A high production rate and cost-effective method used primarily in the production of nonferrous metals is die casting (PDC) technology. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get Original EssayIt is widely used in the production of automotive components of complex geometry and complex shapes and forms which can be difficult with other conventional manufacturing processes. The document provides an overview of the types of die casting techniques. It also describes recent trends and developments made in die casting technology. Numerical simulation is one of the cost-effective methods used for the optimization of the casting process. The various simulation methods available for numerical simulation of castings are discussed. The document also describes the use of the integrated CAD/CAE approach and the parametric design approach which simplifies the design process. The study carried out in the paper also discusses the importance of residual stresses and their effects on the fatigue life of cast components. The most important tool in the die casting operation is the "mold", which consists of the mold cavity into which molten metal is forced under pressure so that the required component is cast. The causes of the failure and the possibilities for repairing the molds were discussed. Keywords - Die casting, Numerical simulation, Software simulation, Residual stresses, Die failureThe die casting process is characterized by forcing molten metal at high speed and high pressure through a complex system of gates and channels into the tool die cavity called ' die' [1]. The cavity in the mold has the shape to be formed. The process has the ability to produce complex shapes with good dimensional accuracy, surface finish and high material yield. It is widely suitable for casting non-ferrous metals such as Zn, Cu, Al, Mg, Pb and Sn based alloys. Depending on the pressures used, the die casting process can be of two types: mainly high pressure die casting (HPDC) or low pressure die casting (LPDC). Depending on the injection mechanism used, HPDC is classified as a hot-chamber HPDC process and a cold-chamber HPDC process. In the hot chamber process, the injection mechanism is placed inside the metal furnace where the components are in constant contact with the molten metal. It ensures minimal contact of the metal with the air thus reducing the possibility of gas trapping defects but reduces the life of the components. In the Cold Chamber process, however, the injection system is kept outside the furnace and the metal is poured manually/automatically through a ladle. Increases component life but increases the chance of gas trapping defects [2]. Nearly 70% of aluminum components produced today use HPDC [3]. HPDC is widely used in the automotive and communications industries to form high-quality, thin-walled, complex-shaped, low-cost cast components [4]. Numerous parameters such as product geometric design, raceway system design, mold and metal temperatures, flow velocity, flow pattern, heat flow, and solidification rate have been found to affect the quality of die castings [5]. One of the main challenges when designing a mold is determining whether or not the final part has defects. There are numerous software packages available such as MAGMA, PROCAST and FLOW 3D, FLUENT, etc. for process simulationof fusion. They help in optimizing design parameters and enable designers to quickly and accurately identify and locate defects which enable parts to be produced with higher quality in a shorter period of time [6]. The optimal design of the casting system and mold geometry is crucial for the homogeneous filling of the molds which closely influences the final quality of the cast components. The quality of castings produced by the pressure mold casting process mainly depends on the filling pattern of the channel and gate system used. A homogeneous mold filling pattern ensures good quality castings. Furthermore, despite the design of the sliding door system, their correct position and size plays a very important role in controlling defects such as porosity and cracks. Inadequate casting system design usually results in the production of castings with defects such as gas and shrinkage porosity, blowholes, cold shuts, incomplete filling, flow lines, and poor surface finish [7]. These casting defects have been shown to affect the static and fatigue strength of cast alloys, which limits the use of cast parts in critical high-strength applications [8]. Parameters such as filling pattern, pressure, filling rate, cooling rate and solidification largely influence the formation of defects in castings. The most frequently encountered defect in castings is porosity, which is closely related to the casting process parameters and has a serious impact on the cost of the casting process due to waste loss [9]. The mold filling process is a typical two-phase liquid-gas phenomenon. The interaction of molten metal and gas in complex molds plays an important role in the formation of gas-trapping defects. Numerical simulation tools can help in the quantitative prediction of such defects [10]. It also allows you to visualize the progressive cooling from inside the casting towards the external environment. Helps understand changes that can be made to design parameters to achieve a consistent mold filling pattern and optimize the design. The high filling speed, high temperature of the liquid metal, opacity of the metal mold and high metal pressure create difficulties in direct visual evaluation of the mold filling process. Therefore designing and modifying the sliding door system using numerical simulation depends on the trial and error approach.B. Simulation Methods Available for Numerical Simulation of Die Casting Numerous methods and software packages are available for simulating and analyzing the die casting filling process. Software packages are generally grid-based and use the volume of fluid (VOF) method to track free surfaces [1]. Methods such as finite difference method (FDM), finite volume method (FVM), finite element method (FEM), lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH) are used to solve the fluid flow equations that govern the mold filling process. Among the Eulerian techniques are the Mark and Cell (MAC) method, the level set method, the Volume of Fluid (VOF) method and the arbitrary Lagrangian Euler method which are used to study free surface flows [10]In the Marker and Cell (MAC) method, Lagrangian markers are placed on the interface at the initial time. As the interface shifts and deforms, markers are added, deleted, and reattached according toneed. The surface evolution between different fluids is traced by the movement of markers in the velocity field. It is difficult