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JMaterSciTechn01，V0124 No1，2008Thin-Wall Aluminum Die-Casting Technology for Developmentof Notebook Computer HousingChang-SeogKangt，Jae一k Cho，Chang-Yeol Jeong,SeWeon Choi and Young-Chan IGmKorea Institute of Industrial Technology，Gwangju，KoreaManuscript received September 3，200765Siliconbased aluminum casting alloys are known to be one of the most widely used alloy systems mainlydue to thei r superior castlng characteristics and unique combination of mechanicaI and physicaI propertiesHowevermanufacturing of thinwalled aluminum diecasting components，Iess than I0 mm in thicknessisgenerally known to be very difficult task to achieve aIuminum casting alloys with high fluidityThereforeinthis studythe optimal diecasting conditions for producing 297 mm x 210 mm x 07 mm thinwalled aluminumcomponent was examined experimentally by using 2 different gating systems，tangential and split typeandvent designFu rthermore，computational solidification simulation was also conductedThe results showedthat split type gating system was preferable gating design than tangential type gat ang system at the pomtof view of soundness of casting and distortion generated after solidificationIt was also found that propervent design was one of the most important factors for producing thinwaI|casting components because it wasimportant for the fullment of the thinwall cavity and the minimization of the casting distortionKEY WORDS：Aluminum；Thin-wall diecasting；Notebook computer housing；Cold chamberdiecasting machine1IntroductionAmong the aluminum casting alloysthe A1一Sibased alloy systems are one of the most widely usedalloy systems because of their unique characteristicssuch as 10w density，moderately high strength，andgood castability,etc1 3jRecently,the demand forlightweight alloys i11 electricelectronic and autoHIobile component housings using aluminum has beengreatly increased mainly because it is lightweight having high damping capacity and dent resistance conlpared to plasticsHoweverit is generally known that manufacturing of thinwall aluminum component with a thickness less than 10 mm by using high pressure die casting process is quite difficult due to its low fluidityThis leads to the liinit,ed application of the aluminumalloy in the fields of housing of electricelectroniccomponents such as notebook computer and cellularphone，etcTherefore，in this study，diecasting process technology for the production of thinwall aluminum components based on the investigation of theoptimal die design including runners and gating system and casting conditions was investigatedMoreover，experimental examinations of gating design el-fects on the fabrication processing of sound thinwallaluminum notebook housing with a thickness of lessthan 08 nlnl2ExperimentalPrior to the actual diecasting experimentcastingsimulation vcas conducted to set up the diecastingand melt conditionsDiecasting die made out ofH13 tool steel for the thinwall notebook housing insize of 210 Himx297 nlnl07 innl was designed andfabricated for the experiment As shown in Fig1、十 PhD，to whom co r11e8pondence should be addressedEmaih cskan97kitechrekrthe 2 different types of gating system，tangential typeand split type，were used for this investigationA commercial ALDCl2 aluminum diecastingalloy(A1一(9612)si一(15 35)Cu，Table 1)wasmelted up to 780。C and the die was heated up to230。C before the die castingThe major specifications of the cold chamber diecasting machine fFig2)，used for this study are shown in Table 2Molten aluminum alloy was injected into the die cavity underthe conditions of 035 ms in injection speed until theplunger traveled up to 370 Him in shot sleeve andthen the in 1iectionspeed was accelerated inearly tothe high injection speed of 20，25，303540 and45 ms fronl 370 inm to 390 Him in shot sleeveTable 3 shows the summary of diecasting conditions forthis investigation3Results and DiscussionThe solidi蠡cation simulation was conducted for 2different gate designs，tangential and split type priorto the diecasting experimentThe flow pattern andtemperature distribution during filling of aluminummelt with the gate designs studied are shown in Fig3It was found that both gate designs exhibited quiteuniform melt flow throughout the filling of the cavityHowever，the tangential type gate design resuited in