Page 51 - MetalForming Magazine October 2022 - FABTECH
P. 51

  FABRICATION
HYBRID MULTITASKING
—Machining and Friction Stir Welding
...stirs up efficient EV battery-tray productivity.
The lithium-ion batteries in electric vehicles (EVs) require precise temper- ature control to maximize range and recharging capabil- ities, and to protect the battery itself. Optimum operating-
 temperature range is approxi- mately 59 to 95 F. High tem- peratures reduce a battery’s working life, and extreme heat can damage battery chemistry or cause catastrophic thermal runaway.
As a result, automakers engineer complex cooling sys-
tems for battery protection.
Most systems feature a battery container or tray with a network of tubes or channels that circulate coolant around the cells. The trays usually are located low in the vehicle and in some cases fill the entire underside of the car from the front to rear axle.
Fabricating the network of cooling tubes presents challenges that typically require more than subtractive machin- ing alone. While shops may employ subtractive machining to mill shallow channels across the floor of the battery tray, attaching the cover plate over these channels usually requires some type of welding process.
Calling on Friction Stir Welding
Friction stir welding (FSW ) repre-
48 MetalForming/October 2022
www.metalformingmagazine.com
An optimal solution for battery-tray manufacturing: a hybrid process that combines the friction stir- welding process for assembling the cover to a milled battery tray.
sents an efficient and economical process for bonding the cover plates to the battery trays. FSW joins metal com- ponents using frictional heat, created by a rotating tool with a non-consum- able central pin that moves along the joint between the parts, plasticizing the parts being joined. The process creates defect-free, strong joints that require little post-processing, use no filler mate- rial, resist corrosion and even can join dissimilar or low-melting point mate- rials, all without the arcs, toxic fumes and molten spatter produced by tradi- tional welding processes.
FSW also is a lower-temperature process compared to traditional weld- ing processes that typically apply a
significant amount of heat to melt and join the materials. And the resulting heat-affected zone (HAZ) can com- promise joint strength. Because FSW joins materials without actually melt- ing them, it creates much less heat and minimizes or avoids distortion— especially beneficial in battery-tray production.
In addition, welds made with the FSW process have the same strength as the base material. And, by using the FSW process, manufacturers can design battery trays with less material at the weld joints. Doing so enables them to reduce tray size and minimize weight, which in turn improves energy efficiency.
 















































































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