to maintain mass conservation and determine good interpolation of the surface in three dimensions. However, this technique does not suffer from numerical diffusion and provides accurate results in two dimensions. In the Volume of Fluid (VOF) method, the volume of fluid in each computational cell is represented using a color function. The use of color features to represent interfaces makes them prone to suffer from numerical diffusion and numerical oscillations. According to the advection equations, the volume fractions are updated and the free surfaces of the fluid with fractional volume should be reconstructed for each time step. This type of reconstruction is difficult in three dimensions but, due to the relative ease of implementation and its basis in volume fractions, this method is suitable for incorporating other physics and is the most popular and widely used method [11].SPH is a Lagrangian method that does not need a grid calculates its spatial derivatives and uses a compact support interpolation kernel to represent any field quantity in terms of values ​​in a set of disordered points which are particles. The computational structure on which fluid equations are solved are the flow particles. Particle information allows the calculation of smooth approximations of the physical properties of the fluid and provides a way to find gradients of fluid properties. This method is applicable to multidimensional problems and is particularly suitable for complex fluid flows due to its Lagrangian nature. Fine details such as plume shape, oscillation frequency and phase, and correct relative heights of all free surfaces can be captured using SPH.C. Software tools available for numerical simulation Numerical simulation results can be validated using analog water experiments or software simulations. There are various commercial CAE software packages available that facilitate the simulation and analysis of flow processes. With rapid advances in computer technology, different types of finite element software, including both professional casting software and general analysis software, are coming into use in practice around the world. Integration of die casting CAD/CAE system and semi-automatic parametric design of casting system With the increasing competitiveness and increase in demand from the market, a strong impact is exerted on designers to reduce casting defects and improve the quality, rate of production and the life of the moulds. Depending on characteristics such as the type of die casting machine, casting geometry and alloy properties, mold designers can determine the location, shape and dimensions of a mold's slide system using appropriate CAD packages such as Unigraphics , CREO Parametric, Catia, etc. By integrating the CAE package with CAD, parameters such as optimal injection pressure, injection speed, filling time, defects related to casting filling and solidification process etc. can be achieved. [12]. Recent advances have incorporated the parametric design approach into various CAD/CAE systems. In the parametric design approach, variable dimensions are treated as control parameters that allow the designer to modify the existing design simply by changing the parameter values. This approach facilitates the efficient design of part families whose members differ only in size, reducing the work of repeatedly creating parts fromzero because a single parameterized model can be developed to represent a family of parts. In parametric design, a gating model database (or feature library) is already built that includes the original parametric gating models built using a 3D CAD tool. These models can be easily retrieved from the database, modified with certain specified parameters and positions, and then connected to the die cast part. The parametric design approach therefore serves to reduce time and make project updating simpler and faster [13].E. Residual stresses in casting and their effects on fatigue and fracture. Heating is unavoidable in the die casting process and temperature differences in the casting together with other loading conditions lead to the formation of residual stresses. These are the stresses that remain in the casting after expulsion from the mold cavity. The formation of residual stresses in the casting is associated with causes such as temperature gradients due to continuous heating and cooling of the casting, prevention of contraction by the mold, and rapid solidification of the mold [14]. Residual stresses, if present in the cast component, significantly reduce its fatigue life and cause shape changes and cracks in the castings. However, they can have a life-enhancing (positive) or life-reducing (negative) effect that depends on the sign of the residual stress versus that of the applied stress. Tensile residual stresses are the most dangerous since in service they lead to the formation of fatigue crack initiation and growth [15]. During the cold phase of the die casting cycle, these tensile stresses appear on the surface and lead to local plastic deformation on the mold resulting in crack nucleation and growth [16]. Residual stress measurement can be performed experimentally or often with a combination of simulations using advanced numerical analysis techniques. Optimal mold design together with proper machining and heat treatments could keep residual stresses minimal [17]. Some of the most common methods for measuring residual stresses are X-ray diffraction, drilling, and sectioning methods. X-ray diffraction and hole punching methods are non-destructive but are sensitive to microstructure and geometry. However, sectioning is a very suitable destructive method for measuring macrostresses in components. Knowledge of residual stresses is important to analyze their influence on fatigue and fracture performance in order to combat failure. Different types of tool steels with/without surface treatment are used to produce molds. The life of dies and molds in industries is improved with timely repair of damaged surfaces. The extent and severity of damage depends on the required precision in the shape and size of the molds and the operating conditions of the tool. The life of the mold with a given geometry, material and heat treatment largely depends on the die casting parameters. The hot phase of the cycle produces high compressive stresses which usually retard crack nucleation and growth, but are a major cause of local plastic deformation. Filling pressure also increases compressive stresses in the molds. Different types of stresses are produced in the mold during operation, and molds fail when the stress value becomes greater than the strength of the tool steel. The mold surface is rapidly heated by injecting molten metal and 34 (2013) 519-535