Control of the quality of laser surface texturing

Since the conception of the first lasers in the 60’s, the knowledge and consequently the applications of laser have been widely increased. Laser surface texturing is a specific field among the various applications of the laser. This technique is employed in the aim of improving tribological performances for instance. This paper presents the laser surface texturing of a heterogeneous material. This material is lamellar cast iron. It has been chosen for its good friction properties. The textured surface is composed of grooves or dimples. The dimensions are micrometric. For the grooves, different cross sections have been engraved: semicircular, rectangular, trapezoidal and triangular. The dimples are cylindrical. All these laser textured surfaces are engraved with the laser manufacturing machine: DML 40 SI of Gildemeister (Germany). This machine is equipped with a galvanometric scanner, which allows tilted surfaces to be engraved. Various machining strategies and the following results are discussed in function of the different desired laser surface texturing results. In addition, to increase the aspect of the engraved surfaces, laser polishing is employed. Thanks to a defocalisation of the laser beam on the surface, the material is not ablated but melted. To be able to compare the different laser machining process, several techniques of control have been used: roughness profilometry, scanning electron microscopy and non contacting optical measurement. The rules of use of these methods must be defined bearing in mind their inherent limitations.