Investment casting (known as lost-wax casting in art) is a process that has been practiced for thousands of years, with the lost-wax process being one of the oldest known metal forming techniques. Sand can be recycled many times in most operations and requires little maintenance. The sand is bonded using clays, chemical binders, or polymerized oils (such as motor oil). Green (moist) sand, which is black in color, has almost no part weight limit, whereas dry sand has a practical part mass limit of 2,300–2,700 kg (5,100–6,000 lb). Sand casting requires a lead time of days, or even weeks sometimes, for production at high output rates (1–20 pieces/hr-mold) and is unsurpassed for large-part production. Sand casting also allows most metals to be cast depending on the type of sand used for the molds. The process allows for castings small enough fit in the palm of one's hand to those large enough for a train car bed (one casting can create the entire bed for one rail car). Not only does this method allow manufacturers to create products at a low cost, but there are other benefits to sand casting, such as very small-size operations. Sand casting allows for smaller batches than permanent mold casting and at a very reasonable cost. Sand casting is one of the most popular and simplest types of casting, and has been used for centuries. This method of mold casting involves the use of temporary, non-reusable molds. Įxpendable mold casting is a generic classification that includes sand, plastic, shell, plaster, and investment (lost-wax technique) moldings. It is further broken down by the mold material, such as sand or metal, and pouring method, such as gravity, vacuum, or low pressure. The modern casting process is subdivided into two main categories: expendable and non-expendable casting. Traditional techniques include lost-wax casting (which may be further divided into centrifugal casting, and vacuum assist direct pour casting), plaster mold casting and sand casting. Highly engineered castings are found in 90 percent of durable goods, including cars, trucks, aerospace, trains, mining and construction equipment, oil wells, appliances, pipes, hydrants, wind turbines, nuclear plants, medical devices, defense products, toys, and more. Ĭasting processes have been known for thousands of years, and have been widely used for sculpture (especially in bronze), jewelry in precious metals, and weapons and tools. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods. The metal and mold are then cooled, and the metal part (the casting) is extracted. The metal is poured into the mold through a hollow channel called a sprue. In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold (usually by a crucible) that contains a negative impression (i.e., a three-dimensional negative image) of the intended shape.

Weight limit on metal plaster ring