Pulsed laser ablation and incubation of nickel, iron and tungsten in liquids and air

Incubation effects in the nanosecond laser ablation of metals exhibit a strong dependence on the thermal and mechanical properties of both the target material and the background gas or liquid. The incubation in air is controlled mainly by thermal properties such as the heat of vaporization. In liquid, the correlation of the incubation and the ultimate tensile stress of the metals suggests that incubation may be related to the mechanical impact on the solid material by the cavitation bubble collapse, causing accumulation of voids and cracks in the subsurface region of the ablation craters. At high ultimate tensile stress, however, the low sensitivity to the environment suggests that the mechanical impact is likely to play a negligible role in the incubation. Finally, the correlation between the incubation and the carbon content of alcoholic liquids may be explained by an absorptivity increase of the cavity surfaces due to carbonaceous deposits generated by laser-induced pyrolysis, or by the mechanical impact of long-living bubbles at higher dynamic viscosity of liquids

The Development of CAD/CAM System for Automatic Manufacturing Technology Design for Part with Free Form Surfaces

Developed procedures for tool path generation and application representing a CAD/CAM system is presented in this paper. This application allows automatic manufacturing technology design for parts with free form surfaces for loaded CAD models of part and work piece in STL file format. Generated tool path will represent optimal tool path in accordance with multi criteria optimization methods. Developed application allows usage without any user's expertise in the field of CAD/CAM systems. The optimal tool path for manufacturing will be generated, which will be performed in the shortest time possible, having appropriate surface precision and quality. Developed procedures which are implemented in this system are the result of years of research in this field at the Department of Production Engineering, Faculty of Mechanical Engineering, University of Belgrade, Serbia. Also, development of cutting force model and experimental determination of cutting force coefficients for tool/work piece geometry and material combination is described. Research was conducted for combination of aluminium work piece and ball end mill of HSSE steel. The application is developed as a GUI interface, in MATLAB software. Mentioned application allows generation of NC codes for rough and finish machining for the tools stored in the application database. According to the generated NC codes, several parts were manufactured using the horizontal working centre in order to verify developed procedures for tool path generation and optimization. Based on the conducted experiment, it was concluded that the machining was performed in allowed tolerances and cutting conditions which confirm the usability of the developed software application