Dimension Precision and Uniformability Depending on the Interpass Distance Variation of Automated-Wire Arc Additive Manufacturing using 5 Cr-4 Mo Tool Steel Alloy

Abstract

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.