Laser machining in lamellar cast iron

Today, the laser machining is commonly used in micromachining. As a matter of fact laser allows surfaces to be textured with small dimensions in a wide range of applications. This work presents different laser surface textures machined in a heterogeneous material. The structure can be lines, dimples or prisms. The ratio between the width and the depth of the textured forms has been set to 10, with a depth about 10 µm. As the textured material was lamellar cast iron which is a heterogeneous material, the laser machining parameters need to be set precisely in order to obtain the desired dimensions of the grooves with a sufficient accuracy. In addition to the power adjustment of the laser, the machining strategy has to be determined experimentally with the aim to reach a high level of surface roughness quality. This goal can be achieved by tilting the galvanometric scanner allowing the laser beam to be tilted up to 20° [1]. In addition, to improve the quality of the laser machining, a laser polishing can be made thanks to an offset between the focal point of the laser beam and the surface [2]. Consequently, the metal is just melted and the Ra roughness parameter can be decreased. At least in order to characterize the laser patterned surface, an InfiniteFocus® topomicroscope has been used. A microscope is combined with a camera allowing 3D images to be acquired. By means of an area color focus sensor and thanks to a motorized table, the camera shoots a set of images of the sample at different focusing depths. For each image, the software compares the contrast of each point with its neighbors and builds a 3D image by means of these points. Such data sets allow optical image, topographic image, profile, surface, volume to be obtained.