A few years ago, Ford attracted a lot of attention when they announced that they were replacing the steel body of their F-150 truck with aluminum instead. While this was a risky approach which could have cost them big money, since it meant closing body shops, they believed that these risks would pay off if they could create a lighter truck. Now, General Motors are also looking at ways of making their vehicles more lightweight. However, rather than take the same approach as Ford, they have instead been hard at work researching ways of spot welding vehicles with a mixture of materials including aluminum- all while making use of their existing body shops and tools.
All of that research was taking place mostly behind the scenes, but now GM are bringing their innovations to the masses, by announcing that some parts for the new Cadillac CT6 sedan will involve welding steel to aluminum- an extremely exciting move that could totally change the way we approach car manufacturing. Naturally, other manufacturers are keen to get on board. Unlike Ford’s approach, which no other companies have seriously considered, the GM approach is attractive because it can be done without needing to change the facilities and equipment used in manufacturing these lighter vehicles.
Essentially, car and truck manufacturing all boils down to making metal. The increasing use of aluminum in vehicles therefore posed a big problem to many auto plants, since they now need to rethink their methods. GM first tried out aluminum when they added an aluminum liftgate to the otherwise fully steel Tahoe hybrid back in 2008. That approach is now standard at GM, but it’s taken eight years for this innovative approach to spot welds to reach that point. Professional welding equipment and helmets are always used during the process.
Now, it’s time to apply that spot welding to the joining of steel and aluminum. This step isn’t all that complicated, since not only is the process faster and less expensive, but auto plants are also already equipped to perform it. Again, the CT6 will be the prototype for this approach, although it shouldn’t take another eight years for it to be rolled out across the entire GM range.
However, there were some issues that needed to be overcome before they could actually put this theory into practise. Aluminum is molten at 655 degrees Celcius, whereas steel needs almost 1,000 degrees more heat before it melts. What’s more, when the two layers of molten metal come into contact, it forms a brittle layer which makes the weld much weaker. GM solved this problem by pulsing a current through the metals, heating and cooling them as necessary to keep that brittle layer as thin as possible. It’s an innovative approach which could save millions, since it doesn’t need any special equipment, and can therefore be carried out in all of their present body shops.
On the other hand, Ford’s approach was much costlier. After manufacturing steel trucks for some 70 years, they found it hard to break old habits. Instead of using an integrated approach like GM, they instead completely shut down their Dearborn Truck Plant in August 2014. They then completely rebuilt the body shop using robotics and new tools designed to build with aluminum, at a cost of $359 million. They also spent an additional $484 million building adjacent Diversified and Stamping facilities.
Once Dearborn had been rebuilt, they then repeated the process in their Kansas City plant, where the F-150 and new line of Transit vans are produced. This time, the process cost a staggering $1.1 billion. As if that wasn’t enough, the long downtime periods had a big impact on profitability. It led to a slow launch for the new F-150, and Ford’s revenue took a $2 billion nosedive.
As well as costing Ford money, the move also had a big impact on their reputation. While critics pointed out that Ford’s actions had a big impact on their inventory, which affected their profitability throughout the year, Ford themselves noted that the new, more profitable trucks showed strong sales, meaning that in the long-term, the risk is likely to pay off. What’s more, they are planning to roll out their new approach across other vehicles in their range, such as the Lincoln Navigator and Ford Expedition.
On the other hand, GM isn’t interested in applying their aluminum weld strategy to just one type of vehicle. Instead, they want a flexible approach that would allow them to weld different materials together for one vehicle in a particular plant, while still being able to make purely steel vehicles in that same plant.
What’s more, welding aluminum to steel can save weight and cost in some surprising areas. For instance, as well as welding an aluminum roof to a steel body, weight can also be saved by using welding in the place of rivets. These rivets, while relatively small on their own, quickly add up, and not only does welding cut down on that weight, but it could also save some $100 in manufacturing costs per vehicle. By exploring innovative solutions like this, GM will be able to dramatically reduce the weight of their vehicles- without taking the huge risks that Ford has.
