Issue 43

F. Berto et alii, Frattura ed Integrità Strutturale, 43 (2018) 1-32; DOI: 10.3221/IGF-ESIS.43.01 24 Figure 29: Experimental setup of Al-Al HYB configuration: HYB spindle extruder (2), steel fixture (3), and aluminum plates to be welded (6). Some of the final results are shown in Fig. 30, and confirm a good joint appearance. Still some work needs to be carried out, since some crack-like defects are evident, which demands that both equipment and control software be upgraded. The potential of this technology is very high and it should be considered to expand the capabilities of the HYB machine. The idea could be raising the possibilities by simply changing the spindle and its mount. By doing so, the machine would become multipurpose considering additive manufacturing and hybrid welding applications. The main advantages given by this new way of joining should be increasing quality and efficiency of overall welding properties, where less amount of energy is wasted than that in other processes, by decreasing temperatures as well. Critical is understanding how materials react in this process. Figure 30: Optical macrograph of the joint cross section. The HYB machine has been modified by mounting a different spindle extruder. During the welding procedure, the aluminum and steel butt plates are fixed leaving a little gap between them. The butt surface of the steel plate has been previously beveled and fixed leaving 2 mm of space from the center of the welding, while the aluminum plate presents a vertical surface, Fig. 31. This spindle extruder has a specific shape, capable of squeezing plasticized aluminum in the gap between the plates while moving the material close to it. In this way, the tool operates also a strain work on the aluminum side. This new version of the spindle extruder has been called PinPoint spindle.