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南京理工大学泰州科技学院毕业设计(论文)外文资料翻译系部： 机械工程及自动化 专 业： 机械工程及自动化 姓 名： 赵浩冉 学 号： 05010149 外文出处： METALURGIJA 47 (2008) 1, 51-55 附 件：1.外文资料翻译译文；2.外文原文。 指导教师评语：译文比较正确地表达了原文的意义、概念描述基本符合汉语的习惯，语句较通畅，层次较清晰。翻译质量良。 签名： 年 月 日附件1：外文资料翻译译文B. KOSEC 刊号 0543-5846 METABK 47151-55（2008） UDCUDK621.74.043:669.71=111铝合金压铸模的失效分析 收到： 2006-12-23 接受： 2007-04-20摘要铝合金压铸模失效，由很大不同同时也很重要的因素影响。材料的选择、模具的设计及循环工作所产生的热应力疲劳（热检查中，工作表面温度场的强度和均匀性的测试是通过温度测量仪检查），以及模具初始不均匀的温度导致铝合金模具在压铸过程中失效或形成裂缝。在目前调查中，失效和裂缝通过非破坏性的金相检验方法分析。关键词 压铸 工作表面 铝合金 温度场 失效分析导言压铸是最具有成本效益且技术方法简单，用来铸造先进、准确的大规模铝合金零部件1 。铝合金压铸件直至最后安装，需要很少加工。世界各地所有铸件大约有一半由铝合金制造，铝合金压铸件广泛用于汽车零部件和其他货品2 。表1显示了压铸与冲压、锻造、砂型铸造、 硬模浇铸、塑料成型的九种参数比较3。 铝合金压铸模失效，因为许多不同，同时也很重要的因素影响。这个因素有两个基本类型4 ：模具的制造因素，和形成过程因素。铝合金压铸件的工作寿命长短对于经济生产是至关重要的5 。对于资金和生产时间来说，更换模具都是昂贵的。Table1. Comparison of nine parameters of the die-casting and other processes 3表1. 压铸的九种参数和其他进程比较比较九种参数比较冲压锻造沙模铸造硬模浇铸塑料成型1 成本加工较低较低生产加工较低劳动生产加工较低基本上较高2 设计柔性度外形更复杂外形更复杂壁可能更薄壁可能更薄，需要较少的草案要大的多3多功能性设计可能更好较少的加工较多的功能较少的加工较多的功能较少的加工较多的功能更多的用途4 偏差较紧密较紧密较紧密较紧密较紧密5 壁厚较大的变化较薄较薄较薄较薄但有同样的强度6 表面加工一般平滑平滑平滑一般7 材料损耗少少少少少8 强度取决于设计拉伸较低相当与合金相当与合金要大的多9 重量取决与设计轻的多轻的多较少较少最常见的铝合金压铸模的失效一般可以分为四个基本分类：热检查、角裂、棱角尖锐锋利、磨损或被侵蚀。人们普遍认为：影响模具寿命的一个主要因素是热检查，裂纹萌生和传播发生过程中导致模具表面热应力疲劳 6-8 。压铸专家（设计师， 制造商和运营商）可能在一定程度上影响有些模具的失效因素9。这些因素包括10 ：-设计-材料选择 -热处理 -经营运转 -操作和使用压铸模具测试在我们的调查分析工作中，对一个典型的铝合金压铸模进行了分析11 。整个压铸机如图1所示，图2是压铸模测试机的定模。热工作模具钢必须具备优良的性能12 。模具材料要求的性能列于表213。测试模具由BOEHLER W300 ISODISC热加工工具钢制造14， 它广泛用于各种热加工工具和模具。生产者给出了BOEHLER W300 ISODISC钢的热学和力学性能。AlSi9Cu3铸铝合金的熔点大约是在593，铸造温度约更高50，因此从室温升到大约700的温度范围在事例性能的分析报告中很重要。BOEHLER W300 ISODISC钢在室温（20）下的密度大约是7800 ，它随温度升高而减小。截至温度为700 ，密度降至约200 。这种钢由于热传导率（从19.2至26.3 ），温度相对较低且近乎线性的升高，且不断成比例的扩散热量（整个时间大约是在） 。比热随着温度升高而增长，从456 到587 。伸长率系数从（温度为20）到（温度为700）缓慢增长，而弹性系数随着温度的升高从211 增到168。Figure1. Die-casting machine图1. 压铸机温度测量与分析当铝合金熔化时，模具工作表面扩张，然后随着热量扩散到模具表面的下面，温度降低了，表面紧缩15 。热铝合金和模具的温差越大，模具表面将扩大和收缩的越厉害，然后模具表面会出现热处理的作用16 。由于模具表面的压力与模具温度成反比例，而且模具保持一定热量是经济的，所以模具保持一定热量是件好事。铝合金压铸模应预热大约240至300。经验表明：增加模具的工作温度，从 205至315 ，模具的生产量可能会增加一倍17 。 定模工作表面所要求的初始温度场的强度和均匀度通过温度测量仪检查 18,19，温度测量仪获得了相对简单的模具的几何和温度记录（热图像）。与应用仅限于非常小的表面的光学温度计相比，它通过温度摄像头检查对象（图3）。 相机的视野是大约水平30，垂直20的范围。在这一视野的30.000温度图像信息可以通过温度摄像头得到。而单一细节的几何分辨能力取决于相机与目标的距离。 Figure2. Fixed half of the testing die-casting die图2. 压铸模测试机的定模定模工作表面的温度测量贯穿了模具的预热期和模具的整个工作表面最初的运行期。（温度大约240） 模具表面的温度测量和温度摄像头的校准，通过Ni-NiCr热电偶接触实现，42分钟时测量到的61.2 （见表3 ）是定模表面的标志点。几秒钟后没有校准的温度摄像头（有效值为1.0的发射率）与实际温度67.1集于一点。这两个温度测量的比率表示发射率的值为0.91 。该发射率由每次实验的测量确定。Figure3. Position of the thermographic camera图3. 温度摄像头的位置如图4所示的温度记录图象，只是连续图像的一部分。压铸模工作表面的温度分布由温度热像仪上的颜色所显示。黑白温度记录仪有16个不同的颜色， 不同颜色之间的过渡表现出温度的差异，而几何细节不太清楚。对于每一个温度热像仪，图像是非常重要的（见表3 ） 。左侧的第一个温度热像仪与其之后完成的第二个温度热像仪，直接比较了在模具表面温度预热过高时显示的连续的颜色。只有同温度范围的彩色温度热像仪可直接比较。Table2. Testing case-cronological flow of the preheating process表2. 预热过程测试操作时间/min表面最大温度预热0-开始测量4091校准温度测量仪42-开模（1）60125增加高温油90开模190150开模（2）测量结束250161图4中的温度热像仪（左）显示的温度范围为90至161 ，黑色区域低于90。右侧的温度热像仪同左侧温度热像仪一样 ，但温度显示范围较低，介于90 至124Figure4. Working surface of the fixed part of testing die-casting die (Figure1 and Table3).图4. 压铸模定模工作表面的测试（图1和表3 ）Figure5.Working surface of the testing die-casting die. Surface pits and cracks at identification marks.OM图5. 压铸模工作表面的测试。 表面凹坑和裂缝识别标记。在铸造厂，类似模具的预热时间要比我们的测试短得多（最多可达两个小时） 。此外，我们的测试测量后增加了热循环油（温度约250 ），约 1小时30 l/min（铸造厂通常使用）至60 l/min 。失效分析定模压铸不到一千次,工作表面显示，并确定出现了裂缝 。其中有些通过使用放大镜甚至肉眼也可以清楚地观察到。在我们的实验范围内，通过光学显微镜（OM）和电子显微镜（SEM），非破坏性的金相检验分析检验聚合物铸件也得到应用 20 。测试模定模容易凸出的部分（高超过500）用砂纸抛光，然后用光学显微镜审查。