The Development of a Friction Stir Extrusion Machine for Producing Multiscale Extruded Cylinders and Hollow Tubes

Abstract

Abstract Friction stir processing is being used to improve characteristics of advanced manufactured process by improving the strength and ductility of material, joining, surface characteristics, and alloying. In addition, friction stir processing may be used as a first step for recycling metallic waste. The authors are interested in the friction stir processing because they see that friction stir extrusion may be used for producing unique components that could be useful for the development of fuel cells, micromanufacturing, heat exchangers, biomedical applications, and MEMS. The goal of the current project is to develop a custom built friction stir machine in order to investigate multi-scale friction stir extrusion processes. The machine will be used to characterize various friction stir extrusion processes such as forward and backwards extrusion to produce solid cylinders and tubes with outside diameters up to 37-mm down to 3-mm and for tubes with internal diameters down to 2-mm. In addition, various materials will be evaluated for friction stir extrusion processes and the process parameters will be used. The machine described is being implemented in 3 phases. The first phase was the building of the basic machine and perform open-loop tests. The second phase was the implementation of process monitoring and begin to implement closed-loop control. The third phase of building the friction stir machine is to fully implement closed-loop control and begin charactering specific processes. This paper describes the current state of the project (Phase 2). A force transducer, thermocouple, and a displacement transducer are used to monitor the process parameters. A PLC is used to record the process parameters as well as control the 10HP 3-phase 240v ac electric motor that powers the rotating probe. Open-loop tests where the extrusion process was performed manually by the equipment operator were performed where the operators attempted to control forces during the tests and to perform component and system integration tests. A-1100-o aluminum solid billets 12.7mm in diameter were used to produce tubes (OD: 12.7-mm, ID: 6.35-mm). Observations, temperatures, and forces were recorded and are presented. Because this machine was a proof-of-concept machine that is being converted to a production machine, observations made will be used to improve the machine for Phase 3.