Rotary Ultrasonic Machining of CFRP: Effects of Abrasive Properties

Drilling is the most common machining practice conducted on carbon fiber reinforced plastics (CFRP), which is challenging to conventional machining processes, such as twist drilling. Rotary ultrasonic machining (RUM) is a non-traditional machining process that has been successfully used to drill CFRP, many other brittle (e.g. silicon, ceramics), and ductile (e.g. titanium alloy (Ti-6Al-4V), stainless steel) materials. RUM is superior to twist drilling on CFRP hole-making in many aspects: lower cutting force and torque, better surface finish, less potential for delamination, and better tool life. Since RUM is a hybrid process of abrasive grinding and ultrasonic machining, it is important to study the effects of abrasive properties on output variables. This paper for the first time investigates the effects of abrasive properties (abrasive size and abrasive concentration) on output variables (cutting force, torque, and surface roughness) in RUM of CFRP. It is found that cutting force increased as abrasive size increased and as abrasive concentration increased; however, abrasive properties did not have significant effects on surface roughness of the machined holes.