What is Reduced Model

Laser based cutting processes comprise a significant part of industrial manufacturing. To ensure a high level of cutting quality the process parameters have to be kept at the right values and within defined tolerances. In this context, the position of the laser beam focus is one of the most important parameters. However, due to thermal heating of optical elements the focal position shows a transient behavior. The handling of this focus shift is aggravated by the fact that the focal position is not directly detectable during processing. In this chapter an introduction in the topic of laser cutting is given. Subsequently, a closed mathematical formulation of laser fusion cutting is presented before a reduced model is developed that allows the determination of a focus shift by an experimentally accessible surrogate criterion. The theoretical predictions are finally validated by experimental results.