International Conference on Advances in Design and Manufacturing (ICAD&M'14)
238
Effect of Spindle Speed, Feed Rate & Axial Load on Friction Stir Welding of Polyethylene Plates V. Jaiganesh, D. Jaya kumar and E. Gopinath Abstract--- Thermoplastics are used widely in day-to-day applications so it is important to join plastics effectively. Thermoplastic materials are easily joined by friction stir welding. Joining of thermoplastics in friction stir welding which is based on frictional heat generated through contact between a rotating tool and the work piece. The determination of welding parameters plays an important role in weld strength. In friction stir welding of thermoplastics, traditional tools form a slit on the backside of welded specimen which leads to root defect causes poor tensile strength. Due to the high transparency of this polymer, it was possible to analyze easily the morphological changes induced by the welding process on it. In this investigation the welding parameters studied were the tool rotation speed which varied between 800 and 1200 (rpm), transverse speed which varied between 40 and 200 (mm/min), axial force ranging from 1 to 5 (KN). An attempt was made to join the High Density Poly Ethylene (HDPE) plate of 5 mm thickness with different tool profiles (square, cylindrical and triangular threaded pin profile. In this investigation the quality of the joint was evaluated by means of tensile strength and micro structural analysis.
and shoulder where the frictional heat and deformation heat is produced. Friction stir welding (FSW) is widely used for several application were it is important to keep the original characteristics of the material. FSW helps in producing complicated 3D seems weld. FSW is considered as the most significant metal joining in a decade which is a green technology due to its energy efficiencies, eco-friendly and versatile. The main goal is to join the polymeric materials (polyethylene-PE) applicability and factors influencing the strength of the weld. Welding process was performed by changing the pin profile, rotational speed of the pin, feed rate.
Keywords--- FSW, Morphology, Polymer, Polyethylene, Tensile Strength
F
I.
INTRODUCTION
RICTION stir welding is a solid state material joining process developed and patented in 1991 by The Welding Institute (TWI). Initially aluminium alloys are joined using FSW but in the current scenario polymers, magnesium, titanium, steel, metal matrix composites of different combinations. The main advantages of FSW are very ease of automation, less distortion, superior mechanical properties and minimum residual stresses. Despite initially the qualities observed for certain applications such as super plastic formation which results good mechanical properties. In this process there is no solidification and fusion of the material takes place during welding. The characteristics of the parent material are preserved to be same compared to other traditional welding process. A non consumable rotating tool with designed pin and shoulder is inserted in between the plates to be welded. The tool consists of two main parts: pin
V. Jaiganesh, Professor, Department of Mechanical Engineering, S.A. Engineering College, Chennai, India. E-mail:
[email protected] D. Jaya kumar, Student, Department of Mechanical Engineering, S.A. Engineering College, Chennai, India. E-mail:
[email protected] E. Gopinath, Student, Department of Mechanical Engineering, S.A. Engineering College, Chennai, India. E-mail:
[email protected]
Fig.1: Photographic View of Friction Stir Welding Machine II.
EXPERIMENTAL WORK
Materials and Equipment Polyethylene is a thermoplastic polymer consisting of very long and strong hydrocarbons which is used for wide range of applications in field of automobiles, aerospace, making containers, electrical insulations, kitchen ware and packages in the form of thin films and sheets. Polyethylene is weathered and unusually rebellious to many chemical solvents, bases and acid. It is one type of versatile polymer available with applications, both as a plastic and as a fiber. Polyethylene provides better results in terms of ductility, fracture toughness, strength and fatigue compared to other thermoplastic materials. Plate of polyethylene - PE composites with 20 wt % and 150 X 50 X 5 mm size were fabricated in the butt-weld configuration shown in figure-2. The experiment was conducted on HURCO VM20 vertical machining machine of X, Y, Z axis and a spindle speed ranging from 45 – 1500 rpm with a feed range of 0.25 to 500 mm/min. The travel length was made along these directions were 1016 X 508 X 508 mm respectively shown in figure-1.
ISBN 978-93-84743-12-3 © 2014 Bonfring
International Conference on Advances in Design and Manufacturing (ICAD&M'14)
This machine is equipped with a spindle motor power of 5 kW which provides a 3 tonne mechanical linear axial force in the X direction. The polyethylene plates were fixed firmly in their positions on the fixture of FSW machine.
239
A cylindrical pin tool profile was used in this experiment where the tool is of 15mm diameter shoulder and a pin diameter of 5 X 5 mm and 4.8 mm height which is made up of HSS (high speed steels) and the tool is subjected to heat treatment with the hardness of 65 HRC.
