Metal Casting Process

metal Casting ProcessMaterials and DesignPressure go away Casting ProcessExecutive SummarySince the discovery of the earths minerals, metal soak up process has played an important role in society. An integral part of every technological advance, stamps have allowed us to configuration equipment to feed our people, fight for democracy, build infrastructure and manufacture cars, trains and airplanes. In general, forms have been and will continue to be the disclose ingre runnt in the recipe for a better way of life. on that point ar various types of border process, such as sand- dramatis personae, permanent- figure out casting, investment casting and die-casting. Due to the words limitation, in this investigative study, only the development, technical challenges, recent findings, prospective direction, range of applications and shortcomings of pressure die-casting process will be discussed.IntroductionPressure Die-casting is similar to permanent vomit up casting except that the metal is injected into the mold below steep pressure of 7-350Mpa (1,000-50,000) psi. This high pressure will not be removed till the solidification is finished. It is called die-casting, because the molds in this casting operation are called dies. Metal is forced into the die cavity by the pressure is the most notable feature that shows this process is different from others in the casting category (Long et al., 2008).In this technique, the mould will not be destroyed after each cast but is permanent, being made of a metal such as cast iron or steel. There are two types of pressure die casting processes, lofty pressure die casting and low pressure casting. High pressure die casting is the most widely employ, representing about 50% of all light alloys casting production. Low pressure die casting before long accounts for about 20% of production and its use is increasing. Rests are gravity die casting, vacuum die casting and squeeze casting process (AZOM, 2008).Literature ch eck overHigh pressure die casting processIn high pressure die casting process, the liquid metal is injected at high reanimate and high pressure into a metal mould. A schematic view of high pressure die casting is given in Figure 1. above equipment contains two vertical platens on which bolsters are located which hold the die halves. One of the platen is fixed and the other can move to open and close the die. A measured amount of metal is poured into the shot sleeve and then introduced into the mould cavity using a hydraulically-driven piston. Once the metal has solidified, the die is opened and the casting removed (AZOM, 2008).For high pressure die casting process, special precaution must be considered to avoid too much gas inclusions which cause virulent during the subsequent heat treatment or wielding of the casting product. Since the casting machine and its dies are quite costly, only high-volume production will use the pressure die casting process for economical reason (AZOM, 2008).Low pressure die castingIn Figure 2, the die is filled from a pressurised crucible below. low-pressure die casting is especially suited to the production of components that are symmetric about an axis of rotation. Light automotive wheels are normally manufactured by this technique (AZOM, 2008).Benefits of the process developmentOver the last three years the biggest betterment of die casting process is the development of material property info and interfacial hear transfer coefficients. Material property thermal selective information is the essential part of any assumption program, which has been developed for various mold materials, provide system and metal alloys, such as aluminum, steel and compacted graphite iron. Furthermore, the work done to understand the smooth mechanics of filters is another development of the die casting process, which include the developed pressure drop data for pressed, extruded and reticulated foam filters and these data is easily available in the industry literature (ALLBUSINESS, 2008).There are types of the casting defects occur during production of pressure die casting process such as insufficient pouring, cooling separated, crack and shrink. They are formed in the mold filling and solidification processes, which contributed to the final casting performance. The processes of mold filling and solidification are developed in time sequence while the casting defects are forming, which can be reflected by its numeric simulation in order to predict the locations of the casting defects (Minaie and Voller, 1998).Numerical simulations of mold filling and solidification processes include numerical analysis, heat transfer, fluid mechanics, solidification theory, engineering mechanics, computer aid graph analysis etc. The mold filling process can be set forth very precisely and the reliable initial temperature field is provided for the next solidification process by using the advantage of numerical simulation on temperature and f luid fields, which benefits to elevate the simulation accuracy of solidification process. Numerical simulations of mold filling and solidification processes, which play the key function in the casting production, are the homo known leading area, widening and promoting the development of casting subject by using the advance computer applied science. And it also initiates a wise way to improve the casting quality (Baicheng and Houfa, 1998).Technical Challenges DetailsThe molten metal flux is the major issue that relates to the mold filling process, heat and mass transfer flow process at changeable temperature accompanied with heat loss and solidification. This process can be presented by the continuity and momentum equations. In addition, the energy poise equation can describe the heat exchange