铸件非常尖锐，即使是表面上的小细节和微观成分可以很容易用光学显微镜以及电子显微镜观察到。高深度的电子显微镜可以观察到对象的三维图像22。当然，模具表面坑凹部分，是第一条裂缝开始的地方，没有机器可供抛光和显微镜可观察结论铝合金压铸模产生裂纹，由于有很大不同，同时也很重要的因素导致。其中一些影响模具失效的因素一定程度上可由压铸专家控制。从温度热像仪的显示上可以清楚看到， 如果加热方法和模具设计不变，所需要的温度场的强度和均匀性是不可能改变。在压铸过程中的循环负荷的主要来源是变化的温度; 其他负荷的影响相对微不足道。 因此，在第一阶段的解决方案是应该改变加热/或冷却的渠道的位置，即使它们更贴近模具的工作表面，有利于更高，更均匀的供暖。参 考 文 献1 S.Kalpakjian, Tooland Die Failures-Source Book, ASM International, MetalsPark, Ohio, 1982.2 R.M. Lumley, R.G. ODonnel, D.R. Gunasegaram, M. Girord , Heat Treating Progress ,6 (2006) 5, 31 37 . 3 S.S. Manson, Thermal Stress and Low-Cycle Fatigue , McGrawHill, New York,1996.4 L.A. Dobrzanski, Technical and Economical Issues of Materials Selection, Silesian Technical University, Gliwice,1997.5 K.Strauss , Applied Sciencein the Casting of Metals , Pergamon Press, Oxford,1970.6 J.V. Tuma, J. Kranjc, Forschung in Ingenieurwessen Engineering Research , 66 (2001) 4, 153156.7 L. Kosec, F. Kosel, Mechanical Engineering Journal, 29 (1983) 7-9, 151158.8 B.Smoljan, Journal ofMaterials Processing Technology,155(2004)11, 17041707.9 P.F.Timmins, Fracture Mechanism and Failure Controlfor Inspectors and Engineers, ASM International, Materials Park, Ohio, 1995.10 Handbook of Case Historiesin Failure Analysis, Volume1, ASM International, Materials Park, Ohio, 1992.11 B.Kosec, Metalurgija, 45(2006)3, 217.12 I. Vitez, Ispitivanje mehani kih svojstava metalnih materijala, Sveuilite J.J. Strossmayera u Osijeku, Strojarski fakultetu Slavonskom Brodu, SlavonskiBrod, 2006.13 R.Ebner, H.Leitner, F.Jeglitsch, D.Caliskanoglu, Proceeth International Conference on Tooling, Leoben,dings of 5 (1999)312.14 Bohler Edelstahlhandbuch auf PCV2.0, Kapfenberg, 1996.15 B.Kosec, G.Kosec, Metall, 57 (2003)3, 134-136.16 L.A.Dobrzanski, M.Krupinski, J.H.Sokolowski, Journal of Materials Processing Technology, 167(2005)2-3, 456462.17 B.Kosec, G.Kosec, M.Sokovic, Journal of Achievements in Materialsand Manufacturing Engineering, 20(2007)1-2, 471475.18 L.Masalski, K.Eckersdorf, J.McGhee, Temperature Measurement, John Wiley&Sons, Chichester, 1991.19 H. Haferkamp, F.W.Bach, M.Niemeyer, R.Veits, Aluminium, 75 (1999)11, 945953.20 B.Kosec, M.Sokovic, G.Kosec, Journal of Achievements in Materials and Manufacturing Engineering, 13 (2005),339-342.21 R.Celin, J.Tusek, D.Kmetic, J.V.Tuma, Materials Science and Technology, 35(2001)6, 405408. 22 I.Anzel, Metalurgija, 39(2000)3, 237-241.23 B.Kosec, J.Kopac, L.Kosec, Engineering Failure Analysis, 8(2001)4, 355 359.B. KOSECFAILURES OF DIES FOR DIE-CASTING OF ALUMINIUM ALLOYSReceived Prispjelo: 2006-12-23Accepted Prihvaeno: 2007-04-20Preliminary Note Prethodno priopenjeINTRODUCTIONDie-casting is the most cost efficient and technicaleasy method of casting sophisticated and accurate alu-miniumalloyspartsingreat-scaleseries?1?.Aluminiumalloys die-castings require little machining prior the fi-nal installation.Approximately half of all castings worldwide madeof aluminium alloys are manufactured in this way areusedforawiderangeofautomotivepartsandothercon-sumer goods ?2?. The comparison of nine parameters ofthe die-casting versus stamping, forging, sand casting,permanent mold casting and plastic molding ?3? is pre-sented in Table 1.Aluminium alloys die-casting dies fail because of anumber of different and simultaneously operatingstresses. The stresses are of two basic kinds ?4?: stressescreated by the manufacturing of the die and stressesformed by the exploitation