Abstract
Carbon fibre-reinforced polymer (CFRP) composites have found wide applications in the aerospace, marine, sports and automotive industries owing to their lightweight and acceptable mechanical properties compared to the commonly used metallic materials. Machining of CFRP composites using lasers can be challenging due to inhomogeneity in the material properties and structures, which can lead to thermal damages during laser processing. In the previous studies, Nd:YAG, diode-pumped solid-state, CO2 (continuous wave), disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge. In this paper, a short-pulsed (8 μs) transversely excited atmospheric pressure CO2 laser was used, for the first time, to machine CFRP composites. The laser has high peak powers (up to 250 kW) and excellent absorption by both the carbon fibre and the epoxy binder. Design of experiment and statistical modelling, based on response surface methodology, was used to understand the interactions between the process parameters such as laser fluence, repetition rate and cutting speed and their effects on the cut quality characteristics including size of HAZ, machining depth and material removal rate (MRR). Based on this study, process parameter optimization was carried out to minimize the HAZ and maximize the MRR. A discussion is given on the potential applications and comparisons to other lasers in machining CFRP.
Highlights
Composite materials such as Carbon fibre-reinforced polymer (CFRP) composites have distinct advantages over conventional materials
Nd:YAG, diode-pumped solidstate, CO2, disc and fibre lasers were used in cutting CFRP composites and the control of damages such as the size of heat-affected zones (HAZs) remains a challenge
The analysis of variance (ANOVA) results for cross-sectional HAZ indicate that the fluence, A, the scanning speed, C, and the quadratic terms B2 and C2 are significant terms
Summary
Composite materials such as CFRP composites have distinct advantages over conventional materials. A carbon fibre-reinforced polymer consists of higher-strength abrasive fibres bonded within a weak polymer. This structure is heterogeneous and anisotropic depending on the constituent’s physical properties, fibre orientation and laminar arrangement. CFRP composites are more difficult to machine than conventional materials generally because they are heat sensitive and the carbon fibres are very abrasive [4]. The machining process can significantly affect these materials, leading to various forms of damages, such as delamination, fibres pull-out and heat damages. This can result in components being rejected at the last stage of their production sequence [5]. Mechanical machining of CFRP composites often leads to excessive tool wear and delamination (e.g. Fig. 1) on fibre
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