DESIGN AND DEVELOPMENT OF A FIXTURE FOR FRICTION STIR WELDING

Transcription

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 9, September 2017, pp , Article ID: IJMET_08_09_013 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed DESIGN AND DEVELOPMENT OF A FIXTURE FOR FRICTION STIR WELDING G. C. Jadhav PhD Scholar, Department of Mechanical Engineering, Government College of Engineering Sant Gadge Baba Amravati University, Amravati, Maharashtra State, India Dr. R. S. Dalu Professor and Head, Mechanical Engineering, Government College of Engineering Sant Gadge Baba Amravati University, Amravati, Maharashtra state, India ABSTRACT Friction Stir Welding being a solid-state process is free from defects generally occurs in fusion welding process. FSW of aluminium alloy has been done on universal milling machine. The high cost and non-availability of friction stir welding machine motivated this research to design and make a new fixture. Many forces appear during the friction stir welding process. They are torque, transverse, axial and lateral forces. Due to presence of these forces the main challenge is to withstand all these forces and this is one aim to fabricate the fixture. For FSW process there is design, development and tested the new economical fixture for universal milling machine. Keyword head: Friction stir welding, fixture, clamps, drilling, milling. Cite this Article: G. C. Jadhav and Dr. R. S. Dalu, Design and Development of a Fixture for Friction Stir Welding, International Journal of Mechanical Engineering and Technology 8(9), 2017, pp INTRODUCTION Friction Stir Welding (FSW) was invented at The Welding Institute (TWI) of UK in 1991 as a solid-state joining technique, and it was initially applied to aluminium alloys [1]. Many various engineering industries will give importance for aluminum and aluminum based alloys. Friction stir welding was initially applied to aluminium alloys [3, 4, 5]. A non-consumable rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of sheets or plates to be joined and traversed along the line of joint. The parts have to be suitably clamped rigidly on a backing bar to prevent the abutting joint faces from being forced apart. The length of the pin is slightly less than the required weld depth (7). The plunging is stopped when the tool shoulder touches the surface of the job. The tool shoulder should be in intimate contact with the work surface. The function of tool is heating of work-piece, and movement of material to produce the joint. The heating is accomplished by friction between the tool and the editor@iaeme.com

2 G. C. Jadhav and Dr. R. S. Dalu work-piece and plastic deformation of work-piece (8). The localized heating softens the material around the pin and combination of tool rotation and translation leads to movement of material from the front of the pin to the back of the pin. Because of various geometrical features of the tool, the material movement around the pin can be quite complex [9]. Here a substantial forging force is applied by the tool to consolidate the plasticized metal behind the tool. The welding of the material is facilitated by severe plastic deformation in the solid state involving dynamic recrystalisation of the base material. As the tool is moved along the seam the desired joint is created. The schematic view of the operation is shown in Figure1 [10]. Figure 1 Friction Stir Welding Friction stir welding is considered to be the most significant development in metal joining in decades and in addition, is a green technology due to its energy efficiency, environmental friendliness, and versatility [3, 4, 12]. The benefits include the ability to join materials which are difficult to fusion weld, such as aluminum alloys. The process is suitable for automation and adaptable for robot use. The welding process does not need filler wires and weld pool shielding gas. No porosity, splatter, grinding, brushing or pickling required in mass production Oxide removal immediately before welding is unnecessary. The process is clean and does not produce any major safety hazards, such as welding fume or radiation [6]. 1.1 Difficulties in FSW A good design of fixture can lead to dissipating heat away from the workpiece, and hence improving the weld quality and performance [13]. He developed a fixture that accommodates both backing plate and metal plate to be welded [14]. There is development of a clamping system and an instrumented setup for a vertical milling machine for friction stir welding (FSW) operations and measuring the process forces. Taking into account the gap formation (i.e., lateral movement) and transverse movement of the workpiece, a new type of adjustable fixture was designed to hold the workpiece being welded [15]. The fixture required to carry out the FSW process efficiently in a conventional milling machine is not well discussed in published literatures. Friction stir welding has been used for purpose-designed equipment or modified existing machine tool technology. The future is bright because it will open many more cost- effective opportunities for FSW in many industries such as railway, marine, transportation, refrigeration and electrical [7] editor@iaeme.com

