A novel polyvinyl alcohol/guar gum hydrogel-based fluid abrasive for abrasive flow machining with enhanced processing performance

Selective laser melting (SLM)-fabricated components often exhibit high surface roughness and inherent surface defects, necessitating efficient post-processing. Hydrogel-based fluid abrasives are environmentally friendly alternatives for abrasive flow machining (AFM). However, traditional hydrogel matrices are generally based on polysaccharide polymers and suffer from limited mechanical strength and poor thermal stability, leading to water loss during processing, which restricts their practical application. To overcome these limitations, this study develops a novel polyvinyl alcohol-guar gum (PVA-GG) hydrogel-based fluid abrasive for the AFM of SLM-fabricated surfaces. In this system, the PVA provides mechanical load-bearing capacity, while the GG enhances viscoelasticity, jointly forming a tightly entangled network structure. The fluid abrasive was systematically characterized in terms of viscoelasticity, self-healing properties, thermal stability, and degradability, and its process performance was evaluated during the finishing of SLM-fabricated GH4169 alloy flow channels. The PVA-GG fluid abrasive shows significantly higher viscosity and modulus, with a weight loss of only 9.09 % below 100 °C. It also demonstrates remarkable self-healing properties and degradability. After AFM processing, the surface roughness ( Ra ) of the workpiece can be reduced by 90 %, and the material removal rate ( MRR ) reaches 0.43 mm³ /min, outperforming conventional fluid abrasives. Material removal in PVA-GG fluid abrasive is achieved through the combined actions of sliding, plowing, and micro-cutting. This study provides an efficient, sustainable, and mechanism-based approach for the precision surface finishing of SLM-fabricated components.