Forging vs. Casting — What’s the Difference?

June 01, 2015

Metal forging and casting can at times be substituted for each other functionally to create a similarly effective product.  Because of this, the two processes are easily confused, and each is best suited for a different application. That being said, the properties of each process can be vastly different. So, what are the differences?

The definition of forging according to dictionary.com is “to form by heating and hammering; beat into shape”. When a component is forged, a piece of metal is being moved or “beat into shape” while still in its solid form.  This obviously takes a lot of force to accomplish; the greater the size of the metal part being forged, the more force needs to be exerted to have the same result. For this reason, forging size is restricted by the size and/or capacity of the forging equipment available.  Materials which can be used in forgings most commonly include aluminum, steel, nickel, and copper.  Once a product is forged, machining may be necessary to reach the desired final shape and tolerance. Forged parts, in general, can be stronger than their cast counterparts

In contrast, casting is defined as “to receive form in a mold”.  In layman’s terms, molten or liquid metal is poured into a mold (either closed or open) and cooled to a solid state where it retains its shape. Casting tends to be most practical for larger applications. Because a more precise shape can be obtained initially through casting than through forging, frequently only finishing processes need to be completed on a cast part as opposed to a forged part. Materials best suited for casting are steel, brass, iron, aluminum and tin. Casting tends to be generally cheaper than forging, but there are many methods of casting, including: investment casting; die casting; permanent mold; and vacuum process molding, which can all affect pricing, tensile strength and cosmetic appearance. 

Your manufacturing partner should be able to not only guide you through the process, but also make recommendations on which process will be best for your applications to create the best finished product possible.