Ford, GM innovate to remove weight

With plasma transferred wire arc, electricity in a plasma cloud vaporizes metal wire, which is then sprayed onto the cylinder walls of an engine block with an air jet. Only the sections of the cylinder walls that the piston rings travel over are treated. Ford is saving more than 6 pounds per engine with the process. Photo credit: FORD

Despite cheap gasoline prices in the U.S., the march to remove weight from light vehicles continues.

Over at Ford, the Shelby GT350R’s new 5.2-liter, V-8 engine is the first Ford engine to be made in-house that uses plasma transferred wire arc process, or PTWA. Ford has used PTWA before, but has outsourced the work.

Ford actually patented the process and licensed it to Nissan, which uses it in the mighty GT-R supercar.

PTWA does away with the heavy (3-mm thick) cast-iron liners in an aluminum engine. Instead, electricity in a plasma cloud vaporizes metal wire, which is then sprayed onto the cylinder walls of the engine block with an air jet. Only the sections of the cylinder walls that the piston rings travel over are treated. The result: Ford saves more than 6 pounds per engine.

That’s huge. Engineers struggle to find every ounce of weight in a car that can be left at the curb.

Now, Ford has installed the expensive plasma equipment at its Essex Engine Plant in Windsor, Ontario, to do the job in-house. So far, only the engine in the Shelby is getting the PTWA treatment. Ford won’t say if the PTWA costs more than pressing in the old-fashioned cylinder liners. But the PTWA process could have more applications in the future, including four-cylinder motors.

“It could benefit any engine,” said Ford spokesman Paul Seredynski. “Bringing it in-house shows our commitment to the technology.”

Ford’s weight-reduction efforts are part of a larger industry trend that is gaining traction.

The structure is aluminum intensive, but the Cadillac CT6 also features 13 different materials customized for each area of the car to simultaneously advance driving dynamics, fuel economy and cabin quietness. Sixty-four percent of the CT6 body structure is aluminum, including all exterior body panels – and the mixed material approach saved 198 pounds.

Cadillac recently showed a sectioned body-in-white of the upcoming CT6 sedan, which is more important than you might think.

The car’s outer skin is aluminum -- a first for a GM car -- but underneath, the aluminum and steel unibody is the first high-volume application of GM’s mixed-materials approach to reducing weight.

Take a close look at the CT6’s steel and aluminum body parts. Notice how they are joined with welds, fasteners, and adhesives? The area with the concentric circles is the welded portion. This is a preview of how GM will build the next generation of its full-size Chevrolet Silverado and GMC Sierra pickups. GM won’t be following Ford with a full aluminum-bodied truck.

A closeup view of the aluminum welding on the Cadillac CT6 body. Photo credit: RICHARD TRUETT

And here’s another interesting thing about the CT6: An inner section of the hood will have a steel section welded to an aluminum component, an industry first, GM says. The CT6 uses six different blends of steel and six types of aluminum to reduce weight and provide strength.

GM spokesman Dan Flores said the steel and aluminum parts are welded together using GM’s current production-line welding robots that have been slightly modified with different tips.

Delphi Automotive is working to remove weight from the vehicle’s wiring harness by switching from traditional copper wires to aluminum.

“When you go to a substitute material like aluminum, for example, it’s roughly half the weight of copper,” Jeff Owens, Delphi’s chief technology officer, told me. “You have to use a little more aluminum to get the current carrying capability, but if you can take 10 or 20 pounds out of the electrical architecture, that’s a huge pickup. Automobile manufacturers are looking to take out ounces and grams.”

Cheap fuel prices may have consumers stampeding to trucks and SUVs right now, but U.S. regulators have not and likely will not relax or delay the strict 54.5 mpg fleet average standard that must be met by 2025.

Expect more innovations like these in the next few years.

You can reach Richard Truett at rtruett@autonews.com

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