Tech Tip: Forged Milled Wheel Technology

Turbos can be made from a variety of materials and constructed in multiple ways. The difference in materials and manufacturing processes is the difference between good, better and best.

The picture above shows the forging process. From left to right, the compressor wheel is transformed, first through forging and then through lathe machining to become the completely milled wheel.

At BorgWarner, we use the best—forged milled wheel technology—for most of our new and existing turbo models. This innovative process produces a highly engineered, high-quality product that lasts longer. By hammering material properties into the desired shape and grain structure, we better support wheel strength and functionality, and ultimately, increase safety and enhance long-term durability.

Here’s how it works:

• The compressor wheels start out with a round piece of aluminum and then cut into desired lengths.
• This is either extruded or roll-formed into shape, refining the metal's grain.
• During the forging process, the metal grain gets finer, adding strength and fatigue resistance to the material.
• Once the forged blanks are formed, it is then machined into a predetermined shape.
• It is then milled to its final shape, which produces a much more consistent blade shape vs. casting. This process is very repeatable, producing less variation.
• Additionally, every lot is X-rayed to ensure the forging is defect-free.

"Forging adds more steps to the manufacturing process, but improves the final turbo product durability,” says Seth Temple, Senior Application Engineer. “It makes the material more dense and aligns the grain structure to improve durability. Forging also improves low cycle fatigue, which directly determines turbo life."

Better technology, stronger materials and smarter processes are all part of BorgWarner’s forged milled wheel technology. Most of all, this innovative technology provides confidence that the product you’re buying offers high quality and a longer life than any off-the-shelf option.