Simulating the effect of gating design and pouring temperature on LM4 casting quality

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1 Simulating the effect f gating design and puring temperature n LM4 casting quality Ganesh P. Brikar MIT, Research Center, Savitribai Phule Pune University Pune, Maharashtra-38, India ganesh.brikar@mitpune.edu.in Sandip T. Chavan MIT, Research Center, Savitribai Phule Pune University Pune-38, Maharashtra, India Mahesh L. Kulkarni JSPM Narhe Technical campus Savitribai Phule Pune University Pune-38, Maharashtra, India ABSTRACT Tday sand casting is used enrmusly due t its inherent advantage f n size and shape limitatin and lw cst. Hwever the majr issue f defect and yield need t be addressed further. The apprpriate cntrl ver prcess parameters and design f gating system can reslve the stated prblem t greater extent. The defects like distrtin, prsity and cld shut /mis-run are very much dependent n melt temperature, slidificatin rate and design f gating system. In present case attempts have been made t cntrl the prcess by studying the effect f puring temperature and gating system design. A cmmercial sftware AutCAST-X1 is used fr the purpse. It shws that t btain unifrm cling and directinal slidificatin twards feeder, use sprue psitin at center and side feeder shuld be used as in present case f cylindrical shaped hllw stepped casting f LM4 ally. As gating rati and melt puring temperature is increased, shrinkage prsity and cld-shut defects are minimized t greater extent. The best gating rati designed is 1:3:3 and puring temperature f 682 C fr LM4 ally. Keywrds: Gating rati, Melt puring temperature, Feeder design, Directin slidificatin, Liquid fractin. 1. INTRODUCTION Cnventinal methd f casting is based n experience and thumb rules. It cnsists f a number f steps frm pattern making t fettling and inspectin n shp flr. It is time cnsuming and the prcess itself cnsists f lt f parameters. Althugh lt a f research wrk is dne n sand casting t get a sund casting free frm defects is still a challenge. Virtual casting prcess using simulating sftware helps in speeding casting prcess design. It prvides defect free casting t custmer frm the very first time and in less lead time. 1 Ravi has wrked n feeding analysis and ptimizatin wrk using simulatin.feedability analysis is based n lcatin f ht spts, feed paths and temperature gradient 2 in slidificatin simulatin. Khandelwal et.al.investigated the flwability f ZA 8 and LM6 ally thrugh thin sectins t understand the manufacturability limits fr a particular cmbinatin f gemetric, material and prcess parameters.the effect f shape f flw path, length and thickness cmbinatin f casting gemetry fr particular allys and muld material need t be studied further t understand prcess capabilities. 3 Savithri, et.al.perfrmed wrk n btaining simulatin results f temperature distributin and slidificatin time at different lcatins in muld fr single cavity and multi- 4 cavity layut with cube shaped casting.omer, et.al. wrked n factrs affecting micrprsity n A36 Alally casting by using Taguchi methd. The effect f muld filling flw, filtratin, slidificatin time, melt hydrgen level, and melt with Strntium (Sr) additin parameters 5 were investigated. Vsniaks, et.al. the studied evlutin f slidificatin prcess f slid cylinder f pure aluminium A199.5, since it affects micrstructural prperties and frmatin f defects. 6 Murat, et.al. in their study investigated effects f change f casting dimensins n casting sundness fr sand cast A36 Al ally. Initially simulatin runs n different scaled mdels was perfrmed using simulatin sftware Slid CAST t bserve sundness in frm f shrinkage prsity. 54 TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA

