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1 Science Ats & Méties (SAM) is n open ccess epositoy tht collects the wok of Ats et Méties PisTech eseches nd mkes it feely vilble ove the web whee possible. This is n utho-deposited vesion published in: Hndle ID:. To cite this vesion : Snd ZIMMER, Luent LANGLOIS, Julien LAYE, Jen-Clude GOUSSAIN, Ptick MARTIN, Régis BIGOT - Influence of pocessing pmetes on the tool nd wokpiece mechnicl intection duing Fiction Sti Welding - 29 Any coespondence concening this sevice should be sent to the epositoy Administto : chiveouvete@ensm.eu

2 Influence of pocessing pmetes on the tool nd wokpiece mechnicl intection duing Fiction Sti Welding S. Zimme, L. Lnglois, J. Lye 2, J-C. Goussin 2, P. Mtin, R. Bigot Ats et Meties PisTech, LCFC, 4 ue Augustin Fesnel, 77 METZ, Fnce 2 Institut de Soudue, FSW Cente, 2-4 ue Pilte de Rozie, 742 GOIN, Fnce ABSTRACT: Duing Fiction Sti Welding pocess, FSW, tool / wokpiece mechnicl intection is geneted leding to foces nd toques pplied on the tool. These foces nd toques e tnsmitted to the welding equipment impcting its technicl equiements. This ppe pesents foces nd toques nlysis ccoding to the pocessing pmetes on the welding t constnt speed stge. The nlysis ws pefomed on the whole welding pocess windows, by vying one pocess pmete fte the othe. The gol of this wok is to detemine if nd how the foces nd toque could be educed by woking on the pocessing pmetes. So, with lowe foces nd toque pplied on the tool, the use of stndd nd flexible welding equipment, llowing the welding of complex geometies, could be enbled. KEYWORDS: Fiction Sti Welding, Welding stge, Pocessing Pmetes, Pocess foces nd toque INTRODUCTION Fiction Sti Welding (FSW) is n innovtive welding pocess commonly known s being solid stte welding pocess []. This pticulity gives it the vilbility to weld lmost ll types of luminium lloys, even the one clssified s non-weldble by fusion welding due to hot ccking nd poo solidifiction micostuctue in the fusion zone [2]. To pefom FSW, non-consumble otting tool, mde up of shoulde nd pin, is inseted into the intefce of two wokpieces igidly clmped. Once the shoulde in contct with the sufce s wokpieces, constnt down foce is pplied on the tool nd is moved long the joint line, bounding the wokpieces togethe. The pocessing pmetes e chosen in ode to ensue the enegy input nd the tool kinemtics in ode to chieve defect-less weld. In consequence, duing the whole welding pocess foces nd toques e geneted in the thee diections, impcting the welding equipment equiements. Ou esech field is the industilistion of the fiction sti welding, in ode to povide tools to industils to qulify FSW welding equipment o to define equiements fo buying new equipements. 2 NOMENCLATURE F z [kn] Axil foce F x [kn] Foce in the tvel diection F y [kn] Foce pependicul to F x C z [Nm] Spindle Toque v [mm/min] Tvel speed N [t/min] Tool ottionl fequency E n [J/mm] Nominl enegy, defined s been the totl welding powe divided by the tvel speed. 3 DEFINING THE CARACTERISTIC PARAMETERS The fist step is to nlyse the tool / wokpiece mechnicl intection on the whole welding pocess. The objective is to detemine the pocess nd mchine chcteistic pmetes. The Figue pesents the common foces nd spindle toque evolution thoughout Fiction Sti Welding. Foces [kn] Plunge Spindel Toque Dwell Time Foce in the tvel diection, F x Temps Time [sec] [s] Acceletion Welding t constnt speed Axil Foce, F z Weld speed Schemtiztion Foce pependicul to the tvel diection, F y Tvel Foce Ltel Foce Axil foce Spindle Toque Deceletion Toque [Nm] Retcting of the tool Figue : Visuliztion of the foces nd toque pplied on the tool duing the FSW pocess Zimme nd l [3] conclude tht the foces nd toque geneted duing the plunging nd the welding t constnt tvel speed wee chcteistic fo sttic qulifiction of FSW mens of poduction. Theefoe, these two welding stges should be investigted in ode to nlyze the influence of the pocessing pmetes on the tool / wokpiece mechnicl intections, Figue 2. The mechnicl intections e tnsmitted by the tool S. ZIMMER -Ats et Méties PisTech Metz 4, ue Augustin Fesnel- 77 Metz cedex 3 33() snd.zimme@metz.ensm.f

