Laser cutting of carbon fiber-reinforced plastic with an absorber transparent for visible spectrum

Mass production of carbon fiber-reinforced plastic parts has lately started in the automotive industry. Due to no abrasive wear in combination with a high degree of automation and ability for 3D processing, laser remote cutting is a suitable method for machining purposes in this context. In the automotive environment, solid-state lasers are favored because optical waveguides may then be used. In turn, the low absorption of the radiation of such lasers in the matrix material presents a drawback in terms of comparatively large heat affected zones (HAZ) and flaking at the cutting kerf. This paper deals with the question, if a laser absorbing additive can be used to enhance the absorption within the matrix material, while the optical properties in the visible spectrum are kept. For this purpose, an additive known from laser transmission welding has been added to the matrix material. Cutting experiments have been carried out while varying concentration of the additive. The investigations show that a significant reduction of the mean HAZ of 25% and the standard deviation (1 σ) of 56% can be achieved by adding 4% w/w of the additive to the resin. In addition to that, the flaking behavior can be avoided. Compared to adding soot particles, the optical properties of the laminate do not change in the visible spectrum, leaving the fiber textile visible.