Die Casting vs Sand Casting: Surface Finishes
The average consumer is not likely to be familiar with the intricacies of die casting and sand casting, the primary industrial casting techniques. Die casting and sand casting are two techniques of manufacturing metal parts by forcing molten metal into a pre-made mold under pressure. Each of these two techniques result in two different types of surface finish that an expert would examine and take into account when considering which process to use for a specific project. In this article we will discuss the differences between die casting and sand casting surface finish.
Die casting is the more complex of the two processes, and as such it produces a superior surface finish. The pre-made mold is machined out of a steel die, wherein the molten metal is forced into the die to take on the shape of the mold. As the molten metal is poured in to the die and cooled, it is smoothed out and polished. The result is a finished part that has a glossy and uniform surface finish. Due to the high-pressure process applied in die casting, the internal structure of the part is also stronger and more resistant to impact and wear.
On the other hand, sand casting is a simpler and more adjustable process that produces a great degree of surface finish variation. In sand casting, a mold is made by packing sand around a piece of metal, wax, or plastic. The molten metal is then poured in to the mold and allowed to cool. As the metal cools and solidifies it takes on the shape of the mold. However, since the mold is made out of sand, the surface finish of the finished part has more texture and is usually not as uniform as that of a die cast part. The surface finish of a sand cast part can range from a rough and uneven surface finish to a smooth and glossy surface. The rough surface may result from sand grains becoming embedded in the surface, but it can also be improved by machining the part and polishing it.
The surface finish of a part manufactured through die casting or sand casting can have a significant impact on the part’s function and aesthetic. Die casting produces the best surface finish but is more expensive and time consuming than sand casting. On the other hand, sand casting produces a wide range of surface finishes and is much cheaper and faster than die casting. Depending on the requirements and budget, an experienced engineer can choose which process to use in order to produce a part with the desired surface finish.
