Drilling is involved in many applications of carbon fiber-reinforced plastic (CFRP) composites. Rotary ultrasonic machining (RUM) has been successfully employed to drill holes in CFRP using either cutting fluid or cold air as coolant. However, there are no reported studies to compare the results in RUM of CFRP using these two types of coolant. This article, for the first time, presents an experimental study to compare cutting force, torque, surface roughness, burning of machined surface, and tool wear in RUM of CFRP using these two types of coolant. This study will result in knowledge about machining conditions under which it is feasible to use cold air instead of cutting fluid and differences in machined hole quality produced using cold air vs. cutting fluid.
Rotary ultrasonic machining (RUM) has been successfully used to drill Ti (titanium and its alloy), CFRP, and CFRP/Ti stacks. In all studies on RUM reported in the literature, feedrate was fixed during each experimental test. It has been shown that low feedrate should be used for RUM of Ti, but RUM of CFRP could be done using feedrate ten times higher. This paper, for the first time, reports a study on RUM of CFRP/Ti stacks using variable feedrate (high feedrate for CFRP and low feedrate for Ti). It also makes comparisons on RUM of CFRP/Ti stacks using fixed and variable feedrate.RUM CFRP-Ti Stacks (Text) 3
Carbon fiber reinforced plastic (CFRP) composites are in demand for a variety of applications due to their superior properties. Drilling is involved in many CFRP applications. Experiments have been successfully conducted to use rotary ultrasonic machining (RUM) for CFRP drilling. These experiments were conducted using either cutting fluids or cold air as coolant. RUM of CFRP composites without cutting fluids can eliminate problems caused by cutting fluids, such as high cost of cutting fluids and their disposal, pollution to the environment, and harm to human health. However, dry machining (machining without cutting fluids) also has its limitations, such as burning of machined surface, more friction and adhesion between tool and workpiece, and reduction in tool life. This article presents an experimental study on feasible regions in rotary ultrasonic machining of CFRP using cold air as coolant. Three criteria (burning of machined surface, delamination, and tool blockage) were used to determine feasible regions. Each of four input variables (feedrate, tool rotation speed, ultrasonic power, and cold air pressure) was changed over a wide range so that its feasible region could be found.
Abstract:Drilling is involved in many applications of carbon fiber reinforced plastic (CFRP) composite. Twist drilling is widely used in industry. Rotary ultrasonic machining (RUM) has been successfully tested to drill holes in CFRP. However, there are no reports on comparisons between RUM and twist drilling of CFRP. This paper compares RUM and twist drilling of CFRP in six aspects (cutting force, torque, surface roughness, delamination, tool life, and material remove rate). Experimental results show that RUM is superior in almost all these aspects.
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