Effect of Unconventional Machining on Surface Roughness of Metal: Aluminum and Brass- A Case Study of Abrasive Flow

Abstract

Abrasive finishing techniques are developed to overcome the problems such as high direct labor cost and to produce finished precision parts with specific features for finishing inaccessible areas. Abrasive finishing is carried out with a large number of cutting edges, which have indefinite orientation and geometry. Abrasive fine finishing processes are commonly employed because of their inherent capabilities of finishing various geometries of form, (i.e., flat surface, round surface, etc), and various geometries of surface relation (i.e. parallelism, squareness, straightness, angularity, etc.), with the desired dimensional accuracy and surface finish. In AFM, the medium gently and uniformly scrape the surfaces and/or edges, whereas it is not so in the case of grinding. In grinding, abrasives are held rigidly by hard (solid) bond material, whereas in AFM abrasives are held by semisolid bond (or medium). In all these abrasive finishing processes, the grain-workpiece interaction involves one or more of the basic modes of material deformation, i.e., cutting, ploughing and rubbing. Basically cutting is a material removal process, ploughing is a material displacement process and rubbing / sliding is a surface modification process. The key components of AFM process are the machine, tooling and abrasive medium. Process input parameters such as extrusion pressure, number of cycles, grit composition and type, tooling and fixture designs have impact on AFM output responses (such as surface finish and material removal). AFM is capable to produce surface finish (Ra) as good as 0.05 ?m, deburr holes as small as 0.2 mm and radius edges from 0.025 mm to 1.5mm. AFM has wide range of applications in industries such as aerospace, medical, electronics, automotive, precision dies and moulds as a part of their manufacturing activities.