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The contours and properties of a die cast part are determined by the mold. This article explains the fundamental principles of how the melt can be shaped.
Basic Knowledge of Die Casting Tools and Molds 
Die casting is a forming process used in the mass production of parts made of aluminum, magnesium, and their alloys. Die casting machines, which are divided into hot chamber and cold chamber die casting machines, are used for the casting process. The primary difference is that in hot chamber casting machines, the container containing the molten metal is located within the machine, whereas in cold chamber casting machines, the container is located outside of the machine. In both types of machines, the molten metal is pressed from a casting chamber through one or more casting channels into the cavity of a permanent steel mold, where it takes on the shape determined by the die and solidifies. Die casting molds are divided into two halves in order to allow for the removal of the cast part from the mold. The feed side mold half is mounted on a fixed plate on the rigid side of the die casting machine, while the ejector side mold half is mounted on a movable plate on the other side. Before closing, the halves are sprayed with a release agent to ensure that the cast part can be easily removed from the die casting mold [diecasting-mould.com] and that the plates do not overheat. Depending on the size of the cast parts, up to 300 casting cycles per hour can be completed.
Extreme Loads
When the mold is closed, the melt is forced into the mold under a pressure of up to 1,200 bar, resulting in maximum mold filling speeds of 150 m/s (540 km/h). High closing and clamping forces are required to press the mold halves against each other and keep the molds closed: up to 8,000 kN (800 t) in hot chamber die casting machines and up to 45,000 kN (4,500 t) in cold chamber die casting machines. Large-scale cast parts can be produced using such high forces. In terms of material and design, the molds that are used for this purpose must be constructed in such a way that they can withstand the loads associated with large melt quantities indefinitely. When the metal has solidified, the die casting mold is split in half, and the cast part is ejected by bolts or removed by a robot and conveyed to a subsequent processing station.
High-Performance Steels
Molding is a critical aspect of the die casting services [diecasting-mould.com]. It determines the contours that must be transferred to the cast part, and it should also allow the cast part to solidify as quickly as possible. In this way, the formation of a fine-grained microstructure is encouraged, which is beneficial to the casting quality. In order to achieve optimal cooling, the molds are cooled in specific areas. Another advantage is that the production time is reduced, which results in cost savings. The design of die casting tools is described in detail in the DIN 16760-1 standard. The tools used in the die casting process are invariably subjected to high thermal and mechanical loads, and they must be able to withstand these stresses indefinitely. Molds for zinc die casting, for example, can be used for 500,000 to 2 million cycles before needing to be replaced. In order to achieve such results, the die casting tools, which in addition to the above-mentioned molds include mold inserts, cores, slides, and ejectors, are made of high-strength hot-work steels such as X40CrMoV5-1 (1.2344) or special materials such as hard metals. High wear resistance, high ductility, high heat resistance, high hot tearing and hot wear resistance, as well as good thermal conductivity, are all characteristics that are critical in the design of these tools. When selecting materials, it is necessary to consider their technological properties, the design of the tools, the heat treatment of the tools, and, last but not least, the complex interactions between the tools and the metal to be cast. 
The use of CAD/CAM systems
In the past, die casting tools were manufactured on the basis of drawings; today, designers work with 3D CAD data and cutting-edge information technology. Casting molds must take into account both the casting process – and thus the melt flow and cooling – as well as the geometrical and geometrical dimensions of the die cast parts that will be manufactured. The cast parts should have a uniform, fine-grained microstructure, high dimensional accuracy and dimensional stability, and excellent surface quality. Computer-aided simulation calculations aid in the design of tools that are optimally suited to die cast parts. CAM systems are used by toolmakers and moldmakers to manufacture their products. CNC controlled milling machines, as well as die sinking and cut erosion machines, are used to incorporate the forming contours into the molding material with high precision. Mold production is a time-consuming and expensive endeavor due to the complexity of the molds' construction.
The cost of tooling can account for up to 20% of the total cost of an aluminum die cast part. However, for the production of components in large series, this is more cost-effective from a certain lot size onwards than manufacturing the parts in other ways, such as through machining processes. In addition, the manufacturing time for each part is reduced. The Institute of Machine Design at the University of Magdeburg, Germany, has developed a standardized, time-saving procedure for the design of die casting tools.
The design diversity of die cast parts, as well as the demands placed on them, are constantly expanding. As a result, the demands on the properties of tool steels used in die casting, as well as the structural design of the tools and molds made from these steels, are increasing as well. These steels, as well as the software programs that will be used for design and simulation, as well as the capability of the machining systems, are all constantly evolving. The topics of digitization (Industry 4.0) and 3D printing are becoming increasingly important. Trade fairs are adapting to this new trend. In conjunction with the special show „Additive Manufacturing“, the EUROGUSS pays particular attention to this topic. Processes can be controlled more efficiently and the potential for optimization can be more easily identified when digital technologies are used.
With 3D printing processes, it is possible to create parts that are not possible to manufacture using conventional processes, such as inserts for die casting molds with a complex shape and integrated cooling channels that are close to the contour and curved. As Dr.-Ing. Ioannidis, President and CEO of the die casting machine manufacturer Oskar Frech, Chairman of the Foundry Machinery Association, and Member of the Board of the Additive Manufacturing Association in the German Machinery and Plant Manufacturers Association VDMA, believes that there is still a great deal of potential for mold making in this area:The overall heat management in the mold can be influenced in such a way that, for example, the mold is better protected against wear and the quality of the part to be cast can be influenced.