Forging Ahead

Innovation is something Yamaha Motor Company is always striving to achieve. Unsurprisingly, Innovation is also one of its five brand pillars, along with Excitement, Confidence, Emotions, and Ties.

The desire for innovation is what led Yamaha Motor Company engineers to take a fresh look at 50-year-old wheel-casting technology to give it a 21st-century upgrade.

 


Cast motorcycle wheels began replacing traditional spoked steel wheels half a century ago. The casting process involves pouring heated liquid metal alloy into a sand mould with an internal cavity in the shape of the desired part.  

Casting allows wheels to be lighter and more cost-effective to produce than steel spoked wheels, with greater freedoms on designs. However, while casting techniques have improved over the years, the part of a wheel that rides closest to the road - its rim – is still susceptible to damage. This is due to cast metal being unable to bend without breaking or cracking.

Engineers have long known that the most effective way to deliver strength in metal products is to have control over grain orientation, this can be achieved by forging the metal. In closed-die forging, a metal blank is squeezed into the desired shape using a die and a powerful press. While forging offers strength, it's not as easy or as cost-effective as the casting process.
Yamaha engineers wanted to come up with a new method of wheel production that offered the ease and cost-effectiveness of cast aluminium but with the strength of forged metal. The answer was Yamaha’s SpinForged process using an alloy blend that was formulated by Yamaha engineers specifically for the process.

Yamaha’s new SpinForged wheels begin life as an aluminium casting, but with the rim part of the wheel in an unfinished state. The wheel rim is then heated by blowtorches while being rotated. When hot enough, a forming tool - similar to a roller - is pressed against the rim as it rotates. The pressure of the roller on the rotating rim stretches the heated cast metal against a mandrel. This process flow forges the metal into the required shape.

The result of the SpinForged process is a strong rim that will bend rather than crack or break should it receive a strong impact. In addition to being stronger, Yamaha's SpinForged wheels are also lighter, with areas of the rim reduced in thickness from 3.5mm to just 2.0mm while still offering increased strength.

Yamaha's innovative SpinForged wheels first appeared on its 2021 MT-09 Hyper Naked and are now being used on an increasing number of motorcycles in its range.

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