On the prediction of hole geometry in laser trepanning drilling: A generic 3D analytical model considering drill system structure

Laser trepanning drilling is a widely used manufacturing technology for creating holes in thin-walled parts or difficult-to-cut materials due to its exceptional efficiency and versatility with various material types. Although there have been several experimental studies on laser trepanning, a comprehensive understanding of the relationship between system layout, laser beam alignment, and produced hole geometries is still lacking from a theoretical perspective. To address this, a generic model for the typical four-wedge trepanning drilling system was proposed in this paper. This model allows for analytical calculation of the full laser trajectory in the 3D spatial domain, enabling prediction of drilled hole geometries such as diameter and taperness. Experimental verification of the laser trajectory and machined hole geometries was conducted through a series of trials to validate the proposed model. Based on this validated model, interesting phenomena were discussed, such as the effect of initial optomechanical system conditions on the hole geometries, and the effects of laser parameters on the hole circularity. With this, the proposed model aims to provide a solid theoretical foundation for understanding laser trepanning drilling technology in terms of system design and process optimization.