3 to the welding equipment equiing cetin stiffness, foces nd toques cpcities. Theefoe, one wy to enble the use of flexible nd stndd welding equipment, llowing the FSW of complex geometies, is to wok on the pocessing pmetes in ode to educe the lod pplied on the welding equipment while ensuing good weld qulity. Genelly this type of equipment is identified s being limited in foce cpbility nd lck of stiffness []. Tool geomety Geomety welded Mteils welded Pocessing pmetes Input Pmetes FSW Mechnicl intections between the tool nd wokpiece mteil Pocess Weld qulity Nominl Enegy [J/mm] Foces [kn] Chcteistics Toques [Nm] pmetes to Powe [W] qulify FSW Etc. mchine Output Pmetes Figue 2: Reltion between the input nd the output pmetes This ppe focuses on the tool kinemtics nd mechnicl intection poduced duing the welding t constnt speed, the stge leding to the joint genetion. The Figue 2 pesents the tool kinemtics nd the mechnicl intection pplied on the tool duing the welding stge t constnt tvel speed. F tool ωx Tvel diection, v tvel [mm/min] z O Anvil F z C z y F tool Tool Welded Mteil Figue 2: Tool / Wokpiece mechnicl intection The foce pplied by the tool on the wokpiece is given by the eqution (). F = F x + F y + F z tool/ wokpiece tool tool z () The eqution (2) gives the momentum pplied by the tool, on point O, on the wokpiece mteil. In the following study, the toque components L x nd L y pesented in the eqution (2) is not tken into considetion nd e ssumed to be equl to zeo. T tool / wokpiece, O = L x + L x y y + C z z (2) So, this ppe will focus on the study of the influence of the welding pocessing pmetes (N, v, F z ) on the foces nd toques geneted without nlyzing the plunging stge. 4 EXPERIMENTAL PROCEDURE In ode to nlyse the influence of the pocessing pmetes on the tool nd wokpiece mechnicl intection duing the welding stge, ech pocessing pmetes wee modified one fte nothe. The pocessing pmetes evolved so tht the whole pocess window ws coveed. Theefoe, ll the tests led to sound welds, i.e. without intenl o extenl defects. The Figue 3 pesents the pocessing pmetes nd the nlysed output pmetes. The tilt ngle ws set up t 2. nd emins fixed fo ll the tests. N [t/min] v tvel [mm/min] F z [kn] i [ ] Input Pmetes FSW Welding t constnt ottionl nd tvel speeds Pocess Pmetes tnsmitted to the FSW welding mchine Weld qulity Nominl Enegy [J/mm] F x [kn] C z [Nm] F y [kn] Powe [W] Output Pmetes Figue 3: Reltionship between the studied output pmetes nd the input pmetes In ode to stt the welding stge in the sme initil themo-mechnicl conditions, the plunging nd dwell pocessing pmetes wee set up identiclly fo ech welding tests. The welded length ws 3mm. All the tests wee pefomed in 6mm thick, 6 luminium lloy plte. The selected tool is conventionl tool, mde of steel, with concve shoulde nd cone-shpe theded pin. All the expeiments wee pefomed t the Institut de Soudue, on MTS-ISTIR- Fiction Sti Welde, fully instumented mchine. RESULTS The expeimentl esults will be decomposed into two cse studies, nlysing the output pmetes F x, F y, C z nd E n esponses when: - the xil foce is evolving nd N nd v emins constnt, - N nd v e evolving, one fte nothe, nd F z emins t the sme vlue All the nlysis hs been pefomed on the stedy stte welding