The Importance of Material Structure in the Laser Cutting of Glass Fiber Reinforced Plastic Composites

A previously proposed micromechanical formula, aiming to predict the vaporization energy Q_v of composite materials as a function of fiber and matrix properties and fiber volume ratio, was assessed. The experimental data, obtained on glass fiber reinforced plastic panels with different fiber contents cut by a medium power CO₂ cw laser, were treated according to a procedure previously suggested, in order to evaluate Q_v. An excellent agreement was found between experimental and theoretical Q_v values. Theory was then used to predict the response to laser cutting of a composite material with a fiber content varying along the thickness. The theoretical predictions indicated that, in this case, the interpretation of the experimental results may be misleading, bringing to errors in the evaluation of the material thermal properties, or in the prediction of the kerf depth. Some experimental data were obtained, confirming the theoretical findings.