between the molten metal and the casting chamber. The consideration of position and movement of the free surface is the key for the calculation of unstable flow. Also, it is essential to deal with the boundary conditions of the free surface. There for, the mathematical equations can be expressed as follows 1, 2, 3, 4 and where is the density and u is the pep pillThe numerical simulation is a non-linear instantaneous thermal analysis in the solidification process. The casting form changes gradually with the decreasing of temperature from liquid state to semi-solid and solid states, in which many physical process and phenomenon played an important role for the casting quality take place, and the temperature field of the casting varies with the time. Therefore, the shrinkage cavity and slow down can be predicted with the numerical simulations of the filling and solidification processes (Laurent and Rigaunt, 1992).Range of ApplicationsCAD/CAM/CAE is now as an essential part to keep pace with growing technology and demand for quality, low cost, precision and faster delivery in tool engineering. The followings are the few latest methods, which are being used today in d ie making industryScanning of product to be die cast.CAD/CAM (Computer added design and manufacturing)CAPP (computer added process planning)CAI (computer added inspection)2D drawing to 3D modeling3D model to 2D drawingBlack-box designing (conceptual base designing)Analysis Simulation (stress, Strain, thermal analysis etc.)Analysis for Gate, runner, ejector pins and cooling line etc.NC data generationRapid prototypingConcurrent engineeringPressure die casting process is widely used in resource producing company, such as domain class Aluminum company Alcoa and NALCO, and copper alloy giant Kennecott.DrawbacksThe formation of blow-holes in the die casting is a major drawback, which is resulting from the turbulence produced by the high velocity when the liquid metal alloy is injected. Another major drawback is inevitable shrinkage of the casting as it solidifies, and which is proportional to the temperature at which the alloy is injected. Though flashy to make, the poor quality of cur rent die cast components therefore makes the use of finer quality alloys unfeasible (Moschini and Renzo, 1998).Recent finding Future directionIn the world of computer simulation time, the pressure die casting process improvements move very fast in the foundry industry today, a dress circle has changed in the last few years, for example, three years ago the computers that industry companies using to process the die casting process simulation were based on Unix workstations, which was more than $30,000 and the only way to analyze the filling of a mold cavity was using NavierStokes equations, which was extremely slow.Nowadays, the personal computer (PC) conversion is finished, some of new machines can run 20-30 times faster than the one in three years ago. For example, a very complicated filling and solidification work that used to run days and days can be completed in one hour (ALLBUSINESS, 2008).The concurrent development of optimization techniques have been capitalized on and inc orporate by the software companies into their programs. At first glance, this allows the user to let the computer serve well optimize such things as riser placement and size and gelidity locations. However it isnt hard to imagine that this is just the beginning, and that we are about to get on a journey in which die casting process simulation programs soon will perform what is unthinkable today (ALLBUSINESS, 2008).ConclusionDie casting molds tend to be expensive as they are made from fixed steel-also the cycle time for building these tend to be long. Also the stronger and harder metals such as iron and steel cannot be die-cast in the past. However, by the develop of the numerical simulations system and optimization techniques, these issues are no longer impede the pace of progress in the modern world. Numerical simulations and optimization techniques can help foster the success and viability of the foundry industry for many years to come. The more capability and accuracy that is built into our simulation tools, the better and more efficient casting can be produced.ReferenceALLBUSINESS 2008, Solidifying castings future process simulation software round-up, http//www.allbusiness.com/manufacturing/fabricated-metal-product-manufacturing/244509-1.html Accessed 2 May 2008AZOM 2008, Aluminium Casting Techniques Sand Casting and Die Casting Processes, http//www.azom.com/work/gmQ9Dmtd0mw9jnoTHN6z_files/image008.gifimgrefurl Accessed 2 May 2008B. Minaie and V.R. Voller, Comprehensive numerical models for die casting process, Model. Cast. Weld. Processes IV (1998), pp. 513-525.J, M. Long, N. Deshpande, C. Ferguson, M. Kwok and H. Briggs, Materials and Design Module 2 Introduction to Manufacturing Processes, Deakin University. 2008, pp. 229-230.L. Baicheng and S. Houfa, Progress in numerical simulation of solidification process of shaped casting, J. Mater. Sci. Techol. 11 (1995) (5), pp. 312-324.Moschini and Renzo 1998, Die casting process for producing high mechanic al performance components via injection of a liquid metal alloy, http//www.freepatentsonline.com/EP0513523.html Accessed 2 May 2008S.M. Xiong, F. Lau and W.B. Lee, Numerical methods to improve the computational efficiency of thermal analysis for the die casting process, J. Mater. Process Technol. 1-3 (2003), pp. 457-461.S.P.SHARMA 2008, Upgraded Technology and Application in Die Casting, http//www.creativecadcam.net/die-casting.pdf Accessed 2 May 2008V. Laurent and C. Rigaut, Experimental and numerical study of criteries functions for predicting microporosity in cast aluminum alloys, AFS Trans. 100 (1992), pp. 647-655.