potion, i.e. when C z, N nd v emin constnt.. Evolution of the output pmetes when F z is evolving The detemined pocess windows, of the selected mteil, enbles to evolve the xil foce F z fom to 2.kN fo N nd v emining constnt. The Figue 4 pesents the spindle toque evolution ove the xil foce nge. Supisingly, s the xil foce knows % vition, the spindle toque evolves only of 8%. So, n xil foce incese does not imply n incese of the tool ottion esistnce. As the xil foce pplied is incesing it could be supposed tht the equied toque would become moe impotnt. This smll toque evolution could be

4 explined by tngentil stess pplied on the tool limited by the mteil flow yield stess. Theefoe, even if the noml foce inceses, s the mteil she stess is eched, the toque does not know significnt incese. This type of mteil behviou ws lso identified in hot foging. The totl powe needed to pefom the welding opetion is defined s being C z ω [3], becuse the powe elted to the tool tvel motion is negligible ginst the powe developed fo the tool ottion. Theefoe, s v constnt, the nominl enegy lso evolves fom 8%, Figue 4. The evolutions of F x nd F y e not significnt s F z vy but thei vlues lwys emined unde 2% of F z. Spindle Toque [Nm] Spindle Toque, Cz Nominl enegy, En Fz [kn] Nominl Enegy [J/mm] E n = Powe v Cz π N = 3 v π f ( N ) N 3 v (3) Theefoe, when F z nd N e set up s constnt nd v is vying, the eqution (3) numeto emins constnt becuse C z is not sensitive to vition of v. So, in this cse, the nominl enegy is function of (/v ). The stong influence of v cn be seen on the Figue 6. On the othe hnd, when F z nd v e set up s constnt nd N is vying, the nominl enegy will be influenced by the vition of N nd the vition of C z. So, the nominl enegy is pinciplly function of N nd v. Spindle Toque [Nm] Cz=f(V); N=cst Cz=f(N); V=cst Figue 4: Spindle toque Cz nd Nominl enegy E n evolution s the xil foce pocess nge.2 Evolution of the output pmetes when N nd v e evolving On the othe hnd, when N o v e vying, one fte nothe, ove the whole pocess windows, the toque nd the foces F x nd F y does know some evolution. The Figue pesents the spindle toque evolution when N nd v e vying. It cn be noted tht, when the spindle fequency inceses, the toque does know significnt decese. A tool spindle fequency incese involves highe mteil stin te ound the tool but lso fictionl het input incese. Both e leding to het input incese, descibed by the nominl enegy Figue 6, nd consequently mteil tempetue incese geneting mteil viscosity decese fcilitting the tool ottion. On the othe side, the spindle toque doesn t seem to be sensitive to the tvel speed incese, becuse n incese of 7% only involves 6% toque incese. So it cn be conclude tht the mteil flow ound the tool, elted to the tool tvel motion, isn t significnt in the mteil het input. Theefoe, it cn be noted tht the toque is pinciplly function of the spindle fequency. Theefoe, it cn be noted tht the toque is pinciplly function of the spindle fequency. With the pevious conclusions, the nominl enegy cn be defined s being: Figue : Evolution of the spindle toque ccoding to R Nominl Enegy [J/mm] En = f(v); N=cst En = f(n);v =cst Figue 6: Nominl Enegy, E n, evolution ccoding to R On the othe side, F x nd F y doesn t know line evolutions s N nd v e vying independently, Figue 7 nd Figue 8. This implies tht thei mximl o miniml vlues e not locted t pocess windows extemity. It is inteesting to study the tnsvesl foce esponses s the tvel speed deceses, fo N emining constnt, geneting nominl enegy incese. In fist time, s R 2, the tnsvese foce F y decese due to n incese of het input geneting she stess decese ound the pin. Then, even if the tvel speed continues to decese, the tnsvese foce hs tendency to gow. This could be explined by tion (N/v ) involving highe mteil sheing speed nd theefoe n incese of the she stess esponsible of F y incese