process.Alongdieworkinglifeisofessentialimportancefortheeconomicalproductionofaluminiumalloysdie-castings?4,5?.Thereplacementofadieisexpensivein both money and production time.The most frequent failures of aluminium alloysdie-casting dies can generally be divided into four basicgroups ?1?: heat checking, corner cracking, sharp radiior sharp edges cracking, and cracking due to wear orerosion. It is generally agreed that one of the principalcauses of termination of die life is heat checking, whichoccurs through a process of crack initiation and propa-gation induced by the thermal stress fatiguing of a diesurface ?6-8?.Some of the factors that affect die failures may becontrolled to some extent by the die-casting experts (de-signers, manufacturers and operators) ?9?. These factorsinclude ?10?:- design,- materials selection,- heat treatment,- finishing operations, and- handling and use.TESTING OF DIE-CASTING DIESIn the frame of our investigation work a complexanalysis of a typical dies for die-casting of aluminiumalloys has been carried out ?11?. The whole die-castingmachine is shown in Figure 1, and the fixed half of thetesting die-casting die is in Figure 2.METALURGIJA 47 (2008) 1, 51-5551Die-casting dies for casting of aluminum alloys fail because of a great number of different and simultaneouslyoperating factors. Material selection, die design, and thermal stress fatigue generated by the cyclic workingprocess (heat checking), as well as to low and inhomogeneous initial die temperature contribute to the failuresand cracks formation on/in dies for die-casting of aluminium alloys. In the frame of the presented investigationwork the intensity and homogeneity of the temperature fields on the working surface of the testing die werechecked through thermographic measurements, and failures and cracks on the working surface of the die wereanalysed with non-destructive metallographic examination methods.Key words: die-casting, working surface, aluminium alloy, temperature field, failure analysisOteenje kalupa za lijevanje aluminijskih legura. Do oteenja kalupa za lijevanje aluminijskih leguradolazi zbog istodobnog utjecaja brojnih razliitih radnih imbenika. Kod kalupa za lijevanje aluminijskih leguraizbor materijala, konstrukcija kalupa, zamorno termalno naprezanje zbog ciklikog radnog procesa te niska inehomogena polazna temperature kalupa doprinose oteenju i nastajanju pukotina. U okviru ovog istraivan-ja kontroliran je intezitet i homogenost temperaturna polja na radnoj povrini ispitanog kalupa pomou termo-grafskih mjerenja, a oteenja i pukotine na radnoj povrini analizirani su nedestruktivnim metalografskimmetodama.Kljune rijei: lijevanje u kalup, radna povrina, aluminijska legura, temperaturno polje, analiza oteenjaISSN 0543-5846METABK 47(1) 51-55 (2008)UDC UDK 621.74.043:669.71=111B. Kosec, Faculty of Natural Sciences and Engineering, University ofLjubljana, Ljubljana, SloveniaThehotworkdiesteelmusthaveexcellentproperties?12?. Requested properties and damage mechanisms ofthe die material are shown in Table 2 ?13?.ThetestingdiewasmanufacturedfromtheBOEHLER W300 ISODISC ?14? hot work tool steel,which is widely used for all kinds of hot working toolsand dies.ThethermalandmechanicalpropertiesofBOEHLER W300 ISODISC steel are given by the pro-ducer.Theliquidustemperatureofcastedaluminiumal-loy AlSi9Cu3 is approximately of 593 C, and castingtemperature is approximately 50 C higher, thereforethepropertiesinthetemperatureintervalfromtheambi-ent temperature up to approximately 700 C are