Metal additive manufacturing is a rapidly expanding area owing to its capacity to fabricate parts of intricate geometries with customized features for a wide range of applications. However, these parts generally exhibit inadequate and poor surface quality in the as-built configuration. The surface imperfections and defects ranging from staircase effect due to the layer by layer nature of the deposition techniques, partially fused feedstock material, balling effects, spatters, or inadequate fusion lead to a notably irregular surface morphology. This high surface roughness can significantly deteriorate the performance of the additive manufactured parts imposing a substantial limit on their prospective applications; for instance, fatigue performance, wear and scratch resistance, dimensional accuracy, and aesthetical aspects can be highly affected by these surface defects. A great effort has been lately dedicated to developing post-treatments for improving the surface quality of additively manufactured metallic parts. In this paper, various treatments applied to as-built samples fabricated using different additive manufacturing technologies are introduced and discussed. The advances in this area are highlighted, and the results obtained from different categories of post-treatments are compared and reviewed. Challenges and opportunities to gain more control on the surface roughness of additively manufactured metallic parts through the application of these post-treatments are addressed.

Surface post-treatments for metal additive manufacturing: Progress, challenges, and opportunities

Wire and arc additive manufacturing : Opportunities and challenges to control the quality and accuracy of manufactured parts

Additive manufacturing (AM) technology, in other words “layered manufacturing” or “3D printer technology” has been developing rapidly in recent years. Unlike the traditional manufacturing method (TM), the working principle of AM technology is to create layer-based production by deposition the layers on top of each other. Owing to its advantages such as material saving, lower cost, the ability to produce parts without the need for molds and the design flexibility in complex shaped parts, it has brought a breath of fresh air to the areas where it is used primarily medical, aerospace and automotive. However, the parts produced by AM method have dimensional limitations. According to recent studies, in order to eliminate this problem, metal materials produced with AM can be combined with commonly used by different welding methods so that large parts can be obtained. In this study, these welding methods are explained and recent researches are examined. AM technology and methods are introduced. The usage areas of the method are described. In addition, the welding parameters and the effects of this new method on the mechanical properties and microstructures are investigated.

Additive manufacturing method and different welding applications

This paper starts from the early developments and working principles of the additive manufacturing of polymers, continues with a glimpse on the extension to metals with identification and characterization of the two most widespread technologies, and ends with an overview of the recent developments in hybrid metal additive manufacturing. Earlier classifications of hybrid manufacturing with roots on the utilization of primarily processed raw materials in the form of ingots, sheets, rods, tubes, profiles, powders and pellets are revisited in the light of the emergence of a new type of hybridization resulting from the combination of additive manufacturing with traditional manufacturing processes. Special emphasis is given to the combination of additive manufacturing with forming processes with the two-fold objective of (i) increasing the applicability domain of metal additive manufacturing and overcoming its limitations related to low productivity, metallurgical defects, rough surface quality and lack of dimensional precision, and (ii) adding flexibility and fostering new applications of traditional forming processes.

Hybrid metal additive manufacturing: A state–of–the-art review

An insight into additive manufacturing of fiber reinforced polymer composite

Surface quality and forming characteristics of thin-wall aluminium alloy parts manufactured by laser assisted MIG arc additive manufacturing

The invention provides a laser-dipulse MIG (metal-inert gas welding) composite heat source arc AM (additive manufacturing) method for an aluminum alloy and workpieces. According to the method, low-power pulse laser and dipulse MIG arc are adopted as composite heat sources, an aluminum alloy welding wire is molten to perform surfacing on a substrate according to a designated path, surfacing layersare overlapped layer by layer, and a required aluminum alloy structural member is formed. According to the laser-dipulse MIG composite heat source arc AM method for the aluminum alloy and the workpieces, the low-power pulse laser and the dipulse MIG arc are composited, characteristics of two technologies of laser welding and arc welding are achieved, after the laser and the dipulse MIG are composited, pulse laser with high-peak power acts on a molten pool periodically, so that liquid metal in the molten pool is in a circulation of backward flowing-forward refilling, and equivalently, a strongstirring effect is realized; by means of the impact effect of dipulse waveform, the pore defect in a formed sample can be effectively reduced and even eliminated.

Chengshuai Sun

Papers

Surface quality and forming characteristics of thin-wall aluminium alloy parts manufactured by laser assisted MIG arc additive manufacturing

Laser-dipulse MIG (metal-inert gas welding) composite heat source arc AM (additive manufacturing) method for aluminum alloy and workpieces