Abstract
Due to the continually increasing popularity of metal powder-based additive manufacturing as a production process in recent years, there has been growing research into improving the surface quality of the parts manufactured in this way. Laser polishing offers great potential as a finishing technique due to its flexibility and suitability for automation. However, the complexity of components that can be produced with additive manufacturing processes presents challenges in developing practical and flexible arrangements for implementing a laser polishing process. In this paper, we offer methods to manage height variations of parts using weakly focused beams, process components that are (roughly) cylindrical using rotational stages, and polishing of internal surfaces using simple optics. As an example application, we present finishing of additively manufactured cobalt chrome dental implants to a surface roughness of 0.45 μm in only 60 s using a low-cost fiber delivered diode array laser.
Highlights
Laser polishing is a surface processing technique to improve surface finish using a high-power laser beam
The complexity of components that can be produced with additive manufacturing processes presents challenges in developing practical and flexible arrangements for implementing a laser polishing process
We present finishing of additively manufactured cobalt chrome dental implants to a surface roughness of 0.45 μm in only 60 s using a low-cost fiber delivered diode array laser
Summary
Laser polishing is a surface processing technique to improve surface finish using a high-power laser beam. In 2015, Flemmer et al.[11] reported an “industry ready” laser polishing machine capable of finishing glass moulds offering polishing rates of 40 s cm−2 compared with up to 5 min cm−2 for manual polishing while increasing the hardness of the metal improving mould lifetime.[11,12] This is achieved by using a 5-axis machine along with a 3-axis laser scanner and complex control software to reduce incidence angles preventing elliptical beams. A telescope system is used to generate a laser spot with a long depth of focus to minimize spot size variations on the laser beam incident on the surface; second, the use of rotation stages is demonstrated for cylindrical parts to allow for a continuous process and reduce stitching effects; and third, internal surface polishing without direct line of sight is demonstrated using right-angled prisms. To highlight the improved working range of the two approaches, shaded regions are included representing beam diameters of 400 ± 100 μm, W(z) 1⁄4 W02sffi1ffiffiffiþffiffiffiffiffiffiffiffiZffiffizffiRffiffiffiffiffiffi2ffi,
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