Fig.2: Polyethylene Plates Before Welding Table 1: Mechanical Properties of Polyethylene Plates Properties of polyethylene
Fig.3: Photographic View of Tool Pin Profiles
Polyethylene
High density
Yield strength MPa Density g/cm3 Ultimate strength MPa
24-37 0.95 55
Melting point oC
115-135
Tool Materials and Selection In FSW the material of the tool is the most important parameter for determining the quality of welding. Selection of the tool material greatly depends on the material of the work piece to be welded Non consumable rotating tool fabricated from HSS(high speed steel) grade of M42 is taken as the tool material for joining polyethylene. The main reason for choosing HSS as a tool material among the miscellaneous variety of tool materials like High carbon high chromium, tool steel, carbide, carbon boron nitride is because of its ease of availability, low cost, more strength and long life-time. Tool Geometry Different types of tool profiles are used in this experiment to weld the polyethylene sheets. The tool profiles are cylindrical, cylindrical tapered and cylindrical grooved. All tool pin profiles are fabricated in CNC Turning centre and optical profile grinding machine. A cylindrical tapered tool with the tool dimensions of 15mm diameter shoulder and a pin diameter of 5 X 3 mm and 4.8 mm height which is made up of HSS(high speed steels) and the tool is subjected to heat treatment with the hardness of 65 HRC. The cylindrical grooved tool has 15mm diameter shoulder, pin diameter of 5 X 2.5 mm and 4.6mm height which is made up of HSS (high speed steels) and the tool is subjected to heat treatment with the hardness of 65 HRC.
Table-2: Tool Geometry Pin profile
Length of the pin 4.8 4.8
Cylindrical Cylindrical tapered Cylindrical grooved
Diameter of the pin
4.6
Inner
Outer
5 5
5 3
5
2.5
Welding Parameters and Fabrication: There are certain parameters of FSW affecting the characteristics of welding. The welding parameters that influence the welding characteristics are rotational speed (RA), feed rate (FR), and tilt angle (TA). Table 3: FSW Process Parameters Input parameters Axial force Feed rate Tool rotational speed Tilt angle
Unit KN mm/min RPM Degree
Range 1-4 6-12 900-1500 0-10
Table 4: Experimental Data of Various Pin Profiles Speed of the tool (RPM) 1000 1250 1500 1000 1250 1500 1000 1250 1500
ISBN 978-93-84743-12-3 © 2014 Bonfring
Feed rate (mm/min)
Tilt angle (degrees)
6 10 12 6 10 12 6 10 12
0 1 1 0 1 1 0 1 1
Tool profile
Cylindrical
Cylindrical tapered Cylindrical grooved
International Conference on Advances in Design and Manufacturing (ICAD&M'14)
240
Fig.4: Photographic View of Polyethylene Plates Fixed in the Fixture of Friction Stir Welding It is proven that these three levels of process parameters bonds, etc,. More number of investigations is made about the were considered after conducting trial welding. These impact of HSS tool on polyethylene plates continuously and it parameters are required for obtaining acceptable welds. The gave the quality weld while using HSS tool of geometry cross section and slope of tool probe are very essential for having 30 mm shoulder diameter to a length of 35 mm and mixing-shearing effects. Direction of molten material was cylindrical taper pin with a diameter of 4mm and 5mm controlled by spindle speed. FSW was successfully carried out diameter. on a number of polyethylene flat plates at different spindle speeds, feed rate, tilt angle by applying 2-3 KN of axial force. III.
RESULTS AND DISCUSSIONS
Optimising the process parameter is the very difficult task, various trials were conducted to bring the optimized spindle speed, feed rate using different pin profiles. Among these three pin profiles cylindrical tapered tool profile gave the better welding compared to other pin profiles. Cylindrical tapered was selected because it gave quality weld for various spindle speed and feed rate. In the first stage of the experimentation the spindle speed of the tool is taken as 1000RPM, feed rate of 6 mm/min and tilt angle is 0o where lot of chips formed with discontinuous blow holes, which indicates the joining weld is not good. In the second stage of experimentation with the same spindle speed of 1000 RPM and increasing the feed rate to 10mm per/mm, tilt angle 1 o better joining was observed compared to previous stage. Thus the feed rate of 10mm/min is made constant Maintaining the feed rate and tilt angle as the same but increasing the spindle speed to 1250 RPM the weld defects in the welded area was reduced so the joining in the polyethylene plates were good. Further the spindle speed was increased to 1500 RPM the polyethylene plates are over melted and the plastics in the molten form run away from welding area and so the joining was not proper. Hence a conclusion was made that at 1250 RPM with a feed rate of10mm/min, tilt angle 1 o was the optimized process parameters for polyethylene plates.
