When researching manufacturing processes for a new component, unfamiliar terminology is often part of the territory. However, getting bogged down by unknown terms can put a wedge between solid groundwork and finding the right solution.
‘Cast’, ‘forged’ and ‘billet’ describe alternative ways of producing a component.
It’s common to come across these methods early in the research process, but it can be tricky to know how your choice could impact the project outcome – especially when performance, cost and production efficiency are all factors to consider.
At MRT Castings, we know how important it is to choose the right manufacturing process to suit the final goal of your project. So, if you’ve come across the options of ‘cast’, ‘forged’ and ‘billet’, but aren’t quite sure which (if any!) to pick, we’re here to help.
CAST
Casting is a manufacturing process where metal is melted and poured into a mould. From here, it cools and solidifies to form a component in the required shape.
Common casting methods include:
Sand Casting
Molten metal is poured into a sand mould, which is shaped to the required component. This allows the metal in it to solidify before the mould is broken away to reveal the casting.
Investment Casting
A wax pattern is coated in ceramic to form a mould. When the wax has melted away, molten metal is poured in to produce highly accurate components with fine detail and smooth surface finish.
Gravity Die Casting
Molten metal is poured into a reusable metal mould and allowed to fill the cavity using only the force of gravity, producing components with good dimensional accuracy and consistent mechanical properties.
High Pressure Die Casting
Molten metal is injected into a steel mould at high speed and pressure, producing complex components with excellent surface finish, tight tolerances and high repeatability.
At MRT, we specialise in the gravity and high-pressure die casting of aluminium alloys, using the casting process itself to create the core shape of each part.
Casting is a highly versatile manufacturing route, capable of supporting both lower-volume production (through processes such as sand casting) and very high-volume manufacture, using high-pressure die casting.
As a near-net-shape process, casting minimises material waste and reduces the amount of post-processing required to achieve the final form. A wide range of aluminium alloys can be used, with further flexibility offered through a variety of surface finishing options.
FORGED
Forged metal is produced by heating material until it becomes malleable (rather than molten) and then shaping it through compressive force.
Traditionally, forging was carried out by blacksmiths using a hammer and anvil to produce items such as horseshoes, swords and armour. In modern volume production, this process is achieved using high-pressure stamping and forging presses.
Forging can produce components with excellent strength and structural integrity, as the material’s grain structure is compressed and aligned during forming. However, forged parts typically require more extensive finishing to remove excess material, and the process is generally best suited to simpler shapes.
Designs with deep recesses, undercuts or complex overhangs are often difficult or impractical to achieve through forging alone.
BILLET
A billet is a form of raw metal (rather than a manufacturing process in its own right).
Billet material is produced as a solid length, typically through rolling or casting, and is then used as starting stock for further manufacturing. To create the final form of a component, billet material is most commonly shaped through CNC machining.
CNC machining from billet can deliver high levels of accuracy and surface quality without the need for dedicated tooling, making it well suited to low-volume or prototype applications. While machining billet material can be used for larger production runs, costs tend to increase on a per-unit basis as volumes rise, in contrast to forming processes such as casting.
It is also worth noting that billet material is sometimes assumed to offer excellent quality by default.
In reality, the mechanical properties and performance of a machined billet component are determined by the grade and quality of the billet itself. Not all billet material provides the same strength or consistency, so it’s important to bear in mind that the quality can also vary.
WHICH IS BETTER FOR my project?
There is no single manufacturing method that suits every component, and the right process depends on factors such as performance requirement, production volume, lifetime cost and complexity of design.
However, for many applications, casting offers a strong balance of design flexibility, material efficiency and scalability. It’s often the process of choice when complex shapes, integrated features or higher volumes are needed.
While forging and machining from billet each have their place, casting often provides the most effective route to production. This is especially true when components are designed with casting in mind from the start.
By working with a manufacturing partner from the early stages of your project, the entire process can be made as efficient as possible.
By ensuring that feasibility, performance and cost are carefully considered from the outset, your production partner will help you secure not only the most effective component for your application, but ensure value is generated throughout the project, too.
At MRT, we work closely with customers at the concept and design stage to assess requirements, refine designs and determine the most appropriate solution.
If you’re considering how best to manufacture a component, our team are more than happy to discuss your project and offer expert advice.
