Surface Polishing of Laser Powder Bed Fused Inconel 625 Surfaces Using Multi-jet Hydrodynamic Cavitation Abrasive Finishing: An Emerging Class of Cleaner Surface Enhancement Process

• Published in: International journal of precision engineering and manufacturing-green technology 2023-05, Vol.10 (3), p.637-657
• Main Authors: Nagalingam, Arun Prasanth, Toh, Boon Loong, Yeo, Swee Hock
• Format: Article
• Language: English
• Subjects: Abrasive cleaning; Abrasive finishing; Abrasives; Cavitation; Cost control; Efficiency; Lasers; Manufacturing; Manufacturing industry; Metal fatigue; Nickel base alloys; Polishes; Polishing; Powder beds; Superalloys; Surface layers; Synergistic effect; Viscoelasticity; Working fluids
• ISSN: 2288-6206; 2198-0810
• DOI: 10.1007/s40684-022-00471-7

Polishing the laser powder bed fused (L-PBF) components and achieving uniform roughness is exceptionally challenging. Moreover, retaining the dimensional integrity of intricate features during polishing is difficult. This research aims to overcome these issues by developing a novel multi-jet hydrodynamic cavitation abrasive finishing (MJ-HCAF) approach for polishing the complex L-PBF components. The technique proposed in this article uses cavitation principles as a constructive tool for polishing hard-to-machine materials within 10 min. A new industrial-scale apparatus was developed to realize the proposed concept. L-PBF Inconel 625 surfaces were polished to demonstrate the MJ-HCAF technique's effectiveness. The MJ-HCAF technique resulted in up to ~ 85% improvement in surface texture quality (final Sa ≤ 0.5 µm; Sz ≤ 10 µm). Moreover, the final appearance was controlled to glossy or matt polish to suit aerospace aesthetic requirements. The proposed technique uses water as the primary working fluid with abrasives ≤ of 1.0% to generate a polished surface (conventional abrasive-based methods use 60–80%)—indicating an emerging class of cleaner manufacturing process. The Product Sustainability Index (PSI) for a sustainable approach showed that cavitation-assisted abrasive polishing mode has the highest PSI score of 7.88. The key factors leading to its high score are its synergistic effects, low-cost water operation, and extremely low abrasive usage.