Non-Diffractive Bessel Beams for Ultrafast Laser Scanning Platform and Proof-Of-Concept Side-Wall Polishing of Additively Manufactured Parts.

Huu Dat Nguyen,Nicolas Faure,Cyril Mauclair,Razvan Stoian,Jean-Philippe Colombier,Xxx Sedao,Enrique Moreno,Guillaume Bidron

doi:10.3390/mi11110974

Abstract

We report the potential use of non-diffractive Bessel beam for ultrafast laser processing in additive manufacturing environments, its integration into a fast scanning platform, and proof-of-concept side-wall polishing of stainless steel-based additively fabricated parts. We demonstrate two key advantages of the zeroth-order Bessel beam: the significantly long non-diffractive length for large tolerance of sample positioning and the unique self-reconstruction property for un-disrupted beam access, despite the obstruction of metallic powders in the additive manufacturing environment. The integration of Bessel beam scanning platform is constructed by finely adapting the Bessel beam into a Galvano scanner. The beam sustained its good profile within the scan field of 35 × 35 mm. As a proof of concept, the platform showcases its advanced capacity by largely reducing the side-wall surface roughness of an additively as-fabricated workpiece from Ra 10 m down to 1 m. Therefore, the demonstrated Bessel–Scanner configuration possesses great potential for integrating in a hybrid additive manufacturing apparatus.

Highlights

Additive manufacturing (AM) is a cutting-edge technology that relies on builds-up of consecutive layer-by-layer parts for fabricating complex three-dimensional (3D) objects [1]
We report the potential use of the Bessel beam for ultrafast laser processing in additive manufacturing environment, its integration into a fast scanning platform, and proof-of-concept side-wall polishing of additively manufacture parts
An ideal zeroth-order Bessel beam is defined as the beam whose electric field (E) is explicitly described by the zeroth-order Bessel function of the first kind (J0) [37,38]: E(r, φ, z) = A0 J0(krr)ejkzz where A0 is the amplitude of the electric field; kz and kr are longitudinal and radial wavevectors, with k = k2z + k2r = 2π/λ is the wavenumber in air at the wavelength λ; z, r, and φ are the longitudinal, radial, and azimuthal components, respectively

Summary

Introduction

Additive manufacturing (AM) is a cutting-edge technology that relies on builds-up of consecutive layer-by-layer parts for fabricating complex three-dimensional (3D) objects [1]. The technology enables the transfer of digital designs to direct production of near-net shaped objects. It thereby offers great enhancement over the degree of freedom regarding shape complexity when compared to traditional subtractive manufacturing [2,3]. Despite the production of near-net shaped objects, the LPBF experiences some shortcomings concerning the surface roughness of as-fabricated parts, which relates to several physical phenomena: i.e., conduction heat transfer, balling effects, and tension gradient on the melt surface; and, process variables: i.e., morphology of powders, spot size, power, speed, and trajectory of the scanning beam [11]

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Conclusion