22 - Fly ash-mixed polymeric media for abrasive flow machining process

Abstract

Precise manufacturing technology always demands excellent surface finish at a low cost. Presently there are many techniques available for surface finish, and one among them is the abrasive flow machining (AFM) process. The process utilizes a semisolid abrasive laden media to polish surfaces, deburr holes, radius edges, and remove the recast layer from the surface of the component. The performance of AFM can be improved by changing or augmenting the setup of AFM with other different processes. However, the performance can also be improved by tailoring the type and constituents of the abrasive laden medium. The constituents of the medium are very costly especially the commercial abrasives, which are generally silicon carbide (SiC), cubic boron nitride, aluminum oxide, and diamond particles. Considering the industrial demands, in this chapter, the authors present the idea of utilizing waste coal fly ash as abrasive in the fabrication of AFM medium in place of costly abrasives like SiC, diamond, etc. The rheological characterization of the various fly ash filled abrasive medium shows improved flow properties as compared to full SiC medium. Further, the actual AFM experimental assessment of the various composition of fly ash media was carried out on three materials, namely, mild steel, aluminum, and En-24 steel. The percentage improvement in surface finish obtained by full fly ash media is 56%–54% for Al and En-24 material samples, respectively, for 600 cycles. Though in the case of the mild steel sample, the improvement in surface finish obtained by full fly ash media is a little inferior to the result obtained by full SiC medium. The price of SiC abrasives cannot be overlooked; they are much costlier than waste fly ash. Hence the overall cost and performance point of view of the fly ash media provides a technically viable and economically affordable alternative for AFM media. At the same time, utilization of waste fly ash as abrasive in AFM media for finishing purposes alleviates the disposal issue of fly ash and resolves the problem of high-cost AFM media by replacing the most expensive constituent of the media, which is the abrasive.