STUDY OF THREE START HELICAL ABRASIVE FLOW MACHINE FOR DUCTILE MATERIALS

Abstract

Abrasive flow machining (AFM) is a process that finishes complex internal and external geometries with the help of viscoelastic abrasive medium, while keeping in mind its low finish and material removal rates (MRR). Researchers have often strived to improve finishing rate and MRR. As an attempt to overcome the said limitations, this project report discusses Helical abrasive flow finishing (H-AFM) process where a three star helical drill bit is used coaxially with in the hollow cylindrical workpiece using three piece nylon fixture . The developed Helical-Abrasive flow machining process employs a standard helical drill-bit, which forces the abrasives laden media to follow a helical path within the finishing zone Curvature in the path of abrasives laden media, leads to development of centrifugal forces in the media in addition to a combination of different media flows (flow along the flute, axial flow, and scooping flow, and remixing of medium at exit from the finishing zone. For the present problem a three-start helical profile have been developed for the conduct of experiments and to study the effect of these on various response parameters. For the experimentation on the Helical-AFM setup, helical profile rod needs to be retained along the axis of the hollow cylindrical work-piece. The experimental design was according to an L9 orthogonal array based on the Taguchi method to study the effects of the helix rod and other main AFM process parameters. The main parameters are [type of materials Brass, Gun metal, and Mild steel] (M),Number of cycles (N), extrusion pressure (P), have been selected at three levels considering no-interaction among them. L9 orthogonal array based on the taguchi method has been used to study the effect of the helical drill bit and other main AFM process parameters. The main parameters are shape of the Type of material(M), Extrusion pressure (P), Number of cycles (N), has been selected at three levels considering no interaction among them.

A maximum improvement of 51.42% has been observed in the Surface finish. With the initial roughness 3.5 microns, an improvement to 1.70 microns has been observed on the inner cylindrical surface of the gunmetal work pieces.