the melt temperature dropped area f circlediil Fig3(a)at the last stage of filling while tile splittype gate design allowed the melt to fill the cavityabove the liquidus temperatureAs mentioned，actual diecasting experiments wereconducted for the notebook computer housing in sizeof 210 miD_297 nlnlX07 toniFigure 4 shows the resultant castings with varied high speed injection from20 to 45 ms while 10w speed injection was fixed to035 msAs shownboth gate designs allowed fillingthe casting with high speed injection of more than30 msHowever，less than 30 ms of high speedinjection failed to fill the thinwall cavityIt was 万方数据66 JMaterSciTechn01，V0124 No1，2008Table 1 Chemical compositions of ALDCl2 alloy(in wt pct)Table 2 Specification of diecasting machine5250 490 砂70Table 3 Diecasting experiment conditions780 230 20，25，30，35，40，45 035Fig1 Schematic illustration notebook housing(210 mmx297 IllIllXo8 nlm)and 2 different gate designs：(a)tangential type，(b)split typeFig2 High speed diecasting machine 万方数据EE、CQ芑凸JMaterSciTechn01，V0124 No1，2008Fig3 Simulation results of 2 different gate designs：(a)tangential type，(b)split typeFig4 Diecasting results by varying the high speed injection：(a)tangential type，(b)split typeDistance，mmFig5 Distortion of tangential and split type gating system after the removal of gatesalso found that the tangential type gate design wasnot able to 61l the overflow even at the highest injection speed used for this investigationMoreover，thetangential type gating system resulted in more distortion of the casting after the removal of the gate67In Fig5，the amount of distortion measured afterremoval of each gating system was displayedTheresult clearly showed that the tangential type gating system could resulted in more severe distortionthan split typeSince notebook housing fabricated inthis research was only 07 mm in thickness，the stressbuild up because of the shrinkage of casting after thecompletion of solidification was an important factorto consider for the mass production of the notebookhousingTherefore，it was concluded that the splittype gate design was better than the tangential typebecause of the aforementioned mattersHowevereven with split type gate design therewere casting defects such as flow line and misrun during diecastingTherefore，two major modificationswere introducedOne was the increase of the overflow and vent sizesThe volume of the overflow wasincreased about 70ffrom 4400 mm3 to 7500 mm3)and the overflow ingate length was also increased frOln135 mm to 30 mm in total length for the better flowof air in the die cavityMoreover，upper part of sleevewas machined to have inclined slope as shown in Fig6 万方数据68 JMaterSciTechn01，V0124 No1，2008Fig6 Schematic illustration of the inclined slope sleeveFig7 Thinwall notebook housing with a thickness of O7 millGate systemLocationFig8 The thickness of thinwall notebook housingto minimize the turbulence and air entrapment insideof the sleeve during in iection Because the sleeve WaSfilled with aluminum less than 30fminimum of 40of sleeve filling is recommended in die，casting process in fieldl resulting large amount of entrapped airand high turbulence during injection L4JAs the Fig6shows，the machined slope would help air inside of thesleeve to flow out more easily during in tha土iectionSOthe air entrapment in the melt would be minimizedWith-two modifications mentioned earlier，sound thinwall notebook housing casting with less defect WaSsuccessfiflly fabricated(Fig71There found to be lessflow line，crack and misrun defects in the castingThethickness of the casting was measured fFig81In leftfigure，the locations of the thickness measured and areshown and the right figure shows the nleasured thickEE、o亡芏。