One question we do get a lot here at Project 6GR is: “what’s the difference between a cast wheel, a Spun Forged wheel, and a fully forged wheel?” And the short answer is the manufacturing processes. But how those processes matter to the end-user, that’s what we’re going to talk about in this blog.
Starting with the first process of manufacturing: CAST WHEELS
Cast wheels are the first of the three. These are the most affordable of the processes of manufacturing. Nowadays most wheel manufacturers will use a low-pressure cast manufacturing process which means molten aluminum is injected into a pressurized cast from the bottom up. This helps reduce the likelihood of air bubbles in the aluminum after the mold cools down. The video below shows how low-pressure casting works.
Spun Forged wheels:
Between CAST and Fully Forged is a hybrid of the two. This one is called Spun Forged.
Spun Forged wheels are sometimes also called Flow form, or Rotary Forged (there are a few different names for this process). These wheels start as a cast wheel that’s placed into a machine that spins it quickly, while steel rollers apply pressure to stretch the barrel downward to its final size and specifications. Different manufacturers tweak this process to their own unique manufacturing standards which is why this particular process gets branded differently. Because the aluminum in the barrel is physically being both compressed and stretched at the same time, this increases the strength properties of the barrel making it very close to a fully forged wheel. Most performance-oriented enthusiasts who can’t be at the track often enough to justify a fully forged wheel will purchase a Flow Formed style of manufactured wheel.
Here’s a brief video to show the manufacturing process of Spun Forged wheels, one thing to remember is that different manufacturers will add their own unique twist to this process that does benefit the end result. So this is not a “one-size fits all” video but it is the basics of Spun Forged wheel manufacturing.
Fully Forged wheels:
Finally the last of the three construction is the Fully Forged:
Fully Forged wheels are the most expensive of the three different manufacturing processes. While the other two can be ordered by the container load and stored in warehouses until enthusiasts make their purchase. Fully Forged wheels are completely tailored to the enthusiast’s requests. Like nice fitted Italian suits or diamond jewelry. But these aren’t just for looks. Fully Forged wheels offer the highest levels of strength characteristics and the lightest weights of any wheel. As for the manufacturing process itself, it is very involved and advanced. A solid aluminum forging gets heated to extreme heat levels which allow pressurized machines to shape the entire wheel. Then the wheel goes into the final machining process where special programming gets employed to create the design that gets drilled into the wheel itself to create the final product. For enthusiasts that spend a lot of time at the track, this is typically the choice they go with of wheel because of how much stronger fully forged wheels are.
Here’s an awesome video done by Project 6GR Wheels to showcase a few behind the scenes shots of the fully forged process: