Manufacturing Technology Today

M. Sasidhar ¹, A. B. Srinivasarao ¹, A. M. K. Prasad ², K. Mohanrao ³

Affiliations
1 K. L. College of Engg., Vaddeswaram, Guntur Dist, AP, IN
2 College of Engg., Osmania University, Hyderabad, AP, IN
3 C. R. Reddy College of Engg., Eluru, W. G. Dist., AP, IN

Abstract

Friction Stir Welding, a relatively new welding process, was developed in 1991 at The Welding Institute near Cambridge, England. In this process parts are mated together, rigidly fixtured, and joined in solidstate by forcing a rotating tool into the joint, and traversing that tool along the joint. This process creates weldments with properties comparable to the base metal, and in most cases superior to traditional fusion welding techniques. This is a solid state joining process, which is currently being developed for difficult to weld high strength aluminum alloys (e.g. the 2xxx and 7xxx series). This new technique is being successfully applied to the aerospace, automobile, and shipbuilding industries, and is attracting more and more research interest. In FSW the temperature distribution is very important parameter, in order to see that the materials being welded are not melted and the joining of the materials is taking place successfully. A good understanding of the heat transfer process in the workpiece can be helpful in predicting the thermal cycles in the welding workpiece, and the hardness in the weld zone, subsequently, can be helpful in evaluating the weld quality. An attempt is made to find the temperature distribution in FSW fleet through experimentation.

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M. Sasidhar ¹, A. M. K. Prasad ², A. B. Srinivasa Rao ¹

Affiliations
1 Dept, of Indl. & Production Engg., K L College of Engg., Vaddeswaram, IN
2 Dept. of Mechanical Engg., College of Engg., Osmania University, Hyderabad, IN

Abstract

Friction Stir Welding (FSW) was invented and patented by The Welding Institute (TWI) in 1991 [1]. The FSW process involves forcing a rotating tool consisting of a protruding pin and larger shoulder into a material, and traversing the tool along the work piece joint. The rotating tool generates frictional heat which causes the material to plastically flow around the tool. The shoulder usually contains a concavity which allows material to flow and produces a forging pressure on the trailing end of the weld. A lot of work is being canned out to measure the most important and substantial longitudinal forces thus generated, being a critical component for proper tool design. In the present experiment an attempt was made to invent a new technique to measure the longitudinal force distribution on a friction stir weld pin tool.

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M. Sasidhar ¹, A. M. K. Prasad ², K. Jayanendra Babu ¹

Affiliations
1 Dept. of Industrial and Production Engg., K L College of Engg., Vaddeswaram, IN
2 Dept. of Mechanical Engg., College of Engg., Osmania University, Hyderabad, IN

Abstract

In late 1991, The Welding Institute (TWI), a British research and technology organization, invented and patented a welding process named Friction Stir Welding (FSW). Since its introduction, FSW development has progressed rapidly and is currently being used in a number of aerospace and industrial applications. Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, stir together, and forge a bond between two metal alloys. A welding tool moves along the area to be joined while rotating at a high speed. The action between the tool and the aluminum creates frictional heat, which softens the aluminum but does not melt it. The plasticized material is then, in essence, consolidated to create one piece of metal where there were originally two. In this paper, a FSW process with varying pin geometries (cylindrical and conical) and advancing speeds is numerically modeled, and a thermo-mechanically coupled, rigid-viscoplastic, fully 3D FEM analysis able to predict the process variables as well as the temperature distribution. The obtained results allow finding optimal tool geometry for improving nugget integrity of aluminum alloys.

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