Journal of Materials Processing Technology 89 – 90 (1999) 198 – 203 Parametric studies on pulsed Nd:YAG laser cutting of carbon fibre reinforced plastic composites Jose Mathew a, *, G.L. Goswami b , N. Ramakrishnan c , N.K. Naik d a Department of Mechanical Engineering, R.E.C., Calicut, Kerala 673 601, India b Atomic Fuels Diision, Bhabha Atomic Research Centre, Mumbai 400 085, India c Department of Mechanical Engineering, I.I.T., Powai, Mumbai 400 076, India d Department of Aerospace Engineering, I.I.T., Powai, Mumbai 400 076, India Received 15 September 1998 Abstract Carbon fibre reinforced plastic (CFRP) composites are found to be cut satisfactorily by a pulsed Nd:YAG laser at the optimum process parameter ranges. Predictive models have been developed based on important process parameters, viz. cutting speed, pulse energy, pulse duration, pulse repetition rate and gas pressure. The responses considered are the heat-affected zone (HAZ) and the taper of the cut surface. The optimisation of process parameters was done using response surface methodology (RSM). The thermal properties of the constituent material and the volume fraction of the fibres are the principal factors that control the cutting performance. The effect of the process parameters on the output responses is also discussed. © 1999 Published by Elsevier Science S.A. All rights reserved. Keywords: Composites; Fibre reinforced plastics; Laser cutting; Response surface methodology 1. Introduction Fibre reinforced plastic (FRP) materials are one of the most widely used composite materials for structural applications, particularly for aerospace structures. Properties such as high specific strength, specific stiff- ness and ease of tailoring to a specific need make them attractive. As the cost of these materials is continually declining, they are finding ever-increasing applications in all fields. Even though near-net manufacturing of composite materials is possible, drilling will remain an unavoidable operation, particularly in assembly. Drilling of FRP composites using conventional tools produces problems such as delamination, fibre pull-out and tool wear [1,2]. Laser cutting, being a non-contact process, does not involve any mechanical cutting forces and tool wear. However, as laser cutting is based on the interaction of a laser beam with the composites, defects that are thermal in origin may arise if proper care is not taken regarding the selection of the cutting parameters ranges [1–7]. Most of the researchers who did experimental analy- sis with composite materials have used the method of varying one-factor-at-a-time to determine the effect of process parameters on the responses [1 – 7], but usually this technique is not only inefficient but also unsuccess- ful, as it fails to determine interactions [7–9]. It is felt that a systematic study with statistically planned exper- imentation using response surface methodology (RSM) will give more insight into such situations. RSM allows all main effects as well as interactions to be evaluated with the minimum number of experiments. Also, math- ematical models correlating the output with the input process parameters can be obtained. 2. The workpiece material Woven fabric carbon fibre reinforced plastic (CFRP) composites of 2 mm thickness were used for conducting the studies. The reinforcing material used was T300 * Corresponding author. Fax: +91-495-287250. E-mail address: josmat@vishak.reccal.ernet.in (J. Mathew) 0924-0136/99/$ - see front matter © 1999 Published by Elsevier Science S.A. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 9 9 ) 0 0 0 1 1 - 4