Electrification efforts can bring over 500 lbs of weight to the vehicle once you add in the lithium-ion battery, cables, motor, and power electronics.
If you're increasing the weight of a technology designed to go fast, however, you need to slim down elsewhere.
Many automotive manufacturers have turned to a lighter material with a high strength-to-weight ratio: aluminum.
To build parts like vehicle frames, aluminum undergoes a shaping process known as extrusion. After initial heat, the softened metal flows through a shaped opening in a die and emerges as an elongated piece.
The extrusion is then cooled, or quenched, by water or air. The final step, known as tempering, heat-treats the extrusions in age ovens, hardening the aluminum by speeding the aging process.
Aluminum alloys are identified primarily by a four-digit code according to metallurgical composition. Two of the most common alloys used in aluminum extrusion are series 6000 and series 7000.
In a live Tech Briefs webinar titled BEV or ICE: Aluminum Extrusions and Tomorrow’s Vehicles, a reader had the following question for Ben Kuhn, Territory Sales Manager at Brampton, Canada manufacturer ALMAG Aluminum:
"How does 7000 alloy compare to 6000 alloy, regarding sustainability and cost?"
Read Kuhn's edited response below.
Ben Kuhn: From a sustainability standpoint, I don’t see a significant difference one way or the other. One way to differentiate the two is the cost of the alloys. It’s not so much the processing of the raw materials that costs more; it’s the actual extrusion process.
7000 series are considered a hard pressing alloy. The rate of production that you’re able to produce it at is, in some cases, less than a tenth of that of a 6000 series alloy.
Aluminum extrusion has three processes: There’s the billet preheat, the extrusion and quenching operation, and then there’s the tempering operation. The 7000 series has a more complex tempering operation that actually requires the material to go in and out of the artificial aging process a few times. That's more material handling time and more equipment utilizations, which are, of course, cost drivers.
What do you think? Have you worked with Aluminum 6000 or 7000? Share your comments and questions below.