Improved manufacturing processes with high power lasers

Abstract

The first part of this paper gives a general idea of overall trends and points of importance for the different laser applications. Some new interesting laser processes have been proposed but have not reached a significant industrial exploitation up to now. Reasons for industrial acceptance of laser processes are explained. Process improvements are discussed on the example of laser cutting and machining of cacities. Both applications are characterized by a high speed gas jet. For the material removal processes the influence of the nozzle design for the assisting gas flow is investigated. Numerical simulations of the gas flow are carried out and compared with Schlieren photos. Normal jet impingement of newly designed nozzles and conventionally used nozzles is compared at various nozzle stand off distances. In order to calculate shock wave locations and strengths correctly the Navier Stokes equations in finite volume form have been modified. Furthermore supersonic effects in the cut kerf are investigated. The importance of quality and process control is shown and discussed for the removal processes. For machining of cavities an appropriate depth controller is of main importance for an industrial exploitation. This process is discussed in detail and the problems for designing a closed loop controller are explained. Furthermore an industrial in-process sensor for laser cutting is presented, which allows to supervise the cut quality.