Temperature effects in end milling carbon fiber reinforced polymer composites

Abstract

The temperatures at the cutting area rise excessively in machining of CFRP due to the low thermal conductivity of the material. And machining damages become aggravated with cutting-area temperatures approaching to the glass transition temperature of resin matrix. Therefore, controlling the cutting-area temperature at the suitable range is remarkably important for improving machining qualities. This article presented experimental investigations into cutting-area temperature influences on cutting force, surface integrity, as well as subsurface quality in end milling of multi-directional CFRP composites, and further discussed cutting mechanism variations. The cutting-area temperatures were controlled under three ranges by employing pressured cryogenic nitrogen gas and no coolants. The machining quality under low temperature in general was better than that under high temperature. Particularly, morphologies under high temperatures indicated fibers were bended to fracture resulting in severe subsurface damages. In contrast, the hardened matrix at low temperatures offered fibers better support, and the composites were easily squeezed to rupture which led to superior cutting performance. However, as the temperature reached extremely low, the cutting force increased dramatically and then could reduce tool life. Thus the suitable temperature range is proposed for the first time in machining CFRP. POLYM. COMPOS., 00:000-000,

The Effects of Cutting Parameters on Tool Wear During the Milling of CFRP Composites

“…Increased wear values were observed as a result of the effect of the heat and friction at cutting tool-workpiece interface. The heat arising from machining of CFRP material softens the matrix material which weakens the adherence between fiber reinforcements, thus increasing tool wear [26].The highest wear value was detected with 0.05 mm/tooth feedrate in machining of CFRP composite with uncoated carbide insert. Wear values were found to decrease with increasing cutting speed, which was also associated with the machining time.…”

Surface grinding of carbon fiber–reinforced plastic composites using rotary ultrasonic machining: Effects of tool variables

“…47 The higher temperature may lead to some resin soften, resulting in larger surface roughness. 7,61 Another possible reason was that the increase in contacting force F x caused the increase in load of the cutting tool, leading to the increase in the rate of tool wear. The CFRP composites were not sharply cut, resulting in the increase in surface roughness.…”

Drill-exit temperature characteristics in drilling of UD and MD CFRP composites based on infrared thermography

“…The difference could be attributed to that the temperature characteristics were dependent on the measurement method as well as the actual drill/CFRP cutting interactions. In the previous studies [7,9,14,24,36], researchers deployed the thermocouple to measure the temperature from inside of a workpiece. However, as compared to the bulk inner materials, the materials at the drill-exit surface suffered from more severe deflections/ damages due to the lack of constraint, therefore different temperature characteristics can be expected.…”

“…Particularly, in traditional drilling [3] as well as ultrasonic drilling of CFRP [5], the relatively enclosed manufacturing environment with poor ventilation is inevitable and will always lead to a rapid increase of the temperature, probably exceeding the glass transition temperature (T g ) of CFRP (approximately 160-200°C) [6][7][8]. As a result, the high temperature in CFRP machining would soften the resin matrix [3,9] and even results in thermal degradation during a short aging period, compromising the CFRP mechanical properties [10][11][12][13]. In addition, the drill exit of a hole, subjected to large deflection without back support and constraint, is the most susceptible area to damages such as delamination, splintering and burr.…”

“…Due to the unique thermal properties of tool material and CFRP, and different heat distributions in tool, workpiece and chips, the measured temperature can only represent the average temperature within a wide zone rather than the specific temperature of the machined surface. In other cases, thermocouples were embedded both inside and outside the hole periphery for temperature detection at the tool-workpiece interface, or placed outside the hole to capture the temperature characteristics of the overall CFRP drilling process [7,9,14,24,36]. However, as the sensor's position is much restricted spatially by the experiment layout, it is difficult to obtain sufficient and accurate temperature data to reveal the comprehensive temperature characteristics at drill exit.…”