Page 49 - MetalForming Magazine February 2023 - Metal Forming for the Automotive Industry

given the evolution of automotive- component manufacturing both in part design and in production volume, especially related to battery systems.
“We’re seeing more straight lines in body structures as opposed to flowing curves that would require traditional die stamping,” Davis says. “This lends itself to sheet metal fabrication processes such as tube processing and cutting, bending channels, etc.”
These fabrication processes prove efficient—and offer synergy for suppli- ers of sheet metal-fabrication and laser welding/trimming equipment, Davis and Fedai report—due to an increase in low-volume, high-mix products.
“Now, especially at the beginning of this major electrification effort, comes a need for lower volumes, maybe 50,000 or less, and a mix of those parts,” Davis says. “This makes equipment and process flexibility a must. A process designed around rigid stamping tools in this scenario becomes time-consuming and less cost-effective.”
Dealing With Battery-Tray Disruption
Flexibility becomes even more important when considering the cur- rent lack of standardization in EV-bat- tery platforms.
“I would say that we're as far away from a standardized battery-package design as we can be right now,” Fedai offers. “The battery tray obviously is
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the disruptor in the traditional body- in-white design. For instance, among OEMs, one leans toward steel for bat- tery trays and is heavy on roll forming, while another focuses on aluminum extrusions aluminum plates. A third employs laser-cut and -welded tube structures.”
Davis agrees, citing another example.
“A large cast-aluminum structure makes up a portion of the body designs in some platforms from one automak- er,” he says. “This represents a totally new approach, and these designs require laser cutting or trimming, and then welding. Then the inverters and some big-module electrical compo- nents that make up the brains of bat- tery systems are assembled, with bolts or laser welding for the covers to encase the whole system. Laser welding pro- vides a good approach here, as it her- metically seals the structure.”
Automotive designers now seek to counter the hefty weight of these bat- tery compartments via lightweighting.
“With EVs, we see a trend toward lightweight materials where possible,” Fedai says. “The curb weight of an EV typically runs about 20 to 25-percent higher than a comparable internal combustion-engine vehicle. To combat this, automakers increasingly employ lighter-weight materials, including hot- stamped steels and aluminum alloys, which we hadn’t seen in the past.”
This trend increases the need for flexibility in joining solutions, as does
A trend toward larger and fewer assem- blies in automotive designs makes laser welding and laser cutting attractive options, especially in relation to tailor- welded blanks used for door rings and more—another trend.
the trend toward less assemblies within vehicles.
“This includes bodyside tailor-weld- ed blanks to produce an entire door ring or an entire bodyside, specifically via hot stamping,” Fedai continues— “never the case before. Now we see full bodysides, door rings and double-door rings that use more material. Of course, we need laser welding to create the tai- lor-welded blanks.”
Laser welding, a single-sided process, opens up possibilities as an alternative to spot welding, which requires two- sided access for the electrodes.
“This makes laser welding attrac- tive...it’s just a matter of getting in front of design engineers before a design is frozen to allow flexibility to design for easier, single-sided access to weld areas,” Davis says.
And, of course, fitup matters, as does material coating.
“In designing for laser welding, fitup is critical to success,” says Fedai. “And, especially for lap-joint welds of coated material, the lighter the coating the better the ability to laser weld. Sec- ondary operations such as dimpling— which works as a spacer between two sheets—can improve conditions for laser welding, but in general, no coating or a thin coating is preferred.”
Laser welding can be a game chang- er, concludes Fedai, “in the right cir- cumstances, with the right training and with the right product design. Some designers have a mentality of designing a spot-welded or arc-welded product, then just right-clicking in the CAD pro- gram to convert it to laser welding. Unfortunately, it’s not as easy as that. The product must be designed with laser welding in mind. We’re trending toward greater use of laser welding in automotive applications with OEMs learning more about how to design laser welding into manufacturing—I can't preach such education enough.”
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