Aluminum Die Castings
One type of metal casting that is heavily used today is aluminum die casting, an efficient and economical casting process that produces widely applicable shapes and products. While aluminum die casting has the potential to be more energy intensive than other metal die casting processes, many manufacturers still choose to engage in the process because of the many benefits it presents.
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History of Metal Casting
Humans have been casting metal for over four millennia. Made of copper, the earliest discovered metal casting is believed to have been created around 3200 BCE. Meanwhile, it appears that the use of iron metal castings originated circa 800 BCE, followed quickly by sand castings in the sixth century BCE. With such a long history together, it is no wonder that metal castings have become such an integral part of the modern world’s commerce and industry. Castings of all kinds, including aluminum die casting, play an important role in untold numbers of industrial, commercial, and consumer processes and contexts.
Applications of Aluminum Die Casting
Among the many industries that take advantage of the assets of aluminum castings are automotive, construction, hardware, marine, aerospace, and plumbing. Their heat resistance and dimensional stability, for instance, make them the perfect match for cast valve covers in vehicles. They work so well in the production of hardware and tools because of their superior resistance to corrosion and high temperatures.
Benefits of Using Aluminum Die Casting
Made from aluminum alloys, aluminum die castings are favored for their light weight, high corrosion resistance, strength at high temperatures, electrical and thermal conductivity, and excellent mechanical properties. In addition, aluminum alloys enjoy a high dimensional stability, even when formed into complicated shapes with thin walls. Thanks to these notable attributes, aluminum die castings can be ordered in a wide variety of durable components and shapes.
Materials Used in Aluminum Die Casting
Some of the most common aluminum alloys used for industrial and commercial applications include duralumin (aluminum and copper), Al-Li (aluminum and lithium), silumin (aluminum and silicon), magnox (aluminum and magnesium oxide), and 2011 aluminum (a combination of seven elements). Alloy choice depends on the needs and environment of the setting. Magnesium alloys, for example, tolerate anodizing treatments well and are therefore well-suited to the casting of decorative pieces and architectural elements. Al-Li is a great example of an extremely lightweight alloy. Because it is so light, it lends itself extremely well to aerospace applications.
Process of Aluminum Die Casting
While countless years have gone by and many technological advances have taken place since the inception of casting, the basic metal casting process and the operating principles behind it remain the same. Simply put, metal casting involves melting a metal and forcing it into a mold in order to give it a shape. The process of aluminum die casting takes place in a cold chamber die caster to accommodate aluminum’s high melting point. It starts with the collection of raw aluminum material, gathered in a reservoir. While it resides in the reservoir, the raw aluminum metal is heated and pressurized until it eventually becomes molten.
Once it is molten, the aluminum is forced or injected into a mold cavity, or die, that, as the metal fills it and forms around its contours, gives the aluminum its intended shape. After the molten aluminum has taken on the shape of the mold, it is permitted to cool and re-harden. Once it is hard and cool enough to move, the new aluminum shape is ejected from the mold and labeled as a cast aluminum product.
After a cast aluminum product is ejected from its mold, a manufacturer has a few choices. He or she may choose to prepare it for shipment to customers or send it on for additional processing. Frequently, additional processing proves unnecessary, thanks to the close tolerances of most aluminum die castings. However, secondary processes and machining are sometimes needed. In this case, aluminum die castings may undergo finishing, deburring, polishing, or plating.
Finishing may refer to any number of processes, such as heat treatment, as well as efforts to color or alter the casting surface in any way. Deburring is the process by which burrs, which are unsightly bumps, and other imperfections are smoothed, ground, or vibrated away. Polishing, of course, is the process of eliminating smudges and creating shine. Plating, on the other hand, is the manufacturing process by which a substrate receives a thin coating of metal. This may be accomplished through electroplating, wherein an electrical current reduces a conductive metal layer, like copper is reduced onto the aluminum, or through electroless plating. Electroless plating, also called chemical or autocatalytic plating, does not use electrical power, instead inducing plating through several simultaneous solutions in an aqueous solution.
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