PRELIMINARY-STUDY OF ULTRASONIC DRILLING OF FIBER-REINFORCED PLASTICS

Composite materials posses advantages in structural application thanks to thier high specific strength and directional properties. Although in many applications, composites are cured to final shape, machining can be required at both the prepreg and product stages In traditional drilling, due to the anisotropy and the lamination of composite materials, delamination and splintering at hole edge often occur. Ultrasonic machining is suitable for these materials for its nature of material removal. by small individual abrasives. Experiments were conducted on the ultrasonic drilling of Carbon/Epoxy and Carbon/PEEK. The examination of surfaces and abrasives after machining illustrates the hammering and impact of the abrasive particles on the workpiece. Bridle fracture of fibers and plastic deformation of matrix are seen. The research highlighted the influence of the concentration of abrasives, the size of abrasive grains, the energy of ultrasonic oscillation and the feed rate of tool on the machinability in respect of material removal rate, surface roughness and hole clearence. Dimensional analysis synthesizes the significant parameters in machining. Ultrasonic machining produced better surface finish and hole quality than conventional drilling. The cost factors of ultrasonic machining, investment,annual revenue, annual expenditures, economic life and salvage value are analyzed with annual and present worth methods. It shows that ultrasonic machining can earn higher profit than other non-conventional machining processes.