Forging Versus Casting: Which is Better?

It’s not uncommon for manufacturers to rely on an outside firm for fabricating custom metal parts. However, because these metallurgical firms often specialize in different methods, it’s important to know what works best for the desired parts in question. Two common methods, used for a wide range of metals, include forging and casting. To find the right firm to partner with, first know what these methods are and how their results differ.

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What is Casting?

Casting uses specially designed molds and liquefied material to produce desired components. The mold contains a space inside it of the product’s intended shape, and molten metal is fed into this space and left to cool and solidify. Casting processes vary based on the material comprising the mold and the method of feeding material into it; this can range from pouring metal into packed sand molds to high-pressure injection into reusable dies. The process allows for parts with complex geometries and high precision in dimensional specifications.

What is Forging?

Forging involves shaping a solid piece of metal by localized compression, which causes plastic (permanent) deformation of the material. Traditionally, this involved hammering the workpiece on an anvil—many types of forging still do this mechanically. The metal’s shape is directed by the die that it rests upon or in and the placement of force. Some processes may use presses or rollers, instead. The metal may be left cool or heated to varying degrees while being forged, which affects its crystalline structure. Forged parts are desirable for mechanical strength—steel forgings in particular yield high-strength components that can’t be cast.

Which Should You Choose?

Both casting and forging have their applications in modern industry. The nature of casting enables flexibility in design and produces well-shaped parts that need little machining to finish. However, the material is porous and its tensile strength suffers for it. Forging, on the other hand, strengthens work metals by altering their grain structure, and upfront costs are generally lower as finely-shaped dies aren’t required. This does result in a loss of precision in shaping the metal, and some alloys are very difficult to work while solid.