5 Howeve, it cn be noted on Figue 8 tht the tvel foce, F x, is vey sensitive to vition of v. F x is decesing with decese of v nd consequently n incese of E n, t N constnt. This tvel foce decese could be explined by n incese of the plsticised zone in font of the pin, due to moe het input, fcilitting the tool tvel long the wokpiece intefce [4]. The esults showed tht F x nd F y mximl vlues could ech 3% of the pmeteized vlue F z. Foce [kn] E n = 49J/mm.7.6. Fy=f(V); N=cst Fy=f(N); V=cst E n = 4J/mm Figue 7: Evolution of the tnsvese foce, F y, ccoding to R, fo N nd v vying ech fte one othe Foce [kn] E n = 49 J/mm Fx=f(V); N=cst Fx=f(N); V=cst E n = 4 J/mm Figue 8: Evolution of tvel foce, F x, ccoding to R, fo N nd v vying ech fte one othe 6 CONCLUSION AND FUTURE WORK The pesented expeimentl esults wee obtined by the fiction sti welding pocess window explotion. Theefoe, the numeicl esults e depending on the used tool geomety, the welded mteil nd thickness. The evolution of F x, F y nd C z, ccoding to the pocessing pmetes, pesented bove e genel mteil behviou. These tendencies e pobbly the esults of the combintion of the stin te incese nd of the viscosity decese due to the mteil tempetue incese. Theefoe, they should be pplied fo othe tool geometies nd welded mteil. The esults showed tht the Fiction Sti Welding esulting foces nd toques, geneted duing welding,. e be influenced by the input pmetes, N, v nd F z. Theefoe it is not bsud to wok on these pocessing pmetes in ode to educe the lod pplied on the welding equipment. The nlysis showed tht C z does not be sensitive to vition of v nd F z. Fo the tool nd mteil chosen, fo N nd v set up s constnt, F z knows wide pocess nge. This chcteistic is inteesting when the ppliction should be pefomed on stndd flexible mens of poduction, limited in foce cpcity, like n industil obot. On the othe side, C z nd F x e vey sensitive to vition of N nd v. In ode to minimize thei vlue, high ottionl speed nd low tvel speed should be tken. This suggests tht compomise will pobbly to be mde between weld qulity nd lod tnsmitted to the welding equipment. As mentioned befoe, two welding stges e chcteistic fo the sttic qulifiction of FSW mens of poduction. The welding stge ws one of it. Theefoe, the second one, the plunging, should be investigted in the sme mnne. Then, the plunging nd welding pocessing pmetes, llowing the use of mens of poduction with limited foces cpcities, cn be chosen. Thus, the whole welding pocess will be defined fo n industil ppliction. So this study shows tht fo ppliction point of view it is necessy to contol the intection between mnufctuing pocess nd mchine nd in ode to choice the mnufctuing pmetes. ACKNOWLEDGEMENT The uthos would like to thnks the Region Loine nd the Moselle deptment to finncilly suppot this esech poject nd Dniel Stin fo its technicl suppot. REFERENCES [] W.M. Thoms, E.D. Nichols, J.C. Needhm, M.G. Much, P. Templemith, C.J. Dwes, Ptent Appliction, No (Decembe 99). [2] R.S Mish, Z.Y. M, Fiction Sti Welding nd pocessing, Mteils Sciences nd Engineeing R (2) I-78 [3] S. Zimme, L. Lnglois, J. Lye, J.-C. Goussin, P. Mtin, R. Bigot, Methodology fo qulifying Fiction Sti Welding equipment, Poceedings of the 7 th Intentionl Symposium on Fiction Sti Welding 28 [4] S. Sheiki, Hestellung und Bewetung de Umfombkeit von eibühgeschweissten Tiloed Blnks us Aluminiumlegieungen, Ph. D Wok, Univesity of Duisbug-Essen 2 [] M. Soon, FSW of high-stength luminium lloys using nd Industil obot system: fesibility study, 7 th Intentionl Symposium on Fiction Sti Welding 28