3 Design and Development of a Fixture for Friction Stir Welding Difficulties faced in FSW process from the above research paper are: - 1. Fixture arrangement will be required. 2. It creates a visible hole in welding plates. 3. High initial or set up cost. 4. It is less flexible compared to arc welding process. 5. It cannot make filler joint. 2. PROPOSED RESEARCH PLAN The aim of this paper was to develop a set up for FSW and fabricate defect free weld. Any machines to achieve specific tasks have been considered very important in the industry. The high cost of specialized machines makes them less accessibility and usability. Here the modifications in machines are necessary meet specific tasks with low cost and simple way. Due to high cost and non-availability of FSW machine motivated to design and make a new fixture. Also many forces appear during the friction stir welding process. They are torque, transverse, axial and lateral forces. Due to presence of these forces during the friction stir welding process, the main challenge was to withstand all these forces and this was one of the aims to developing the fixture. 2.1 About machine and work piece Universal milling machine has been used for experimentation. Vertical attachment has used to hold the FSW tool. Two work piece of rectangular shape have been used to joint by FSW process. One end made a drill of 6 mm on the surface of the workpiece so that shoulder of the tool rest on the workpiece easily. It is easy to support the axial force on workpiece. Figure 2 and 3 shows the milling machine and the workpiece use for FSW purpose. About Machine: Specification: Name of company: Batliboi Ltd, Surat. Name of machine: Universal milling machine BFU-5 Spindle Table Size Transverses: Longitudinal Cross Spindle Speed Spindle Feed Spindle Power ISO x mm 405 mm rpm mm/min 5.5 kw Figure 2 Milling Machine About Workpiece: AA 6061-T6 aluminum alloy of thickness 6.3mm, chemical composition and mechanical properties are given in table 1 and 2 respectively. Table 1 Chemical composition in %wt. Mg Si Fe Cu Cr Mn Zn Ti Al Balance editor@iaeme.com

4 G. C. Jadhav and Dr. R. S. Dalu Yield strength inmpa Table 2 Mechanical properties. Ultimate strength in MPa Elangation % Hardness in HV Figure 3 Workpiece 3. DESIGN AND DEVELOPMENT OF FIXTURE The main purpose of a fixture for friction stir welding is to hold the work pieces in position during welding. However, there has limited published information that details the fixture design requirements. In each of joint designs and fixture arrangements, it is necessary to give enough area for welding tool shoulder path, provide enough force to prevent motion of the workpiece, provide adequate heat sink to dissipate the heat of welding. A workpiece, just like any free solid body, has twelve degrees of freedom such as six rectilinear displacements and six angular displacements along the mutually orthogonal coordinate axes. The general principle of location is most commonly used. During a setup, it is necessary to restrict certain degrees of freedom so as to locate and orient the active surfaces with respect to the FSW tool. Since supporting or restricting surfaces may vary from the true geometrical shape, especially on rough-machined surfaces or cast blanks, it is desirable that the workpiece be located with respect to the point supports. Here the first three points the large area of base plate is taken and for two points the fixed side plate does this work. Here instead of three pins plane flat base is used. By using this five directions of movement are restricted. To restrict the three movement of the part around Z axis and the direction Y axis, here instead of two pin fixed flat supporting plate is used. The remaining four degree of freedom has been restricted by a C- clamp. A fixture consists of a set of locator and clamps. Locators are used to determine the place and orientation of a workpiece, whereas clamps exert clamping forces so that the work piece is press firmly against locator. Clamping has been appropriately planned at the stage of machining fixture design. The design is simple, cost effective and will be fastened on any milling machine bed. The fixture is made up of various parts. To fabricate the system from one piece is too difficult taking in account the high cost and complexity. During the initial stages, many pieces were fabricated separately then one of them was joined together to form as a single component. CATIA P3 V5 R17 software package is used to prepare the part drawings and elements to the engineering drawing to design the fixture. This reduces the time. The various parts are described briefly in Figure 4. A. Work piece: AA6061-T6 of thickness 6.34 mm. Size: 100 x 82x 6 mm Operation: Cutting, filing, drilling and finishing. Machine used: Hydraulic power hacksaw and drilling editor@iaeme.com

5 Design and Development of a Fixture for Friction Stir Welding B. Base plate: Because of the increased tool forces, fixtures are built stronger and heavier. The material used for this is mild steel having dimensions 216x168x20 mm and weight of base plate 5.63 kg. Base plate has 13 drills with threading of 10 mm. C. Fixed plate: Left side of base plate having dimension 216 x 25 x 10 mm is directly joined by arc welding to the base plate as shown in assembly of fixture. D. Side supporting plate: This plate is movable and having dimensions 204 x 62 x 10 mm. This plate has 100 mm groove having depth 5 mm and breath is 6 mm. Also have three 10 mm drill holes. T-bolts are used to locate the workpiece position. Also position of the locator should space as far apart from the actual welding position. Fool proofing is that it ensures that workpiece fit into the tool only in its correct position. E. C-Clamps: Two clamp plates made of mild steel flat with dimensions 164 x 32 x20 mm are used to prevent the axial movement and vibration of the work pieces. Each plate is provided with three holes of 10 mm. Here clamp is designed by the shape and size of the workpiece, the fixture being used, and the work is to be done. Two hole of 6 mm and depth 20 mm used for connecting hinges. So easily unloading of workpiece done. F. Backing plate: This plate is made up of stainless steel having dimensions 160 x 100 x 3 mm. The use of this plate prevents the damage of fixture during welding also reduce the heat transfer from welding to base plate. Figure 4 In CATIA 3D view of the various components of the system 3.1 Developing the fixture Considering above versatile features, the design of fixture was prepared using the CATIA. Assembly as shown in Figure 5 has been prepared by measuring the dimensions of the bed of universal milling machine on which the FSW has to be performed. Mild steel has been used for manufacturing the parts due to its high strength and toughness which is required to withstand unbalanced force and pressure during FSW operation editor@iaeme.com

