5. Ultrasonic Machining

Ultrasonic machining (USM), using shaped tools, high-frequency mechanical motion, and abrasive slurry is effective for materials of extreme hardness or brittleness. Unlike other nonconventional machining methods such as laser beam and electrical discharge machining, USM does not thermally damage the workpiece. This is important for the longevity of materials in service. However, the tool experiences wear, which causes a reduction machining efficiency. Composite materials offer advantages in structural applications because of their high specific strength and directional properties. In many applications, composites are cured in their final shape; however, machining is necessary at both the prepreg and product stages. In traditional drilling, delamination and splintering at the edges of holes often occur due to anisotropy and the lamination of composite materials. USM is suitable for such materials for its mode of material removal, which utilizes small individual abrasives. In this chapter, we discuss on-line tool-wear monitoring during USM, the effect of abrasive and drilling parameters on material removal rate, hole clearance, edge quality, tool wear, and surface roughness of composites for application in the manufacturing industry. This chapter shows that USM can provide greater profits than other nonconventional machining processes offer.