Laser Polishing of Directed Energy Deposition Metal Parts: A Review

Abstract

Additive manufacturing (AM) is a reliable technique for constructing highly complex metallic parts. Direct energy deposition (DED) is one of the most common technologies used for AM-printed metal alloys. However, issues such as weak binding, poor accuracy, and rough surfaces still affect the final products. These limitations in the metal-feed DED process indicate that post-processing techniques are required to achieve high quality in terms of both mechanical properties and surface finish. Conventional contact-based post-processing methods have several drawbacks, including difficulties in accessing complex shapes, environmental impact, high time consumption and cost, and health risks for operators. To address these problems and improve surface quality, a laser polishing process has been proposed. By melting or ablating the material with a laser, the laser-polishing process enables the smoothing of the initial topography. It should be noted that there are currently no reviews focusing specifically on laser polishing as a surface treatment technology for the DED process. Therefore, this review presents a unique examination of the mechanisms and primary user-set parameters for both continuous wave (CW) and pulsed laser polishing. The objective is to demonstrate the capabilities of each process and the benefits of using them for the surfaces of DED metal parts. Additionally, existing knowledge and technology gaps are identified, and future research directions are discussed.

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