impor-tant for the analysis of the discussed case.The density of BOEHLER W300 ISODISC steel atambient temperature (20 C) is approximately of 7800kg/m3,anditdecreaseswithhighertemperature.Uptothetemperature of 700 C it drops for about 200 kg/m3. Thissteelhasarelativelylowandnearlylinearincreasingtem-perature dependent heat conductivity (from 19,2 to 26,3W/mK), and proportionally constant thermal diffusivity(the whole time it is approximately of 5?10-6m2/s). Spe-cific heat is increased with higher temperature and it isfrom 456 to 587 J/kgK, respectively, for the boundaryvaluesofthechosentemperaturerange.Thelinearcoeffi-cientofelongationslowlyincreasesfrom10,7?10-6/K(at20 C) to 13,2?10-6/K (at 700 C), while the modulus ofelasticity, with boundary values of 211 and 168 GPa, de-creases with the increase of temperature.TEMPERATURE MEASUREMENTSAND ANALYSISWhen the melts wets the die active working surfacethedieexpandsandthencontractsasthesurfacetempera-ture is lowered by the diffusion of heat into the steel be-52METALURGIJA 47 (2008) 1, 51-55B. KOSEC: FAILURES OF DIES FOR DIE-CASTING OF ALUMINIUM ALLOYSTable 1. Comparison of nine parameters of the die-casting and other processes ?3?Compared withNine points ofcomparisonStampingsForgingsSandcastingsPermanent mold ca-stingsPlastic molding1 CostLower machiningLower finalLower productionand machiningLower labor, produc-tion and machiningGenerally higher2 Design flexibilityMore complex sha-pesMore complexshapesThinner wall sec-tions possibleThinner wall sectionspossible, less draft re-quiredMuch greater3 FunctionalversatilityBetter designs pos-sibleMore versatile withless machiningMore versatile withless machiningMore versatile with lessmachiningMany more uses4 TolerancesCloserCloserCloserCloserCloser5 Wall thicknessGreater variationsThinner sectionsThinner sectionsThinner sectionsThinner sections forthe same strength6 Surface finishWider varietySmootherSmootherSmootherWider variety7 Material wasteLessLessLessLessLess8 StrengthDepends on designLower tensileGreater with samealloyGreater with same al-loyMuch greater9 WeightDepends on designLighterLighterLessLessFigure 1. Die-casting machineFigure 2. Fixed half of the testing die-casting dielow the surface of the die ?15?. The greater difference be-tween the temperature of the die and that of the hot alu-minium alloy shot into the die, the greater will be the ex-pansionandcontractionofthediesurface,andsoonerthedie surface will show the effect of heat checking ?16?.Since the stresses produced on the die surface are in-versely proportional to the die temperature, it is goodpractice to keep the dies as hot as it is economical. Alu-minium alloys die-casting dies should be preheated toapproximately 240 to 300 C. Experience has shownthat by increasing the die operating temperature from205 to 315 C, die production may be doubled ?17?.The required intensityandhomogeneityofthe initialtemperaturefieldontheworkingsurfaceofthefixeddiehalf was examined with thermographic measurements?18,19?. The testing thermographic measurements werecarried out on a die of relatively simple geometry andsimple thermographs (heat images) were obtained.In comparison with optical pyrometers, which appli-cation is limited to the very small surface, investigatedobject is enabled by thermographic camera (Figure 3).Camera field vision is of about 30 horizontally and of20 vertically. Within that field of vision the tempera-ture image of about 30.000 information