Fig.5: Welded Polyethylene Plates in Butt Weld Configuration through FSW by Cylindrical Tapered Tool Pin Profile Tensile test specimen The better welded polyethylene plates were cut and reduced to the required thickness using water jet cutting (WJM). After cutting the polyethylene in WJM the extra profiles that are stuck on the welded areas are filed to obtain the flat surfaces. The tensile test was carried out on the welded polyethylene plates are to find the ultimate tensile stress and yield strength. The tensile test was carried on the welded polyethylene plates using a universal testing machining. The machine has a testing load range of 5 ton electromechanical controlled. The evaluation of various tensile properties like ultimate strength, yield strength and elongation were carried out on the welded polyethylene plates.
Weldments obtained using HSS (high speed steel) tool The plates which are welded using HSS tools are found to be free from welding defects such as cracks, pin holes, kissing
ISBN 978-93-84743-12-3 © 2014 Bonfring
International Conference on Advances in Design and Manufacturing (ICAD&M'14)
a
241
b
Fig.6 a) Specimens that are Cut Through WJM for Tensile Test in Universal Tensile Testing Machine b) Polypropylene Plates After the Tensile Test in Universal Tensile Testing Machine The tensile strength obtained by the joints was 19MPa Likewise the yield strength obtained by the joints was which is 34.54% of the parent material tensile strength 13MPa which is 54.16% yield strength of the parent material (55MPa). (24MPa) and the elongation being 14%.
a
b
Fig.7 a) Load-Displacement Curve Generated After the Tensile Test of the Polyethylene Plates Through Cylindrical Tapered Tool b) Stress-Strain Curve Generated After the Tensile Test of the Polyethylene Plates Through Cylindrical Tapered Tool Macro test on the polyethylene plates after tensile test Defects during welding Macro test were conducted on the welded specimen to find Blow holes were formed during the weld when the where the breakage occurs exactly. rotational speed is less than the 1000 RPM.
Fig.8: Macroscopic View of Polyethylene Plates After Tensile Test This concluded that the strength was lower on the adjacent side of the weld while using the cylindrical tapered tool. Thus the breakage was initiated from the point on the adjacent side of the weld.
Fig.9: Welded Polyethylene Plates Consisting Defects The strength on the blow holes area is very low. The formation of the chips is more and discontinuous at lower spindle speed where as at higher spindle speed run away of polyethylene from the welding area due to overheat.
ISBN 978-93-84743-12-3 © 2014 Bonfring
International Conference on Advances in Design and Manufacturing (ICAD&M'14)
IV.
CONCLUSION
The welding of polyethylene plates through Friction stir welding (FSW) at optimal conditions.
The cylindrical tapered tool produced effective weld and superior mechanical properties compared to Straight cylindrical and cylindrical grooved under optimized FSW process parameters. The tensile strength was 34.54% of the parent material tensile strength by using cylindrical tapered pin profile. Moreover, the yield strength was 54.16% of the parent material tensile strength and the elongation was 14%. It has been found that the cylindrical tapered tool is suitable for joining polyethylene plates with a thickness of 5mm through FSW was proven experimentally. Cylindrical tapered tool provides lesser welding defects and higher mechanical properties at optimized spindle speed of 1250 RPM with 10mm/min feed rate and 1o tilt angle compared to other pin profiles. REFERENCES
[1]
[2]
[3]
[4]
[5] [6]
[7]
[8]
[9] [10] [11]
[12]
[13] [14]
242
