Understanding the Impact of Cooling Systems on Bulk Additive Friction Stir Deposition of Aluminum

This work presents an investigation of two cooling systems used in additive friction stir depositions (AFSD) and the related effect on process temperature, feed material, and life of processing equipment. A new AFSD cooling system, Mazak MegaStir Liquid-cooled Toolholder (LCTH), was integrated onto MELD Manufacturing AFSD machines using both continuous and discrete material feeding systems. The LCTH is compared to the original MELD cooling system to understand how process temperatures are controlled by the cooling systems, how feed material interacts with the process under different cooling conditions, and how well the cooling systems protect the equipment. It is shown that spindle revolution rate impacts the temperature experienced by the bearings more greatly than the utilization of cooling. The attempt of three large volume depositions demonstrates the necessity of a cooling system utilization for AFSD. Additionally, four configurations of tool and cooling system are analyzed to understand parameters that affect depositions temperature and the thermal effect on feed material. Configurations with short working face to cooling distances show ~40 K cooler deposition temperatures and configurations with the new LCTH deposited ~9 K cooler than those deposited with the original MELD cooling system. Microhardness analysis on feed material revealed the varying efficacy of each cooling configuration’s ability to enable bulk deposition. The influence of feed system on process temperatures is also presented with a comparison of discrete and continuous feed system depositions.