Parameter selection in laser welding using the power factor concept

To achieve specific penetration depths in laser welding particular combinations of laser power and travel speed are required. Different combinations of power and travel speed can be used to obtain the same penetration depth. Further, for a given combination a different penetration depth occurs if a different beam diameter is used. Beam diameter is controlled by the laser properties and the optical system, and varies between laser systems. This causes difficulties in both selecting optimum laser parameters for a given application and in transferring parameters between laser systems. This can be greatly simplified using the power factor concept. Power factor is defined as the product of intensity and beam diameter. Plots of constant penetration depth as a function of power factor and interaction time can be generated and these are independent of beam diameter. Using this concept, system parameters can be selected based on criteria defined by users, such as productivity, process efficiency or heat input. A suitable laser system for that application can then be specified. It also allows transfer of laser parameters between systems. This approach will be illustrated by the use of some specific examples.