Generally, molds are fabricated by the machining of massive billets of tool steels, such as AISI4140 or H13, but it has drawbacks, such as a large material loss and long-delivery time. The Wire-Arc Additive Manufacturing (WAAM) process could be an alternative fabrication method. It has the advantages of less material loss, short-delivery time, and the chance to make a reinforced mold using dissimilar materials. 5 Cr – 4 Mo steel wire has high potential to produce molds via the WAAM process. This is a commercial tool steel solid wire initially designed for the repair and modification of tools and molds that has superior hot wear resistance and toughness. However, no study has examined the WAAM of tool steels, even though it has high potential and advantages. Shielding gas has a significant effect on the performance of the WAAM process, which is based on gas metal arc welding (GMAW). Argon (an inert gas) and carbon dioxide (a reactive gas) are generally used for the GMAW of steel alloys, and they are frequently used as mixed gases at various ratios. Shielding gases have a significant influence on the arc stability, weld quality, and formation of weld defects. Therefore, using a proper shielding gas for the material and process is important to sound WAAM performance. This paper discusses the effect of the shielding gas on the additive manufacturability of tool steel, as a first step for the WAAM of die casting molds. The experiments were conducted with two different shielding gases, M21 (Ar + 18% CO2) and C1 (100% CO2). The use of C1 showed neither surface contamination nor internal defects, and resulted in a larger amount of deposition than the M21.
Owing to global trends, automation with the fourth industrial revolution, and environmentally friendly policies owing to certified emission reduction, wire arc additive manufacturing (WAAM) is attracting attention in various industrial fields. In addition, the demands of non-ferrous metals such as aluminum and magnesium alloys are attracting attention from industries that require lightweight, large, and complex metallic parts that can be fabricated through WAAM. In this study, additive manufacturing (AM), WAAM, and current issues on the WAAM of non-ferrous metals particularly aluminum and magnesium alloys are discussed.
Die casting molds for aluminum are fabricated using machining billets of tool steels, such as Cr-Mo tool steel. However, this approach has several limitations, including significant material loss and a long lead time. Wire arc additive manufacturing (WAAM) is an alternative fabrication method that yields low material loss and has a short lead time. However, WAAM involves the repetitive stacking of layers based on designed tool paths using CAD/CAM. Thus, the predictability and uniformability of each layer are the most important factors. The interpass distance is an important parameter in a given process; however, studies on the interpass distance of the WAAM process are limited. In this study, it was determined that the interpass distance significantly influences the arc stability owing to the arc interference induced by the variation in distance from the prior deposited pass; more arc interference was observed as the interpass distance decreased. This phenomenon was validated via analysis using a high-speed camera and the variation in the amount of spatter. Furthermore, it was observed that the interpass distance influences the dimensional precision and uniformability. The interpass distance influences the arc interference unless it is greater than 100%. Thus, it is important to determine a point of balance based on the arc stability, dimension predictability, and uniformability of each layer.
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