6 G. C. Jadhav and Dr. R. S. Dalu Movable supporting plate C-clamps Hinges Base plate Fixed Side plate Figure 5 Draft of fixture design 4. FABRICATION AND TESTING OF THE FIXTURE After finalizing the drawing details and product design features, all main parts were fabricated at small dimensional tolerance. They were fabricated individually before assembled together by using bolts and fasteners. The final product is shown in the Fig.5. Different parts of fixtures are fabricated in our workshop. The parts list of fixture as shown below Table 1. Table 1 Parts used in fixture Part List A. Workpiece Aluminium 2 B. Base plate M.S. 1 C. Movable supporting plate M.S. 1 D Fixed side plate M.S. 1 E. C-Clamp M.S. 2 F. Backing plate S.S. 1 G. Nut and bolt C-30 9 H. Hinges S.S. 2 The fabricated fixture of universal milling machine was tested for its stability and reliability, by operating it at various parameters during the FSW process. Figure 6 shows the experiment setup where the fixture was fastened on the milling machine table. Nonconsumable tool made of high chromium high carbon steel with varying speed, feed, axial pressure, tilt angle, shoulder diameter; 4.2 mm pin length and 6 mm pin diameter was selected for this operation. The fixture was successfully mounted on the milling machine table. Few samples were successfully joined by friction stir welding process. During the operation no vibration was observed and also there was no distortion in the samples editor@iaeme.com

7 Design and Development of a Fixture for Friction Stir Welding Final fixture with sample Testing of fixture Testing Samples of AA6061T-6 Figure 6 Final product of FSW fixture with testing samples 4. CONCLUSION Proposed fixture has been designed, developed and tested successfully on universal milling machine (BFU-5).It possesses the strength to sustain downward load acted by the spindle force against its structure The advantage of utilizing the existing milling machine by adopting the application of fixture for FSW process can be justified economically, where it is more affordable compared to purchasing an actual FSW machine. REFERENCES [1] Thomas WM, Nicholas ED, Needham JC, Murch MG, Temple-Smith P, Dawes CJ, Friction stir butt welding, International Patent Application No. PCT/GB92/02203; 1991 [2] C.J. Dawes and W.M. Thomas, Friction Stir Process Welds Aluminum Alloys, Weld. J., 1996, 75, pp [3] Thomas W. M. and Nicholas E. D., Friction stir welding for the transportation industries, Materials & Design, 18,1997, pp [4] Thomas W. M., Friction stir welding recent developments, Mater Sci. Forum 2003; : editor@iaeme.com

8 G. C. Jadhav and Dr. R. S. Dalu [5] M. Ecomoto, Friction stir Welding: Research and industrial applications, Welding International (2003), 17(3), pp [6] Mishra R. S., Ma Z. Y., Friction stir welding and processing, Mater Sci Eng: Rep 50 (1 2); 2005, pp [7] Peel M, Steuwer A, Preuss M, Withers P J, Microstructure, mechanical properties and residual stresses as a function of welding speed in aluminium AA5083 friction stir welds, Acta Mater 51: ,2003, doi: /s (03) [8] G. Elatharasan,V.S. Senthil Kumar, An experimental analysis and optimization of process parameter on friction stir welding of AA6061-T6 aluminium alloy using, Procedia Engineering, 64,2013, pp [9] Mustafa Boz and Adem Kurt, The Influence of Stirrer Geometry on Bonding and Mechanical Properties in friction stir welding process, Journal of Materials and Design, 25, 2004, pp [10] Singh R. K. R., Sharma C., Dwivedi D. K., Mehta N. K., Kumar P., The microstructure and mechanical properties of friction stir welded Al Zn Mg alloy in as welded and heat treated conditions, Materials and Design, 32, 2011, pp [11] Edward G. Hoffman, Jig and Fixture Design, (Singapore, Fifth Edition by Thomson Asia Pvt. Ltd., Second Reprint, 2005) pp [12] M. Snigdha, C. Satya Sandeep, G. Swathi, Suresh. R, P. Hanuma and Praveen. B, Design of Fixture for the Manufacturing of Compressor Rotor Blade in Aircraft Engine, 8(7), 2017, pp , 8(7), [13] P. Yogesh, C. Arun, R. Arunkumar, S. Muruganantham and P. Abinesh, Elimination of Rejection in Injector Manufacturing Process by using Hydraulic Fixture. International Journal of Mechanical Engineering and Technology, 8(3), 2017, pp [14] Daniela Lohwasser, Zhan W. Chen, Friction stir welding: From basics to applications (Aukland University of Technology, New Zealand Wood head Publishing Ltd. and CRC Press LLC, 2010). [15] Fratini L, Micari F, Buffa G, Ruisi VF., A new fixture for FSW processes of titanium alloys. CIRP Annals - Manufacturing Technology. 2010; 59: [16] P. K. Baghel, Design and development of fixture for friction stir welding, Innovative Systems Design and Engineering, 12, 2012, pp [17] B. Parida, S. D. Vishwakarma, and S. Pal., Design and development of fixture and force measuring system for friction stir welding process using strain gauges, Journal of Mechanical Science and Technology, 29(2), pp , editor@iaeme.com