2 7 Santhi, et.al. had studied t predict prsity in US A356 and US 413 aluminium allys fr cylindrical shape casting using FDM sftware. In this different gemetry effect need t explred further. It is bserved thrugh referred literature ( 2-7) that, effect f gating system design and melt temperature n casting quality, defects, micrstructure and yield are nt yet defined as standard prcedure fr casting design. In the present wrk, the effect f gating system design and melt temperature n casting is studied. The casting design, metal flw and thermal analysis is carried ut using AutCAST-X1 simulatinsftware t predict directin slidificatin, htspt-shrinkage prsity and cld shut. 2. DESIGN OF GATING SYSTEM AND MOULD LAYOUT The selected casting cmpnent is cylindrical stepped hllw shape as shwn belw in Fig.1 Design f gating system cnsist f design f pattern, design f sprue with sprue well, layut f runner and gate, design f feeder, muld design, t estimate slidificatin time and yield. Casting prcess used is sand casting and casting material used is LM4 ally (Al-Si12) f which cmpsitin is prvided in Table1. Fig.1Cmpnent gemetry CENTER SPRUE AND SIDE SPRUE: i. Psitin f sprue at center f cmpnent and tw symmetrical runners with gate gives flw and slidificatin simulatin as shwn in Fig.2 prvides mre equal distributed cling f cmpnent(temp. f C and 56.7 C). Table1. Cmpsitin f ally LM4 Al Cu Mg Mn Si Zn Pattern is designed with cnsideratin f shrinkage allwance, machining allwance and draft allwance fr external surface and internal bre/cavity. Frm the mdel f pattern mass prperties are btained. Design f sprue, gating system and 8,9,1,11 feeder gives Wt. f casting =368 gm., Puring time= 1.51 sec. 2 Chke area = 155 mm,sprue height = 42 mm Sprue well diameter =24 mm, Gating rati= 1:3:3 - Use f parting gating, with tw runners and gates, - Feeder diameter = 3 mm, qty. 1 n. SPRUE POSITION AND TOP/SIDE FEEDER LAYOUT Effect f sprue psitin at center f cmpnent and at side f cmpnent is studied by flw and slidificatin simulatin using AutCAST-X1 with FLOW+ Mdule fr htspt psitins and directinal slidificatin. Fig. 2 Slidificatin f casting with sprue psitin at center and at side. TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA 55

3 ii. Psitin f sprue at side f cmpnent and ne runner cnnecting t bdy f cmpnent results in the flw and slidificatin simulatin as shwn in Fig.2, the cnsiderable temperature difference in the cmpnent is bserved which is (temp. f C and C). TOP AND SIDE FEEDER: Casting slidificatin is analysed fr tp feeder and side feeder in gating system design. Casting simulated with tp feeder is shwn in Fig.3. Temperature distributin in part and in neck f feeder is C and 535. C whereas in case gating design with side feeder, temperature in casting sectin t feeder neck t feeder increases (56. C t C) and als side feeder feeds melt in mre laminar way.thus in present case side feeder is selected fr further casting study in terms f temperature distributin, slidificatin time, liquid fractin, htspt, shrinkage prsity and cld shut in casting. Gating system cmpnents are redesigned with center sprue and side feeder t get mre unifrm cling and shrinkage prsity free casting. The partial directinal slidificatin is btained with single side feeder. Tw side feeders alng with cpper sleeve(2.8mm thick) results in cmplete directinal slidificatin frm part t feeder neck t feeder(fig.4.) is used in further study. 3. EFFECT OF GATING RATIO By keeping all ther prcess parameters cnstant, gating rati and melt temperature are varied t study its effect n casting. With the abve design cnfiguratin (Fig.4) the effect f variatin f gating rati i.e. 1:2:2, 1:3:3 and 1:4:4 n casting quality is explred with melt puring temperature at 68 C. Gating system with 1:2:2 gating rati:simulatin result btained is as shwn in Fig.5 belw. It is bserved that the feeder is feeding t cmplete casting and the sequence f slidificatin is part-neck f feeder and lastly, feeder (Fig.5). As per liquid melt flw, it gets discnnected frm feeder at ne stage and due t that it is pssible t have shrinkage prsity at that psitins (Fig.5 ).It results in fill time f 1.51 secnd and slidificatin time f 1.73 minute.casting desn t shw pssibility f cld-shut. Gating system with 1:3:3 gating rati: Slidificatin simulatin results btained with gating rati f 1:3:3 are as shwn in Fig.6.It shws that, casting slidificatin takes place frm part twards feeders and liquid fractin reduces during slidificatin prcess. This indicate lwer liquid fractin at few psitins. Fig.3 Slidificatin f casting with tp feeder and side feeder. Fig.4 Design with tw side feeders and sleeves 56 TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA

