Title: Workpiece surface integrity and productivity when cutting CFRP and GFRP composites using a CO₂ laser

Authors: I.S. Shyha; Chun-Liang Kuo; S.L. Soo

Addresses: Department of Mechanical and Construction Engineering, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, UK; Production Engineering Department, Faculty of Engineering, Alexandria University, 21544 Alexandria, Egypt ' Machining Research Group, School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK ' Machining Research Group, School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK

Abstract: Following a brief literature review, results from tests involving laser cutting of carbon and glass fibre reinforced plastic (CFRP and GFRP) composites are presented. The influence of cutting speed, laser beam power and gas pressure on material removal rate (MRR), kerf width and workpiece surface integrity were investigated. Productivity was up to ~100% higher when cutting GFRP compared to CFRP, with a maximum MRR of ~8 cm³/min achieved when operating at a cutting speed of 1750 mm/min, 2500 W beam power and gas pressure of 5 bar. Charring and melting of the matrix phase was observed in both materials and similarly surface voids/cavities were evident on the CFRP and GFRP samples. Three-dimensional topographic maps also revealed the presence of grooves on the latter, which would explain the significantly higher surface roughness levels obtained (up to ~13µm Ra). Heat affected zones were visible in the majority of CFRP specimens assessed which extended to a depth of ~1.5mm (depending on the fibre orientation) while only minor damage in terms of fibre protrusion was apparent in corresponding GFRP workpieces. Kerf widths decreased with increasing cutting speed and were typically over 2 times larger in the GFRP material.

Keywords: laser cutting; surface topography; material removal rate; MRR; workpiece damage; surface integrity; CFRP composites; GFRP composites; carbon fibre reinforced plastic; glass fibre reinforced plastic; cutting speed; laser beam power; gas pressure; surface roughness; surface quality.

DOI: 10.1504/IJMMS.2014.064746

International Journal of Mechatronics and Manufacturing Systems, 2014 Vol.7 No.2/3, pp.93 - 107

Received: 10 Dec 2013
Accepted: 11 Feb 2014
Published online: 21 Oct 2014 *

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