points on tem-perature were obtained with the camera. The geometricresolving power of single details depends on the dis-tance of camera to object.On the working surface of the fixed die halfthermographic measurements have been carried out inthe die preheating period to the initial operating temper-ature (approximately 240 C and homogeneous throughthe whole working surface of the die).Checking temperature measurements on the die sur-face and calibration of the thermographic camera havebeen carried out using a contact Ni-NiCr thermocoupleand the temperature of 61,2 C was measured at time of42 min (Table 3) in the marked point on the surface ofthe fixed die half. A few seconds later not calibratedthermographic camera (with the virtual value ofemissivity equal 1,0) was centered to the same pointwith the virtual temperature of 67,1 C. The ratio be-tween both measured temperatures represents the valueof emissivity of ? = 0,91. The emissivity has to be deter-mined experimentally before each measurement.Thermographs, shown in Figure 4, are just parts oflongercontinuousprints.Thetemperaturedistributiononworking surface of the die-casting die is shown by thecolour on the thermographs. Black and white thermo-graphs have been coloured with sixteen distinct colours.Distinct transitions between colours show the differenceintemperature,whilethegeometricdetailsarelessclear.For each thermograph, the time of formation of im-age print is very important (Table 3). The firstthermograph on the left is presented with extended col-our scale to be directly comparable to the second whichwas done later, when the surface temperatures of thepreheated die was significantly higher. Only the sametemperature range coloured thermographs can be di-rectly compared.Thermographs (left) in Figure 4 are presented for thetemperature range of 90 to 161 C, with black (uncol-oured) regions below 90 C. Right thermograph is thesame as the left thermograph (1), but it is presented inthe lower temperature range between 90 and 124 C.METALURGIJA 47 (2008) 1, 51-5553B. KOSEC: FAILURES OF DIES FOR DIE-CASTING OF ALUMINIUM ALLOYSTable 2.Damage mechanisms and requestedproperties of die materialDamagemechanismRequested propertyHigh mechanicalloadingHigh hardnessSuitable fracture toughnessHigh mechanicalloading at elevatedtemperaturesHigh hot hardnessHigh thermal stability of the microstruc-tureRepeated mechani-cal loading (fatigue)High hardnessHigh fatigue resistanceFine microstructureLow content and small size of internaldefectsWearAbrasionHigh hardnessHigh volume fraction, optimum size anddistribution of hard wear resistant parti-clesAdhesionHigh hardnessOxide layer at the surfaceLow chemical reactivity between tooland work materialSurfacefatigueHigh hardnessHigh fatigue resistanceHigh temperatureHigh thermal stability of the microstruc-tureHigh oxidation resistanceThermal cyclingHigh thermal stability of the microstruc-tureHigh hardness at elevated temperaturesHigh creep resistanceHigh resistance against plastic cyclingLow thermal expansionHigh oxidation resistanceFigure 3. Position of the thermographic cameraIn the foundry praxis the preheating time is for simi-lardiesmuchshorterthanitwasbyourtests(maximallyup to two hours). Furthermore, the flow of heating oil(with the temperature approximately 250 C) was in-creased during our test measurement after approxi-mately 1 hour from 30 l/min (in the foundry praxis usu-ally applied) to 60 l/min (for 100 %).FAILURE