No abstract

Three customized stirring tool pin profiles have been designed which are (1) straight cylinder, (2) triangle shape, and (3) tapered shape to be used by reconfigured milling machine (Cheng Yin – CY-GH 260) to perform friction stir welding process. Shoulder geometry is constant for all tools (20 mm having 8 deg concave and length of the pin from shoulder is 2.7 mm). Then, all the tools were fabricated and tested by joining two similar plates of Al 6061 and Al 7075. The tools are made of H13 steel (chromium-molybdenum). Welding parameter used are 1270 RPM for rotating speed and 218 mm/min for welding speed. The samples produced were evaluated based on physical appearance of weldment, tensile strength value, surface roughness value, and physical tool wear. From the result, all the designed and fabricated tool pin profiles were able to perform FSW successfully using reconfigured milling machine. Tapered tool produced the highest tensile strength with 134.95 MPa. However, straight cylinder tool produced smoothest surface roughness with 1.850 μm which provide better surface finish. Weldability of Al 6061 is better compared to Al 7075.

Friction stir welding (FSW) is a solid-state joining process that has many advantages including the ability to join high strength alloy as well as dissimilar metals which are hard to be joined by conventional fusion techniques. This welding process involves the penetration of rotating tool which consist of shoulder and prolonged by a pin into a metal plate. The process is followed by advancing speed to weld the metal plate. However, it requires a specialized machine to perform the joining process. A new FSW system including its tools may be costly and thus becomes the main barrier to the development of this FSW process in industry. One of the possible solutions is by adapting the current conventional milling machine with additional rotating and feeding principles to suit the FSW process requirement. In this work, suitable tools, jigs and fixtures for FSW process using conventional milling machine were designed. The design of the tool, jigs and fixtures were fabricated and tested by joining two similar plates of A6061 aluminium alloys. The investigation shows promising results with defect-free welds, good strength and smooth surface finish without gap creation between the welded plates.