![]() Very smooth metal surfaces are usually created with machining, which is an extra cost: if shiny and smooth is a desired outcome, choosing a casting method with a finer finish may reduce machining costs. How granular, bumpy, or rough can the surface of the casting be? What is acceptable for a cast iron pan is not acceptable for a wedding ring. Surface finishingĪnother consideration is surface finishing. This means that the product is very close to being the right size when it is shaken out of the mold. If a product needs to be precise, a client may want a casting method that produces near net casting. Metal shrinks when cooling, and the type of casting influences by how much. Dimensional tolerance is the variation acceptable in the size of the final product. One of the important factors in choosing a casting method is dimensional tolerance. These are usually made of the same metal as the final casting as they sit in the space that will flood with material and become part of the final casting. If the core is very long, it might be supported by chaplets to prop it up. The empty spaces around the core will fill with metal, and the core will be removed from the final casting, leaving a hole where it once was. The cores are usually held in place by extending past the casting and being held in place through core prints, which suspends the core like a bridge between two banks. These cores are shaped like the internal space. If a mold is supposed to have internal spaces or holes, a core is often made. ![]() In vertical molding, the leading half of the mold is called the swing, and the back half is called the ram. ![]() In horizontal molding, the top half of the mold is called the cope, and the bottom half is called the drag. These molds can be made with a horizontal split Cope and drag By making the mold in two parts, the pattern can be withdrawn before filling. Half of the pattern is imprinted on one side of the mold and half on the other, and then the halves are clamped together before the mold is filled. Most molds are for more complex shapes and are based on a pattern. The forms used to create ingots of metal are like loaf pans, with the metal simply poured inside and left to cool. Casting terminology Casting moldĪ mold is a cavity in a material that receives liquid metal and produces a cooled object in the shape of that cavity. What type of casting is most efficient depends on the metals used, the size of the run, and the complexity of the casting.īefore starting a production run, it is helpful to know some of the terms and methods from the foundry floor.Ĭope and drag, or ram and swing, are words for the moving and stationary parts of a green sand mold. There are many metal casting methods to choose from. Casting is often a less expensive way to manufacture a piece compared with machining the part out of a piece of solid metal. The metal then cools and hardens into the form given to it by this shaped mold. Metal casting is the process of making objects by pouring molten metal into an empty shaped space.
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