[15] YahyaBozkurt. “The optimization of friction stirs welding process parameters to achieve maximum tensile strength in polyethylene sheets.” Materials and Design 35, 2012, 440–445 [16] Thomas WM, Nicholas ED, Needham JC, Murch MG, Templesmith P, Dawes CJ. “Friction Stir Butt Welding,” GB Patent No. 9125978.8; 1991 Dr. Jaiganesh V was born in Tiruvallur, Tamilnadu, India, in 1977. He received his B.E. degree in Production Engineering from the Madras University, Chennai, India, in 1999, and successfully completed M.Tech. degrees with First Class in Industrial Engineering from the National Institute of Technology (NIT) Trichy, India, in 2003 and obtained his Ph.D. in Mechanical Engineering from Anna University, Chennai in 2009. He completed his master of Business Administration degree from IGNOU, New Delhi in the year 2005 with First Class. At Present he is working as a Professor in the Department of Mechanical Engineering, S A Engineering College, Chennai. His research interest includes Modern Welding Process, Sustainable technology, Manufacturing Energy Management. He is a Life Member of the Indian Society for Technical Education (ISTE), Institution of Engineers (IEI) and Charted Engineer (C-Engg) from IEI. He was awarded Mahatma Gold Medal Award by GEPRA, New Delhi. He has published 6 international journal papers and published more than 20 papers in International and National conferences. Presently he is guiding 6 Ph.D scholars from different universities under his guidance. He obtained a research grant of Rs.13 Lakhs from AICTE for his research activity on Eco-Friendly High Strength Friction Stir Welding under Research Promotion Scheme.Email:
[email protected]
Arici, A., Selale, S., Effects of Tool Tilt Angle on Tensile Strength and Fracture Locations of Friction Stir Welding of Polyethylene, Science and Technology of Welding and Joining, 12, 2007, pag. 536-539 Sevvel, P., Jaiganesh, V., Improving the mechanical properties of friction stir welded AZ31B magnesium alloy flat plates through axial force investigation, Applied Mechanics and Materials Vol. 591 (2014) pp 11-14. K. Panmeerselvam, Lenin K, Investigation on effect of tool forces and Joint defects durig FSW of Polypropylene plate, Procedia Engineering 38 (2012) 3927-3940. Jaiganesh, V., Sevvel, P., Effect of Process Parameters during Friction Stir Welding Of Al 6063 Alloy, Advanced Materials Research Vols. 984-985 (2014) pp 604-607. Arici, A., Seno, M., Friction Stir spot Welding of Polypropylene, Journal of Reinforced Plastics and Composites,27, page.2001-2004. Sevvel, P., Jaiganesh, V., Experimental Investigation on the impact of the Tool Material & geometry in joining of Al 63400 Alloy using Friction Stir Welding Process, Applied Mechanics and Materials Vols. 592-594 (2014) pp 312-315. Erica Anna Squeo, Giuseppe Bruno, Alessandro Guglielmotti, FabrizioQuadrini., Friction Stir Welding Of Polyethylene Sheets, The Annals Of “Dunărea De Jos” University Of Galaţi Fascicle V, Technologies In Machine Building, Issn 1221- 4566, 2009 A., Selale, S., Effects of Tool Tilt Angle on Tensile Strength and Fracture Locations of Fracture Stir Welding of Polyethylene, Science and Technology of Welding and Joining, 12, 2007, pag. 536-539 Kiss Z, Czigany T (2007). Applicability of friction stir welding in polymeric materials. PeriodicaPolytechnica. 51(1): 15-18 Ma, Z.Y., Friction Stir Processing Technology: a Review Metallurgical and Materials Transactions A, 39A, 2008, pag. 642-658 Mohamed-Ali Rezgui, Ali-ChedliTrabelsi, MahfoudhAyadi& Khaled Hamrouni, Optimization of Friction Stir Welding Process of High Density Polyethylene International Journal of Production and Quality Engineering Vol. 2, No. 1, January- June 2011, pp. 55-61 K. Panneerselvam, S. Aravindan And A. Noorul-Haq, “Joining Of Plastics By Frictional Vibration”, International Symposium Of Research Students On Materials Science and Engineering, Chennai, India, December 2004, 20-22. R.S. Mishra, Z.Y. Ma, “Friction Stir Welding and Processing”, Materials Science and Engineering R., 50 (2005), 1-78. AdilShaikh, K.D. Bhatt, Alok B. Chaudhary , Effect Of Friction Stir Welding Process Parameters On Polymer Weld,International Journal For Technological Research In Engineering Volume 1, Issue 9, May-2014 ISSN: 2347 – 4718
ISBN 978-93-84743-12-3 © 2014 Bonfring
Jaya kumar D was born in Thiruvannamalai, Tamilnadu, India, in 1994.He pursues his B.E. degree in S.A. Engineering College, Chennai, Tamilnadu, India. E-mail:
[email protected]
Gopinath E was born in Vellore, Tamilnadu, India, in 1993. He pursues his B.E. degree in S.A. Engineering College, Chennai, Tamilnadu, India. He was going to publish his paper in a reputed international journal. [1] Optimizations of process parameter on friction stir welding of high density polypropylene plate, procedia engineering, elsevier publication.E-mail:
[email protected]
