What is a Forged Wheel?
Other than exotic materials like magnesium or carbon fiber, you won’t find a lighter or stronger wheel than a forged aluminum wheel. Why is that, though? How is it any different from any other aluminum wheel? That’s what this article aims to answer.
Much like the Steel vs Cast Aluminum vs Flow Formed Cast article, you’ll probably want to read it and the Wheel Basics articles before continuing to read this article. A few terms may get glossed over here only because they are fully referenced in those previous ones. So, if you happen to get lost on a term, head back to those to learn more.
The Billet Material
In most cases, the aluminum used in a forged wheel and a cast wheel are the same alloy composition – either AISI 6061 or AISI 6082. Where they separate is how the wheel shape is formed. Instead of melting the aluminum alloy into a liquid form and flowed into a cast mold, it’s a billet of aluminum.
That term gets tossed around quite a lot when you talk about aluminum parts. What it refers to is that the aluminum (and steel when you talk about “billet steel”) is extruded by continuous casting or hot rolling into square, flat, or round stock that your aluminum part is made of.
That extrusion process creates a stronger material from the get-go and is why a billet part is of a higher quality and stronger in nature. The metal grains are compressed, ordered, and lengthened as you extrude it and is how the metal gains strength. Once that process is done it’s on to the forging line.
Forging Process
Not all forging processes will be like this, but most will generally be done in the following way. First, the billet is heated and pressed forged into its initial shape. It has a bit of its wheel face designed in but there is no barrel, just a skirt of aluminum.
Here, it’s very similar to the flow formed cast wheel process in that the piece is sent to another machine where it is heated. A forming die is then pressed to form the wheel barrel as it spins on another machine. The flanges, bead seats, and drop well are all formed at this point.
Before receiving any heat treatment to get the wheel to its final hardness, the wheel is cold spun, and any flashing created during the hot forming process is removed. The heat treating is done so that the wheel is hard but no so that it becomes too brittle.
You want a wheel that is rigid and that is what the heating process is designed to achieve. After treatment, the wheel is then machined, media blasted to remove any corrosion that may have built up, and finished by painting, powder coating, or polishing and sealing.
Strength and Lightness
The use of a single billet of aluminum to create an entire wheel creates a wheel of unequaled strength for the final weight. It’s the choice of wheel design in racing where exotic materials aren’t allowed or just aren’t feasible. As the forging process becomes cheaper and better, we’re starting to see more forged aluminum wheels on Jeeps where it was more common to hear about the beadlock ring being the only forged aluminum part.
Why Do I Want Strength and Lightness if I’m Using a Large Off-Road Tire?
In addition to the weight of wheels continuing to go down, we’re also starting to see the same trend in our off-road tires. Even large MT tires today weigh less than their counterparts of just a few years ago by using materials other than steel to create the tire carcass. Even so, you still want to decrease the rotational and un-sprung weight at your Jeep’s hubs to decrease the effort your engine requires to turn them over.
It’s here where small changes can have very big impacts on the performance of your rig. It’s not just sports cars that will see these advantages. The less weight at the axle is horsepower the engine can transfer to the ground instead of trying to turn the wheel and tire. Less weight is less rotational momentum that your brakes must stop, though that is a very, very small gain when compared to the benefits to power and acceleration.
It’s Not All Roses
However, there is a rather large disadvantage when it comes to forged wheels. Despite prices falling in recent years, you’re still talking about $3,000 to $5,000 or more for a full set of wheels, including the spare. That’s just for the wheels and no tires. That’s a lot of money to take and bash around with on the trail but if you’re looking for the best your money can buy, you’re not going to find anything better than forged wheels.
There is one thing all these wheels can have in common: the addition of beadlocks. That will be our final look into wheels. Why and When Do You Need Beadlocks?