Development and performance evaluation of galactomannan polymer based abrasive medium to finish atomic diffusion additively manufactured pure copper using abrasive flow finishing

Abstract

Abrasive flow finishing (AFF) is an advanced finishing process where the surface roughness of the component is gradually reduced by reciprocating an abrasive medium. A typical abrasive medium consists of base polymers, rheological additives, and abrasive particles. In most cases, the base polymer chains are based on siloxane, natural or synthetic elastomers, thermoplastic polymers, etc. The abrasive media developed with these polymer chains are expensive, and most of them are not biodegradable. In the recent past, hydrogel-based abrasive media gained significant attention as it results in a cost-effective, eco-friendly, and biodegradable abrasive medium. Since water is the main constituent in these media, this may cause corrosion of the component surfaces. Due to the high shear strain rates involved in the AFF process, the hydrogel-based media quickly lose moisture and becomes dry; thus, the life of the media reduces. In the present work, a long-lasting and noncorroding abrasive medium was indigenously developed for the AFF process. This medium constitutes galactomannan polymer, glycerol solution, cross-linker, and abrasive particles. The developed medium was absolutely free from expensive rheological modifiers. In addition to the rheological characterization, the developed medium was characterized using scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. The finishing performance of the developed media was assessed by finishing atomic diffusion additively manufactured (ADAM) pure copper curved samples. The effect of the number of finishing cycles, extrusion pressure, and abrasive mesh size was investigated on the amount of material removed and the percentage change in average surface roughness (Ra). A reduction of Ra up to 90% in the longitudinal direction and 75% in the transverse direction was obtained using the developed abrasive medium. Based on the obtained finishing results, the material removal mechanism from the ADAM surface was proposed.