4 Fig.6 Slidificatin fr gating rati f 1:3:3with temperature distributin and liquid fractin. Fig.5 Slidificatin fr gating rati f 1:2:2, with temperature distributin and liquid fractin. It is having fill time f 1.51 secnd and slidificatin time is 1.74 minute. Hwever pssibilities f ht spt exist at lwer level than earlier case f gating rati 1:2:2. Casting des nt have the pssibility f cld-shut. Gating system with 1:4:4 gating rati: simulatin results btained with gating rati f 1:4:4 are as shwn in Fig.7 belw. With gating rati f 1:4:4, Fig.7 shws temperature rise twards feeder neck t feeder. Casting cling takes place frm this part twards feeders and liquid fractin is apprximately nil (Fig.7 during slidificatin. This shws almst n chances f htspt and shrinkage prsity. 4. EFFECT OF MELT TEMPERATURE The cast aluminium ally LM4 is having liquidus temperature f 582 C and slidus temperature f 574 C Fig.7 Slidificatin fr gating rati f 1:4:4, with temperature distributin and liquid fractin. TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA 57

5 with difference f nly 8 C. T find the effect f melt temperature n casting, the melt puring temperature is increased in steps f 3 C, and bservatins are made fr temperature f 612 C, 642 C, 672 C, 682 C, 72 C, 732 C. The respnse is measured in terms f ht spts/shrinkage prsity, slidificatin time(cling effect / temp.) and cld-shut defect ccurrence. The simulatin utcme fr melt temp. 612 C, 642 C is as shwn in Fig.8 The simulatin utcme fr melt temperature 672 C, 682 C are as shwn belw in Fig.9, and Fig.9. When the cmpnent is cast with melt puring temperature f 672 C and 682 C, further reductin in liquid fractin is cntinued. The simulatin figures 9 (a, shws that defect-free casting can be btained fr pur temperature f 672 C. At higher pwer temperature f 682C als, prsity and ht spt defects are absent, as shwn in figure 9 (c,d). In case f melt with temperature 72 C and 732 C, during casting slidificatin n ht spt/shrinkage prsity psitins were fund. Hence behavir fr liquid fractin is nt shwn separately. S it is checked fr its temperature distributin and that the part is cling twards feeder is cnfirmed. The simulatin utcme fr melt temperature 72 C, 732 C is as shwn in Fig.1. It desn t include htspt utput fr abve temperature. 5. RESULT AND DISCUSSIONS Psitining the sprue at the center f the casting prvides melt flw at mre equal rate and result in very clse temperatures n bth sides f sprue in the cmpnent as seen frm Fig.2. It results in symmetrical cling n ppsite sides. In case when sprue lcatin is at ne side, it gives mre difference in cling rate at ppsite psitin t sprue, results in different cling rate. This happen as there is fall in temperature and increase in viscsity while melt reaches t ppsite end. Hence sprue psitin at center f casting is used further. c) d) Fig.8 Casting pured with melt temperaturef 612 C, results in htspt slidificatin time fr different psitins; Casting with melt temp. 642 C shws, c) htspt d) slidificatin time. Fig.9 Casting pured with melt temp. 672 C,results int htspt slidificatin time fr different psitins; Casting with melt temp. 682 C, shws c) htspt d) slidificatin time fr different psitins. 58 TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA

