Modeling and CFD Simulation of Abrasive Flow Machining Process

Abstract

The abrasive flow machining (AFM) is a new finishing operation that involves abrasive particles as the tool to remove work material. AFM is broadly known as “no-tool” precision finishing operation and the carrier media containing abrasive particles is called as “self-deformable stone”. In AFM, a semi-solid polymer-based media containing abrasive powders in a particular proportion is flown through the work-piece at a certain pressure. The AFM consists of three major components, i.e. machine, media and tooling or fixture. The machine consists of a frame structure, control system, hydraulic cylinder and the media cylinder. The extrusion pressure for a standard AFM process varies from 10 bars to 100-200 bars. The function of tooling and fixture is to position the work-piece and provide direction to the media flow through the work-piece. The media consists of a carrier, abrasive powder and some additives. The flow of the media can be modeled using finite volume method as it deals with flow of a fluid. In the present work, FLUID FLOW FLUENT available in ANSYS 15 software package was used for the modeling and simulation. A 2D model for a cylindrical work-piece and a 3D model for four rotary swaging dies along with the fixtures have been prepared. Validation has been done for the two models with the existing experimental data. The most affecting flow output parameters like dynamic pressure, velocity and strain rate for different volume fraction and media speed have been analysed. The 3D model was simulated for both the non-granular and granular flow. The effects of different abrasive particles for variable diameter and volume fraction on the flow output parameters like granular pressure and skin friction coefficient have been studied. The flow analysis of the outputs gives a prediction of material removal efficiency.