ANALYSISThe cracks appeared on the working surface of thefixed die half after less than thousand shots were re-vealed and identified with penetrants. Some of themwere also clearly seen by the use of magnifying glass oreven by visual observation. In the frame of our experi-mental work also non-destructive metallographic exam-ination by optical microscopy (OM) and by scanningelectron microscopy (SEM) of polymer replicas was ap-plied ?20?.Readily accessible convex parts of the fixed half ofthe testing die were polished with fine grade (higherthan500)emerypaperanddiamondpasteandexaminedin optical microscope. Polymeric foils were used to takeimprintsfromthesurfaceofthepreparedspots?21?.Thereplicasobtainedweresosharpthatevensmalldetailsofthe surface e.g. microstructure constituents could easilybe observed with an optical microscope as well as ascanning electron microscope. High depth of field char-acteristics of scanning electron microscopy resulted in asharp three-dimensional image of the observed object?22?. Naturally, concave parts of the die surface, wherethe first long cracks initiated, were not accessible formachine polishing and microscope observation.Thecontourlinesoflettersandnumbersofanidenti-fication marks are well rounded. However, many cracksstarted from these signs and their lengths are within 2054METALURGIJA 47 (2008) 1, 51-55B. KOSEC: FAILURES OF DIES FOR DIE-CASTING OF ALUMINIUM ALLOYSTable 3.Testing case - cronological flow of thepreheating processOperationTime/ minMaximal surfacetemperature/ CStart of preheating0Start of measurements4091Calibration of thermographiccamera42Opening of the die (1)60125Increasing of heating oil flow90Opening of the die190150Opening of the die (2)End of measurements250161Figure 4. Working surface of the fixed part of testing die-casting die (Figure 1 and Table 3). Preheating process. Thermo-graphs. At the beginning (1), and at the end (2 initial temperature field) of the die preheating processFigure 5. Working surface of the testing die-casting die.Surface pits and cracks at identification marks.OMto 200 ?m range ?23?. Based on the shape and type ofpropagationtheycanbeattributedtoheatchecking(Fig-ures 5 and 6).CONCLUSIONSCracking on/in die-casting dies of aluminium alloysis caused by a number of different and simultaneouslyoperating factors. Some of them that affect die failuresmay be controlled to some extent by the die casting ex-perts.The failures: cracks and pits observed on the work-ing surface of the testing die-casting die belong to heatchecking initiated at identification marks, and crackingin corners, sharp edges and transitions.It is clearly seen from the presented thermographs,that the required temperatures and homogeneity of thetemperature field of the discussed case are not possibleto reach without changing of both: the heating methodand the die design. In the process of the die-casting theprimary source of loading is cyclic variation of the tem-perature; the influence of other loads is relatively insig-nificant. Therefore in the first stage a solution of theproblemshouldbeinchangingofthepositionofheatingand/or cooling channels, i.e. their closer shifting to theworking surface of the die, so the higher and more ho-mogeneous heating should be reached.REFERENCES?1?S. Kalpakjian, Tool and Die Failures - Source Book, ASMInternational, Metals Park, Ohio, 1982.?2?R.M. Lumley, R.G. ODonnel, D.R. Gunasegaram, M. Gi-rord, Heat Treating Progress, 6 (2006) 5, 31 37.?3?S.