Converting Castings to Forgings

Anchor Harvey understands that not everyone is intensely familiar with the advantages of forged aluminum products. It is a common understanding that a lot of formed metal products are castings, but what truly are casting and forging? What does each mean when it comes to aluminum, and what does each method provide when comparing end product to end product? 


The following will provide a breakdown of the casting and forging processes, the differences between the two, and why forged aluminum products from Anchor Harvey may be essential for your business. 


What is Casting?

At its most basic definition, a casting is a molten product poured into a forming tool called a “cast” or a “mold.” This cast forms a cavity in the exact shape of the product minus some more precise surfaces. The final part that comes out of the cast is called a “casting,” which is ejected out of the tool after a determined amount of cooling time. Casting is one of the oldest forming processes, with a history dating back more than 7,000 years. 


A cast is often made of sand, clay, epoxy, and other heat-resistant materials set in a very solid mass to resist the heat and the forces of flowing metal. Liquid metal is quite heavy and dense; thus, a cast needs to be resistant to the flowing metal without breaking and ruining the casting.


Part of the inherent casting process is the melting of material, which allows the liquid metal to flow into the mold freely, forming complex shapes that would be difficult to form through other methods of forming. In addition, some of the largest pieces can be made relatively quickly and easily through casting. The final product comes out as a solid mass without the need to join several small pieces of material together through welding or hot joining.


What is Forging?

Forging is primarily metal shaped through the use of a forge and the application of force. The origin of forging is not well known, but it is generally safe to assume that it is one of the oldest, if not the oldest, types of metal-forming processes. A forge is just a type of oven or heating element that brings a metal piece up to a temperature that’s hot enough to loosen the internal structure but is often far below the material’s ultimate melting temperature. Forgings tend to glow from the heat and are easily beaten and formed through the use of heavy blow hammers or powerful presses.


Forging often includes massive machinery, tons of presses, and gargantuan power hammers, especially when heavy industry parts or large stock material is produced. Forging processes often fall into the following categories:


  • Drop Forging: This process includes the use of heavy power hammers that are lifted and “dropped” onto the workpiece to deform it in the shape of the underlying die and the shape of the hammer. This can be used to form large, thick, or cold pieces because the hammer can produce momentary forces beyond that of a similarly sized press.
  • Press Forging: Presses apply a continuous force to the top and bottom of a material to form it into a shape. This may not upset the material as much as a drop-forge but often requires immense presses and incredible forces for large or thick pieces. Presses can be used with open or closed dies. Open dies refer to a forming tool that doesn’t encompass the entire part, allowing expansion of the material outside of the die. Closed dies refer to a forming tool that completely encases the material, which forms the part to the material’s exact shape. 
  • Roll Forging: Rolling a material passes a hot part between two thick steel rollers to slowly bend or shape material to a specific diameter equal to the distance between the rollers. This process is often much faster when forming round stock or other flat pieces but can also include a textured roller to place a pattern or other shape onto the workpiece. 


What is the Difference Between Forging and Casting?

Customers that are aware of the differences between casting and forging will understand the immense benefits provided by professionally produced forging and the advantages therein when compared to casting. So, what are the advantages of forging over casting?


  • Strength: Forgings are upset at much lower temperatures, meaning the material has less time or freedom to realign its grain structure. This results in a more complex grain structure that increases strength, which is very important when comparing casting and forging aluminum products to steel. Plus, the stresses from forging contribute as well to the strengthening of the final product.
  • Porosity and Cavities: Casting and forging, because of their fundamental differences, produce different pitfalls in manufacturing. Specifically, casting is prone to porosity – or the presence of small cavities within the material due to hot gases trapped in the material. This can lead to a critical failure of the part when under stress.
  • Wear Resistance: Forging aluminum offers a high degree of resistance to wear and tear without the need for specific coatings or post-forging work to increase resistance as might be necessary with castings.
  • Surface Texture: The natural surface texture of a casting is often rougher and grainier when compared to a similar forging. This may require smoothing, blasting, or other surface work if a smooth surface is needed.


These are not the only differences between casting and forging. Aluminum, being a lightweight material without the same ferrous properties as iron and steel, needs every advantage to meet the strength standards required by the aerospace and other high-performance industries. Thus, when a customer needs a good, strong, reliable forged aluminum part for their product, they should look no further than the high-quality aluminum forgings from Anchor Harvey. Request a quote today.

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