| Abstract Scope |
While friction stir welding (FSW) in a CNC machine is gaining popularity as combining the processes becomes more practical, the effects of thermal input must still be considered. Heat generated from the welding process may negatively affect the machine and components. Machine accuracy, part-life, and warping of components may all suffer some amount of degradation due to elevated levels of thermal input inherent to the welding process. Components such as the spindle and drives may also be negatively affected due to a lack of heat management at the tool. While underwater FSW has previously been researched as a means of continuous cooling, this process is not feasible in a CNC machine. One proposed solution to this issue is to utilize the existing machining coolant, flooded over the tool during welding, to reduce temperature levels at the weld and additionally reducing the amount of heat transferred back into the tool that may damage or warp machine components. Flooding coolant, forced air cooling, and no cooling, as is the case with conventional FSW, were compared. Feed rates varied to study their effect on each cooling method. In this study, 6.35 mm samples of AA6061-T6 were welded in a butt joint configuration and the feed rates were 100, 200, and 300 mm/min. It was observed that the most ideal welding qualities were found by flooding coolant at a feed rate of 100 mm/min. When coolant was implemented during welding, 76% tensile strength was achieved along with increased hardness in the stir zone. Although narrowing of the weld zone occurred along with voids at the surface in samples FSW with coolant. This was due to lower levels of heat for the duration of welding which impeded plastic material flow more so than when no cooling was utilized. |