![]() ![]() Softened material is displaced and expelled from the joint during processing in the form of flash. To complete the cycle, the amplitude of oscillation is decayed to zero bringing the moving component into perfect alignment under an axial forge loading which consolidates the joint. The surface and subsurface of both components are heated and the material is transformed into a softened plastic state. a blade) against the surface of a stationary component (i.e. The solid phase process, illustrated in Fig.2, generates frictional heat by axially pressing, under a predetermined load, the surface of a laterally reciprocating component (i.e. Illustration of the linear friction welding process World-wide industrial acceptance of the economic benefits and the high weld quality produced when using rotary friction welding to join round section metallic components led to the development of LFW at TWI Ltd. filed a patent giving equipment and process details for making linear friction welds between steel components. When the development and uptake of conventional rotary friction welding was at its height, the potential application of LFW was described as 'very doubtful' by Vill'. Reciprocating motion for friction welding, and then linear friction welding were proposed respectively in 1929 by the German Richter and in 1959 by the Russian Vill'. As titanium alloy blisks are in production today, the welding of these alloys is focused on in this document. This review paper introduces the linear friction welding (LFW) process with respect to its application for blisk manufacture and outlines the key characteristics which make it viable as a manufacturing route, along with the properties of the joints produced between aero engine materials. ![]() Illustration showing the reduction in material and part count between a conventional mechanically attached blade-disk assembly and a linear friction welded blisk A further benefit of the blisk design is, that it is lighter compared to the conventional component.įig.1. By eliminating the mechanical joint and introducing a fully welded blisk or IBR (Integrated Bladed Rotor) the fretting fatigue problem in the attachment region is removed. Conventional fir-tree or dove-tailed disk to blade attachments, as shown in Fig.1, are often the life limiting factor of a rotating stage in a compressor due to fretting fatigue damage at the mechanical joint. The reliability, lifetime and temperature capability of today's state-of-the-art designs are inadequate for future VHBR-engines. New and innovative rotor designs as envisaged for Very High Bypass Ratio (VHBR) engine concepts, are leading to substantially higher rotating speeds in the low pressure compressor and higher end temperatures for each stage of the engine. The feasibility of improved aero engines with regard to lower fuel consumption, reduced exhaust gas and noise emission, life cycle costs and enhanced reliability depends on the achievements of research and development activities concerning the processes and materials applied.Īdvanced compressor and turbine designs are critical to achieve these goals. The gas turbine industry is bound to continue improving its technical capabilities in terms of achieving higher efficiencies and safety standards and of complying with future environmental legislation. This paper reviews the application of LFW for titanium alloy blisk manufacture. Aero engine and other gas turbine manufacturers have and continue to focus considerable attention and investment on this technology. Applicable to joining titanium alloys in the compressor stage and to directionally solidified or single crystal nickel based alloys in the turbine stage, the process is considered a rapid, low cost fabrication route for titanium blisks. Linear friction welding (LFW) is an established niche technology applied by world leading leading gas turbine aero engine manufacturers to fabricate bladed disk (blisk) assemblies. Paper presented at 1st International Conference on Innovation and Integration in Aerospace Sciences, 4-5 August 2005, Queen's University Belfast, Northern Ireland, UK. National Structural Integrity Research Centre.Structural Integrity Research Foundation. ![]()
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