Casting & Forging Tool Manufacturing
Casting and forging are two different methods of metal manufacturing. Both processes have been going on for thousands of years, but what are the differences between the two methods of metalworking?
What is Casting?
Casting is the process of casting molten metal into a mold or die and allowing it to cool and harden so that it takes the shape of a mold. The process is ideal for mass production of parts with the reuse of identical molds to make identical products.
There are many different types of casting. Die-casting occurs when liquid metal is forced into a die instead of a mold, and the pressure applied there holds it in place until it hardens. This process is known for the high-speed applications it supports. Permanent mold casting involves pouring molten metal into a metal mold, using gravity or vacuum to fill the mold. Permanent mold casting can create stronger castings than die casting, but they can be difficult to remove from the final product. For this reason, semi-permanent mold castings are also available. These molds have expendable cores, making them more manageable and less expensive to remove.
What is Forging?
Forging uses compressive force to shape the metal. A hammer or die strikes a metal workpiece until the desired shape is formed. The rapid action of forging deforms and shapes the metal, resulting in unbroken grain flow, which allows the metal to maintain its strength.
Auxiliary effects of this unique grain flow include the elimination of defects, inclusions and porosity in the product. Another advantage of forging is the relatively low cost associated with medium and long production runs. Once the forging equipment is in place, products can be manufactured at relatively high speeds with minimal downtime.
What’s the Difference Between Casting and Forging?
Forging typically creates high-strength metal products that are typically harder than the metal processed in casting. Metal forgings are less likely to break when in contact with other objects. The increased strength is the result of how the metal is pressed into a new shape during forging or hammered. Unlike other methods of fabrication, in this process the grain of the metal is stretched rather than randomly aligned in one direction. By the end of the forging process, the resulting metal is much stronger than it used to be.
However, forgings have size limitations. Metal is more difficult to shape with forging because the process keeps the metal in a solid state as opposed to casting. Since it is more difficult to change the shape of a metal with forging, there is a range of sizes and thicknesses of metal for forging. The larger the metal block, the more difficult it is to fabricate.
With casting, the molten metal flows into a cavity in a mold or die, which allows more complex shapes to be produced easily. Practically any material can be cast, and up to 200 tons of products can be made. Casting is often much cheaper than forging. Casting and forging both have their advantages and disadvantages, so the better method depends on what is being made.