Rheological characterization of newly developed fly-ash mixed polymeric media and its finishing performance through abrasive flow machining

Abstract

One of the essential requirements for efficient performance and longer service life of machined components is a good surface finish. Though there are other traditional finishing processes like lapping, grinding, and honing. However, the major disadvantage associated with them is, they can process only simple geometry. Abrasive flow machining (AFM), due to its self-deforming characteristic, is used for finishing parts having predominantly irregular geometry. All AFM processes comprise a machine, fixture, and media (i.e., carrier/or putty mixed with abrasive particles) among which, media (viscoelastic polymer) plays a dominant role. The commercial abrasive, which is one of the constituents of the viscoelastic media for AFM, which provides the finishing action (abrasion), are very expensive and hence it is a major problem for the small industries. Also, the finishing cost per unit component (workpiece) with a commercial media having SiC/diamond abrasives turns out to be very high, which makes its use uneconomical for mass finishing. Therefore, in the present research work, an attempt has been made to develop an alternative low-cost AFM media by replacing commercial abrasives with waste coal fly-ash. The developed media are characterized through static and dynamic rheological tests, thermogravimetric analysis, and finishing experiments on aluminum and mild steel workpieces to judge the performance of newly developed media concerning the traditional one. The percentage improvement obtained in average surface roughness(ΔRa) through fully fly-ash-based media (68% fly-ash) is ~56% for the aluminum and ~49% for mild steel workpieces.

Keywords

• Abrasive flow machining
• Rheology
• Fly-ash
• Viscoelastic media