Laser polishing 3D metallic surfaces with an optical pre-shaping device leads to a constant surface quality

While there is an increasing demand for flexible polishing solutions for industrial applications, most of the parts with freeform surfaces and function relevant edges must be polished manually. But manual polishing is time consuming and incurs high personnel costs.

Automating the polishing process with continuous laser wave radiation, which is suitable for many 3D parts, is one method to deal with these challenges. Judith Kumstel reports an approach for keeping the beam geometry constant on the workpiece regardless of the angle of incidence.

“The resulting constant surface quality on 3D surfaces is a decisive milestone for laser polishing and is also of interest for other laser surface processing methods,” said Kumstel.

Laser polishing of 3D surfaces often leads to a non-perpendicular angle of laser incidence. This results in a projection of the focused circular laser beam on the surface of the workpiece that is primarily approximated with an elliptical shape with accompanying reduced intensity and deteriorated roughness.

The researchers aim to develop a method to keep the surface quality constant when laser polishing a 3D surface with a non-perpendicular angle of incidence. They used an optical preshaping device to maintain the circular symmetry of the laser spot on the workpiece and to ensure a constant polishing quality.

The next step will be to integrate preshaping optics into a 3D laser polishing system and process real 3D components with it.

“This approach is also suitable for many other 3D laser surface processing methods, such as laser hardening, where it is important to keep the laser parameters constant,” said Kumstel.

Source: “Laser polishing of metallic freeform surfaces by using a dynamic laser beam preforming system,” Judith Kumstel, Journal of Laser Applications (2021). The article can be accessed at https://doi.org/10.2351/1.5128459 .