Dieter Schuocker - Böcker

The European Community regards training as a priority area and has therefore developed a series of programmes in the field of vocational training. This book is the result of a pilot project selected under two of these Community Action Programmes. It was initially selected under the COMETT programme, concerned with the development of continuing vocational training in the European Community. Moreover, it was one of the few selected projects to receive further funding under a second selection in the context of the LEONARDO DA VINCI Action Programme for the implementation of a European Community Vocational Training policy. It is with great pleasure that I present the outcome of this project which embodies one of the fundamental objectives of the LEONARDO DA VINCI Programme -training for new technologies in SMEs, which make a significant contribution to economic development in Europe. K DRAXLER Director Directorate General XXII European Commission x Acknowledgements The Volume Editor gratefully acknowledges funding by the LEONARDO DA VINCI Programme of the Commission of the European Community and by the Austrian Federal Ministry of Science and Transport whose financial support has made the EuroLaser Academy a reality and has led directly to the generation ofthis handbook. He is also indebted to Director Dr. Klaus Draxler, Head of the LEONARDO DA VINCI Programme, DG XXII of the Commission of the European Community, moreover to Director General Raul Kneucker, Minister's Advisor Helmut Schacher and Mrs. Friederike Pranckl-Kloepfer from the Austrian Federal Ministry of Science and Transport.

If in some processes oxygen is used, additional energy is provided at a rate P ch by chemical reactions. The flow of energy per unit time can then be written: (1. 2) From the above it can be made clear that it is the rate of energy fluxes, i. e. 2 intensities [J/ms] that determines into which channel the energy goes and how the interaction zone will be modified in its state (solid, liquid, gaseous) and geometrical shape (plane, dip, deep hole) -in other words which kind of treatment process will be established (hardening, welding, drilling etc. ). In the following, it will be shown that, in fact, it is the intensity of the beam, which together with the interaction time, primarily governs the interaction phenomena. 1. 1. 2 Laser beam properties determining interaction and energy coupling etJeets In order to yield an efficient process, it is necessary to obtain adequate intensity at the workpiece and to couple a fraction of the incident power as high as possible into the material. The beam properties being of importance in this respect are, (Hugel, 1992): 1. the wavelength A. , governing, in principle, the focusability and absorptivity; 2. the polarisation, having considerable influence on the absorptivity for large angles of incidence; 3. the power P which together with the achievable spot diameter d L f determines the intensity in the interaction zone; 4.

The European Community regards training as a priority area and has therefore developed a series of programmes in the field of vocational training. This book is the result of a pilot project selected under two of these Community Action Programmes. It was initially selected under the COMETT programme, concerned with the development of continuing vocational training in the European Community. Moreover, it was one of the few selected projects to receive further funding under a second selection in the context of the LEONARDO DA VINCI Action Programme for the implementation of a European Community Vocational Training policy. It is with great pleasure that I present the outcome of this project which embodies one of the fundamental objectives of the LEONARDO DA VINCI Programme - training for new technologies in SMEs, which make a significant contribution to economic development in Europe. - K DRAXLER, Director Directorate General XXII European Commission

High power lasers of either the gas or solid state type can be used to generate a focal spot with a diameter of about a tenth of a millimetre and a power density of up to 100 Mio W/cm2. With these intensities all materials can be heated up rapidly, leading to fast melting, violent evaporation or even plasma formation. So laser beams can be utilized for various processing tasks, such as transformation hardening, cutting and ablation or welding and cladding or even rapid prototyping. With these processes, important advantages are achieved compared to conventional tools such as high processing speed due to the high concentration of energy and high quality of the processed workpiece without deformations due to the small overall heat input to the workpiece that corresponds to the small spot diameter. All these advantages finally result in strongly reduced production costs, which is the main reason for a world-wide substitution of conventional processes and other beam tools by laser technology.This monograph offers a great insight into the operation principles of high power laser sources, the phenomena of interaction of laser beams and materials and the mechanisms of the various production processes with lasers — thus enabling production engineers and others to make optimum use of the benefits of laser technology and to understand the technical properties and the physical limitations of this most recent technology (especially in comparison to conventional tools and other beam tools), and providing a sufficient basis for the understanding and use of future developments in this area.