Developing the polymer abrasive gels in AFM processs

Abstract

Abrasive flow machining (AFM) has excellent polishing effect in complex holes cut by wire electrical discharge machining (WEDM). The recast layers produced by WEDM can be removed when the abrasive media passes through the complex hole. Therefore, the media are the key elements that dominate the polishing behavior in AFM. However, commercial abrasive media are very expensive, and not every user can afford the prices. Lower-cost and effective abrasive media are developed to enhance the roughness of the WEDM surface in this research. Vinyl-silicone polymer (or silicone rubber) has good deformation and low flow effect; it can flow through the complicated holes easily. Moreover, the silicone rubber will not stick on the workpiece surface after machining. In this study, abrasive particles and silicone rubber are mixed uniformly to become the flexible media. Then a chain hole, cut by WEDM, is polished by these media in AFM. The abrasive medium with high viscosity has excellent deformation. It can easily polish the WEDM surface to a smooth finish. Furthermore, high abrasive concentration also has fine polishing result. In this research, the surface roughness decreases from 1.8 to 0.28 μmRa after five machining cycles (with abrasive concentration 60% (wt.%)). In this case, the roughness improvement rate (RIR) reaches 84%. On the other hand, small abrasive sizes can produce smoother surfaces than large abrasive sizes. But the polishing time might be several times longer than that by large abrasive sizes. However, the polishing efficiency is good when new abrasive media are used in AFM.