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Die casting (also called pressure die casting ) is a commonly used manufacturing process that involves pouring molten metal under high pressure and high velocity into a mold cavity. Die casting has a variety of applications, but is most commonly used for non-ferrous metals, especially when the geometries involved are complex and the production volumes are large. Some metals that are most frequently used in the case of die-casting are Aluminum, Zinc, Magnesium and Brass.

Due to the usage of ferrous materials for die making, the types of materials that can be used for casting are much more constrained when compared to other standard casting processes. For instance, many high melting point materials such as Iron (with melting point 1538° C ) and other ferrous materials cannot be used for manufacturing via die casting (although recent research has experimented with ferrous material die casting ). Besides the choice of materials, several other requirements of die casting such as the design of section changes, combination of product functions and design of a suitable ejector mechanism become important when considering the long term investment in dies. As a result, die casting is extremely relevant and germane for rule based DFM analysis.

Advantages and Disadvantages of Die Casting
There are many advantages of employing die casting over other types of casting processes:
 * 1) Die casting is suitable for mass production due to high production rates achievable, as well as the uniformity of parts manufactured via die casting.
 * 2) Due to the good surface finish and high dimensional tolerances seen in die casting, minimal post-processing is generally required.
 * 3) Parts with a much higher complexity can be created, along with parts that have much thinner wall sections.

Besides the advantages, there are certain disadvantages to using die-caring as well. For instance, die casting is prone to certain types of defects, such as micro-porosity, especially due to the faster solidification rate, presence of die lubricants and trapped air bubbles. Furthermore, the utilization of high pressure often constrains the type of geometries that can be cast. For example, it is often difficult to cast hollow shapes, as they cannot sustain the high pressures, along with the temperature constrains that are imposed on the dies. Additionally, the high cost of manufacturing dies is often prohibitive.

Material Considerations
While using die casting, an extremely important consideration for design is the material considerations. Compared to other, more traditional forms of casting (for example sand casting), there are far more limitations on the type of materials that can be used. Mostly, non-ferrous metals are used for die-casting, primarily because of their lower melting points. Zinc alloys, having a melting point somewhere between 370° C and 430° C, are commonly used in die casting, and respond fairly well to the die molding process. Brass and Bronze alloys can be die cast just as easily as Zinc alloys. Along with these alloys, Aluminum, Tin and Lead are also frequently die cast. Both Tin and Lead are used where corrosion resistant properties are required, although Lead can't be used for manufacturing food-grade containers. . Additionally, dies can only be made of refactory materials, with a melting point greater than 1700° Celsius.

Recently however, there has been new research into the use of ferrous materials in die casting. Although ferrous material die casting may be viable in the future, presently, it should not be considering during the DFM analysis stage.

General Design Considerations
Once an appropriate raw material has been selected for being manufactured via die casting, the next important design considerations for designing the die and the part component are listed below.

Combining Functions
As mentioned earlier, the fixed cost of manufacturing the die often plays an extremely important role while determining the overall cost of manufacturing via die casting. As a result, it is vital to design a die that incorporates the maximum number of features of the design geometry into the casting process. By employing this strategy of combining into a single process of die casting many functions of the part that would have otherwise required separate machining steps, the pay-off of the investment into manufacturing the fixed dies is greatly enhanced.

Designing Dies vs. Designing Product
As a general practice, the workpiece (i.e. the finished cast product) should be designed prior to the design of the appropriate die. This is because most parameters of the dies will be decided based on the design geometries of the workpiece. Furthermore, the material of the die will depend on the melting point of the material of the casting. For example, the material considerations of the die are going to be different in the case of the cast metal being Aluminum (melting point 660° C ) versus the cast metal being Lead (with a melting point of 327° C ).

Designing Ejector Pins
Ejector pins are an extremely important component of any casting, but because of the stasis nature of dies in die casting, the location of ejector pins becomes even more important in the case of die casting. As a result, the design of ejector pins should be planned out a early as possible during DFM analysis. In fact, it is advisable to plan for designing the ejector pin locations during the design of the of the product itself. For instance, if the imprints left by ejector pins can not be machined away, in that case alternative ejection mechanisms must be sought.

Avoiding Abrupt Sections
While a lot of casting defects are avoided in die casting due to the high pressure and high velocity with which the molten metal is injected into die cavities, it is still advisable to avoid abrupt changes in the geometry of the part. For instance, sharp corners, walls at acute angles to each other, and steep radii changes should all be avoided for easier metal flow and lesser occurrences of blowholes, cavities and other surface casting defects.

Dimensional Tolerances in Die Casting
When compared to sand casting and gravity die casting, high pressure die casting can be used to achieve good dimensional tolerances for products, which is useful for eliminating additional finishing steps after casting. However, there still persist dimensional variations in die casting as well. These are primarily due to thermal expansion of the die, along with the more typical expansion of the casting. In general practice, it is common to take a shrink factor of 0.6% for dies as a design consideration, for both expansion as well as contraction of dies during casting.