Drilling of polymer matrix composites: A review

Abstract

This article addresses the effects of drilling parameters on the machinability parameters in drilling polymeric composite materials. Drilling parameters include: feed, speed, drill wear, drill geometry, drilling with special tools, and composite materials parameters. The machinability parameters include: thrust force, torque, residual strength, surface roughness, and mechanical and thermal damages of the composite materials. Delamination associated with drilling processes can often be the limiting factor for composite materials in structural applications. It results in reducing the structural strength, poor assembly tolerance and, hence, it has the potential for long-term performance deterioration. Therefore, special interest will be given for reporting factors affecting the delamination onset, delamination mechanisms, measurements, assessments, and delamination-free techniques in drilling fiber-reinforced composites.

Cryogenic cooling-induced process performance and surface integrity in drilling CFRP composite material

“…It was also noted that tool-wear, high trust force, and torque that eventually affect the quality of produced hole are also considered as issues that need to be addressed [2][3][4][5]. In the literature, various cutting speeds [6], feed rate [3,7], drill bit geometries [8][9][10][11], tool coatings [12,13], and tool materials [14,7] have been proposed to minimize delamination in drilling of CFRP composite materials. Although it was reported that a majority of studies presented in the literature did not use any coolant and lubrication during drilling of CFRP composites [15], a few studies reported the positive effects of cooling and lubrication such as flood cooling [16] and MQL on drilling performance of this particular work material [17,18].…”

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

“…Although up to this stage, the temperature maxima was below T g of the CFRP, it may still lower the strength of the composites in the thickness direction [43,44] which could affect the drilling qualities. As such, it is believed that the existing mathematic models in CFRP machining (e.g., the popular critical thrust force models [3]) could be further refined for better damage prediction and control if the temperature characteristics derived from this study can be taken into account. The temperature began to fluctuate after passing its peak (see Fig.…”

“…However, CFRP belongs to hard-tomachine materials and is particularly sensitive to high temperatures. The machining process of CFRP is typically performed in a dry condition, as traditional coolants usually interact with CFRP physically and/ or chemically, leading to undesirable machining errors and weakened material bearing capacity [2][3][4]. Due to its low thermal conductivity and low specific heat capacity, heat can easily accumulate in CFRP cutting zone in the absence of coolant.…”

“…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.…”

“…[18,19,31], whereas infrared thermography [32,33] has been explored for non-contact measurement of temperatures with the infrared camera. In the drilling of CFRP, researchers have employed embedded thermal sensors on the flank faces of drills to monitor the temperature with varying processing parameters [3,6,34,35]. 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.…”