6 Effect f gating rati: Fig.5 shws that with gating rati 1:2:2, higher temperature gradient twards feeder is btained, but still there is pssibility f liquid fractin at three different psitins in casting during slidificatin. It is due t insufficient melt feeding during metal shrinking.fig.6 shws that when gating rati f 1:3:3 is used, in additin t temperature gradient twards feeder, % f liquid fractin during slidificatin is reduced, but nt remved. Here due t increase f gating rati, mre melt is fee during cling prcess, but it is still insufficient. Fig.7 shws that when gating rati is increased t 1:4:4, mre refined temperature distributin is bserved during slidificatin. Liquid fractin prblem is reslved cmpletely. The pssibility f ht-spt (shrinkage prsity) is almst nil. This happens as mre quantity f melt is feed with respect t fill time. Quantity f metal shrinkage is equal t the amunt f melt fed thrugh feeder and gating system. At the same time it result in fall f yield by small percentage. Fig.1 Casting pured with melt temp. 72 C, slidificatin time fr different psitins; Casting with melt temp. 732 C, slidificatin time fr different psitins. Tp feeder results in casting slidificatin with temperature in casting part higher than temperature in feeder neck (Fig.3). i.e. temperature gradient des nt increase twards feeder neck. In cntrast, in side feeder design, temperature gradient increases twards feeder. That results in directinal slidificatin twards feeder. It is bserved that side feeder wrk mre effectively than tp feeder. Effect f melt temperature: In case f casting with melt puring at 612 C(Fig.8. a and,liquid fractin during slidificatin is mre and verall, the cmpnent cls early due t high resistance t melt flw and lss f heat during the perid f increase viscsity. With melt pur temperature 642 C (Fig.8 c and d), effect f liquid fractin slightly reduces and temperature level f cmpnent increases. When melt with pur temperature f 672 C is used (Fig.9 a and, liquid fractin further reduces with increase f temperature. At a higher puring temperature f 682 C, abut 1 C mre than the melting temperature f the LM4, ally, ptimum distributin f temperature is btained and the simulatin figure shws that the casting is free frm cld shut and prsity. Fig.1 shws the simulatin figure f the casting with melt puring temperature f 72 C and 732 C, as temperature is mre w.r.t. earlier cases, fluidity is increased and it feeds cavity withut liquid fractin defect. But as gd quality casting is btained at 682 C puring temperature, there is n need t g fr higher temperature melt puring. It may increase gas prblem during prcess. S it is recmmended t g fr melt temperature f 682 C fr btaining casting with minimum defects. TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA 59

7 CONCLUSIONS The casting is designed with cnsideratin f muld layut. AutCAST-X1 with FLOW+ mdule is used t study the effect f gating design and melt puring temperature n casting quality. By simulating castingprcess the results btained are discussed and fllwing cnclusins are drawn: i. Sprue psitin shuld be placed at center f hallw cylindrical shape casting, which gives mre unifrm cling than placing it t ne side f cmpnent. ii. Fr feeder design, use side feeders instead f tp feeders as it prvides fine directinal slidificatin frm cmpnent t feeder neck t feeder during cling. iii. As gating rati is increased, the liquid fractin during slidificatin reduces which makes casting mre free frm shrinkage prsity and cld-shut defects. iv. As melt pur temperature is increased, ht spt/shrinkage prsity, cld shut defect frmatin pssibilities are minimized t greater extent. It gives better results at 682 C melt pring temperature in present case fr LM4 casting. REFERENCES: 1. B. Ravi, D. Jshi, Feedability analysis and ptimizatin driven by casting simulatin, Indian fundry Jurnal, April Himanshu Khandelwal, B. Ravi, Dipankar, Tabletp Fundry fr Training, Research and Small Enterprises, Indian fundry jurnal, Vl. 6 N.2 (Feb. 214), pp S.Savithri. R.Vaidya, Muld filling and slidificatin simulatin f multicavity mulds, Indian fundry Jurnal, ISSN , Vl.62, Issue4, April 216, pp Omer Savas, Ramazan Kayikci, Applicatin f Taguchi methds t investigate sme factrs affecting micrprsity frmatin in A36 aluminium ally casting, Science Direct, Materials and Design 28 (27) Vsniaks, Gerge Christpher, Vasilis, Numerical simulatin f sand casting f an aluminum part, Annals f nd DAAAM fr (211) &Prceedings f the 22 Internatinal DAAAM Sympsium, Vlume 22, N. 1, ISSN Murat Clak, Selcuk Sirin, et.al, Effect f dimensinal scaling n casting sundness f sand cast A36 Al ally, Eur st TecS-213, 1 Internatinal Research/Expert cnference, June 27-28, 213, pp S.Santhi, S.B.Sakari, D.Hunumath Ra, S. Sundarrajan, Shrinkage prsity estimatin f cylindrical shape cast aluminium cast aluminium allys,indian fundry jurnal, Vl.6/3, P.N.Ra, Manufacturing Technlgy Vlume-I,Tata rd McGraw-Hill Publ., 3 edi B. Ravi, Metal Casting-cmputer aided design and st analysis, PHI Publ., 1 edi, "Casting, Vlume 15,ASM Handbk,July User Manual, AutCAST-X1", 3D Fundry Tech Pvt. Ltd., Mumbai, India,January TRANSACTIONS OF 65th INDIAN FOUNDRY CONGRESS 217, KOLKATA