From what we've seen so far, the aluminum decision appears to be a win-win-win for fuel economy, corrosion resistance, and durability. Aluminum weighs about one-third as much as steel. As a result, 500 of the 700 pounds that the new F-150 lost compared with its predecessor were lost in the body.
The tough part, though, is convincing some of the most loyal buyers in the business the company hasn't gone off the deep end. Aluminum has long been considered a less sturdy material for heavy-duty applications, largely because most of us experience aluminum in wimpy applications such as soda cans. To that end, Ford invited a group of journalists to its Dearborn Research and Development Center to show off some of the testing they've been carrying out for more than five years. The company released a bevy of torture-test videos showing how badly they beat up the new trucks. But the attention to detail at the atomic level is likely even more important.
From a basic engineering perspective, switching to aluminum is really just a matter of changing material properties in the computer-aided design and digital-simulation software. Selecting the correct gauges of sheet aluminum becomes a matter of figuring out what passes digital tests and then sending test trucks out into the real world for man-made punishment. Ford completed those practical tests by cleverly building exact copies of the previous-generation F-series out of aluminum and putting them out in the field into harsh working environments—think fleet service for mining and construction operations.
These tests lead to Ford selecting a thicker aluminum for the bed floor and redesigning an access panel. But for the most part the aluminum passed with flying colors. One of these experimental bodies was subjected to 150 percent of Ford's 150,000-mile-durability-testing cycle and passed easily. In fact, digital design has advanced so far the cabins on the finished 2015 trucks had zero durability failures in any test. That's a first for any Ford pickup.
The physical geometry of the metal is the easy part with aluminum. The bigger challenge is dealing with and testing for galvanic corrosion. Galvanic corrosion is not like the red rust we're used to with steel-bodied cars, where environmental oxygen chemically bonds with iron atoms to form iron oxide. Galvanic corrosion takes place through the exchange of ions between metals bathed in an electrolyte. In essence, any time dissimilar metals are placed in physical , a battery is created, and the atoms in exchange metallic ions and degrade the actual atoms at the surface. Over time this creates pitting and metal fatigue.
Ford is fighting this process by electrocoating the aluminum panels to electrically and physically isolate the metals, and by using new coatings on all body bolts. To test the long-term durability of these kinds of joints, engineers normally bathe body panels in a saltwater spray during a hot/cold environmental cycle—this encourages the formation of iron oxide. But with aluminum that was just too slow. So they switched to a corrosive acid bath and found that tweaking the metallic coating on the bolts protected the metal admirably.
If Ford has done its work properly, then bodies on these trucks will outlast every other part. This has lead to some interesting work on the subject of end-of-life recycling, but it removes any concern about a tailgate or fender or cab corner ever rusting through.
Check out some of Ford's own testing videos. You can see the rest .