IuI万方数据JMaterSciTechn01，V0124 No1，2008ness of the castingThe thickness was found to bequite uniform and average thickness of 067 nlnl wasobtainedBecause the casting was so thin，less than 07 innl，the e 一iection fronlthedieafterlthe solidificationbecanlevery important Tbin wal casting could be bentor even cracked during the ejection；therefore，thenumber of ejector pin and its 1ay out were very criticalin die designMoreover，the use of die temperaturecontroller WaS also an important factor for fulfillmentof die cavity for thinwall diecastingIt was foIundthat without the die temperature controllerthe dieWaS not heated up SOfficiently even with more than20 times of injectionWhen the die did not be heatedup to appropriate temperature，the melt would berapidly cooled down when it injected inside of thecold die cavityAs a resultsevere casting defects ineluding misrun and cracks were exhibited without dietemperature contr014Conclusion(1)Between tangential and split,type gate designs，split type gating system WaS found to be better forthinwall diecasting because the melt flows more uniformly inside the die cavity(2)As the melt reached the ingate，the high speedinjection needed to be higher than 30 mSpreferably 45 msfor sound thinwall diecasting in size of69notebook computer housing(3)The thickness was uniform throughout thecasting and average thickness of 067 nUll was obtained(4)For thinwall aluminum diecasting，the location and the size of air vent and overflow were important factors for minimizing the flow line and inisrundefects in the casting(5)Inclined slope sleeve design WaS helpful for airentrapped inside of sleeve to flow out during injection(6)Because the casting volume WaS quite small，itis important to COntrol the die temperature 38 high 38possibleAcknowledgementThis work was supported by Korea Institute of Industrial Technology and Cwangju Metropolitan City through“The Advanced Materials and Components Industry Development Program”【23【4REFERENCESMicrostructure and Properties of Aluminum AllqysThe Japan Instof Light Metals，1991233GKSigworth：AFS TraIIS198391。7JEGruzleski and Bernard MClosset：AFS199013WGhlkington：Die Casting DefectsNADCA1997万方数据Thin-Wall Aluminum Die-Casting Technology forDevelopment of Notebook Computer Housing作者： Chang-Seog Kang， Jae-Ik Cho， Chang-Yeol Jeong， Se-Weon Choi， Young-Chan Kim作者单位： Korea Institute of Industrial Technology, Gwangju, Korea刊名： 材料科学技术学报（英文版）英文刊名： JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY年，卷(期)： 2008，24(1)引用次数： 0次参考文献(4条)1.Microstructure and Properties of Aluminum Alloys 19912.G K Sigworth 查看详情 19833.J E Gruzleski.Bernard M Closset 查看详情 19904.W G Walkington Die Casting Defects 1997相似文献(3条)1.期刊论文 Young-Chan Kim.Chang-Seog Kang.Jae-Ik Cho.Chang-Yeol Jeong.Se-Weon Choi.Sung-Kil Hong Die Casting Mold Design of the Thin-walled Aluminum Case by Computational Solidification Simulation -材料科学技术学报（英文版）2008,24(3)Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among thelightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficientfluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1 mm. Therefore, in this study, thin-walleddie casting of aluminum (Al-Si-Cu alloy: ALDC 12) in size of notebook computer housing and thickness of 0.8 mm was investigated bysolidification simulation (MAGMA soft) and actual casting experiment (Buhler Evolution B 53D). Three different types of gatingdesign, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled diecasting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thincavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point ofview of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with theactual die-casting and the casting showed no casting defects and distortion.2.外文期刊 Chang-Seog Kang.Jae-Ik Cho.Chang-Yeol Jeong Thin-Wall Aluminum Die-Casting Technology forDevelopment of Notebook Computer Housing Silicon-based aluminum casting alloys are known to be one of the most widely used alloy systems mainly due to their superiorcasting characteristics and unique combination of mechanical and physical properties.However,manufacturing of thin-walled aluminumdie-casting components,less than 1.0 mm in thickness,is generally known to be very difficult task to achieve aluminum casting alloyswith high fluidity.Therefore,in this study,the optimal die-casting conditions for producing 297 mm210 mm0.7 mm thin-walledaluminum component was examined experimentally by using 2 different gating systems,tangential and split type,and ventdesign.Furthermore,computational solidification simulation was also conducted.The results showed that split type gating system waspreferable gating design than tangential type gating system at the point of view of soundness of casting and distortion generatedafter solidification.It was also found that proper vent design was one of the most important factors for producing thin-wall castingcomponents because it was important for the fulfillment of the thin-wall cavity and the mi