The die casting process involves injecting molten metal with low melting points such as zinc and aluminum into the die casting mold and allowing it to cool. Depending on the melting point, it occurs under two different mechanisms (hot and cold chamber casting), and it is suitable for making simple and complex sheet metal parts.
Die Casting Alloys
Most alloys used in die casting are non-ferrous with strong mechanical properties. The non-ferrous moiety is responsible for the low melting point in agreement with the strong mechanical properties. The type of properties needed depends on the material being worked on. Consequently, there is no limitation when choosing a material. However, below are the several popular alloys:
· Aluminum alloy die casting
Aluminum alloys have unique properties, making them applicable in making a wide range of products. On the one hand, the aluminum alloy 380.0 is the most common material in die casting due to its unique properties. Other alloys include Aluminum Alloys 360, 390 and 413. You can use aluminum alloys because of the following:
· Zinc alloy die casting
Zinc alloys have incredible strength, toughness, firmness, performance and cost-effectiveness. As a result, they are an important part of the die casting process, with properties rivalling and exceeding other alloys such as aluminum, magnesium, and bronze.
There are many alloys of zinc you can use. However, the common die casting zinc materials are Zamak #2, #3, #5, #7, ZA8 and ZA27, known for the following properties:
· Magnesium die casting
Magnesium is another material used for die casting. It has many alloys, but the most common one is the AZ91D, known for its toughness, durability, lightweight and good castability. It is 75% lighter than steel and 33% lighter than aluminum without a loss in strength. Most enthusiasts prefer magnesium as it is better for complex casting with tight tolerances and it has better corrosion resistance.
· Other Alloys
Other alloys suitable for making die casting parts include Bronze, Brass, lead and tin.
Tin is the first material used in die casting due to its high fluidity. It has a low melting point, and it leaves little or no wear on the molds.
Bronze (white bronze) is the right die cast material used in the jewelry industry. It has a similar color to white gold and stainless steel alloys but is suitable for die casting due to its low melting point.
Surface Finish Options for pressure die casting parts
The diecast must have a good surface finish that will promote durability, protection, or aesthetic effect. There are different finishing options you can use for die casting parts. However, choices are based on the size of the cast parts and the alloy you are using.
Painting is the most common surface finishing technique ideal for many materials. It can be for further protection or aesthetic purpose.
The process involves applying lacquers, paints, or enamel with special consideration for the metal used. Before the addition, clean the surface of the metal to remove impurities such as oil (this also helps in adhesion), add an underlying paint (primer), and the primary paint.
Powder coating is another common decorative finish you can use for your die casting part. It involves applying charged particles on the surface of the die casting part. This process is ideal as it hides minor flaws on the die cast surface, has better thickness control and is uniform. Consequently, the product becomes durable, hard, high anti-corrosion and anti-scratch on completing the process. Powder coating is environmentally friendly as it produces no hazardous toxic material
This surface finish technique gives the cast an antique look, and it is mostly applicable to zinc casting. The casting is electroplated with copper or other alloys and then covered with a colored component such as copper sulfide. The casting is relieved (i.e., removing some colored layers to give the underlying later of copper) and then treated to prevent tarnishing.
Ceramic coating is a decorative process and involves adding ceramic in its solution form to the exterior of a part. The process produces a thin layer that is similar to anodizing. Consequently, surface preparation procedures are important before their applications.
Plating can be electroless or electroplating processes and is a suitable and cheap method for die cast finishing. As the ceramic coating option, the layer of finish is thin. Therefore, you need a surface preparation procedure before using it.
Electroless plating uses chemicals instead of electricity to plate a diecast part. The die casted part is placed in a chemical with reducing properties. When catalyzed by other minerals, the chemical becomes deposited on the die cast. Electroplating is similar. However, instead of being catalyzed by minerals, the catalysis occurs by passing a current through the electrolyte. Both methods are ideal for aesthetic purposes. Although some sheet metal enthusiasts use it to improve some parts’ conductivity.