Die Casting vs. Sand Casting – What’s the Difference?
Casting metal is an ancient process that now can be accomplished in a number of ways. It involves pouring molten metal into a mold where, upon cooling, the metal solidifies and conforms to the mold’s shape. Casting allows manufacturers to create complex parts without the need for machining, which can be time-consuming and complicated; however, it is far from a simple, cut-and-dry technique in today’s industry. There are many types of casting processes used in modern manufacturing, and each has its distinct benefits and disadvantages depending upon the desired characteristics of the end product. To better understand these unique processes, this article will explore two of the most widely used casting procedures: die casting and sand casting (to learn about other casting methods, read our article on the types of casting processes). A comparison of these two casting methods will give manufacturers a better idea of when to implement each process, and which one of these popular methods is best suited towards their application. This article will first explore each process, and then compare them to display why certain manufacturers choose one over the other.
What is Die Casting?
Die casting is a highly-detailed casting process where reusable metal molds – known as “dies”- are filled with liquid metal under pressure to create tight-tolerance, highly accurate parts. The dies are usually made by machining two mold halves out of a tool steel into the desired exterior contour of a part, and they last between 15,000-500,000 castings per die. They are a large capital investment as they are difficult to machine and test, so it is important for companies to ensure their dies are correct. They are also technically complex, containing water-cooled channels, runners, sprue holes, guide pins, cores, ejector pins, and other high-level accessories that help facilitate a quality casting. These features also allow the die casting process to be more readily automated, and die casting is particularly useful when mechanized in such a way. A lubricant must be sprayed onto each die half before casting begins (known as a “releasing agent”) which will allow the final part to be easily removed from the mold, and protects the mold from damage. A casting metal (often aluminum or steel) is then forced in the clamped die halves under high pressure, where the metal will conform to the die’s shape. Die casting machines come in both hot and cold chambered machines, which differ fundamentally based on the injection method of the molten metal, as well as the types of metals used in each machine. The quality of die-casted parts are exceptional both in dimensional accuracy and surface finish, making this process most useful for medium-sized parts with complex details such as automobiles, gears, appliance parts, toys, and much more.
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