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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 6 2 8 Fig. 6 — 150-ton mechanical LFW system.

SUMMARY

LFW is a solid-state process capa- ble of joining noncircular parts by oscil- lating one part under load to create fric- tional heating. Advancements in LFW machine design have led to a new me- chanical oscillation system, enabling new applications due to a decrease in equipment cost, reduction of the ma- chine footprint, and an increase in the technology’s processing capabilities. Potential applications vary from exist- ing aerospace components and dissim- ilar materials joining to heavy duty ap- plications such as rail joining. The LFW process is able to make aluminum-to-steel joints with a match- ing strength of aluminum alloy and also produce full-section rail steel welds. LFW is an emerging technology with uses that are still being defined. ~AM&P For more information: Michael Eff is a project development engineer, EWI, 1250 Arthur E. Adams Dr., Columbus, OH 43221, 614.688.5212, meff@ewi.org, www.ewi.org. References 1. S. Shapiro, Hydraulics at the Core of the Largest Ever Welder, Machine Design, machinedesign.com/article/ hydraulics-at-the-core-of-largest-ever- linear-friction-welding-machine-0316, 2010. 2. I. Bhamji, et al., Solid State Joining of Metals by Linear Friction Welding: A Literature Review, Materials Science & Technology, Vol. 27(1), p 2-12, 2011. 3. J. Gould and S. Johnson, Advances in Translational Friction Welding through Next Generation Mechanical Oscilla- tors, TWI-EWI Aerospace Conference, 2012. 4. L. Ceschini, et al., A Study on Similar and Dissimilar Linear Friction Welds of 2024 Al Alloy and 2124Al/SiCP Com- posite, 6th International Conference on Processing and Manufacturing of Advanced Materials – THERMEC 2009, p 461-466, 2010. 5. G. Jerry, W. Johnson, and S. John- son, Application of Translational Fric- tion Welding Rail Assembly and Repair, AREMA 2012.

Fig. 7 — Full-section rail joined by LFW.

toughness, and overall poor joint qual- ity. Both optical and scanning electron microscopy identified any intermetallic compound present at the joint interface as shown in Fig. 5. Working with the Federal Rail- road Administration, EWI and APCI co- developed a 150-ton mechanical LFW machine (Fig. 6) capable of joining full section railroad rail (8400 mm 2 ) [5] . This machine can apply up to 1335 kN of axial load and maintain part

oscillation under this load. Currently, rail is joined using thermite or flash butt welding, which results in exces- sive rail shortening. LFW reduces rail length loss from welding while main- taining current joint performance. This length loss reduction decreases the tension placed on the rail due to elongation. By reducing the stress placed on the joint, rail service life is greatly increased. A photo of a welded rail is shown in Fig. 7.