the rectangular microstructures. The SLM-generated surface defects were removed as well. Surface roughness (Sa) of the top and bottom surfaces was reduced from initial 9.79 μm to 0.85 μm and 3.12 μm, respectively. After finishing, the residual stress was converted from tensile to compressive states.

Keywords

• Surface finishing
• Selective laser melting (SLM)
• Microstructure
• Magnetic field-assisted finishing
• Surface quality