by Chris Anderson
Overcome the challenges of robotic welding of aluminum in truck manufacturing
Manufacturers of over-the-road vehicles (also referred to as OTR or long-haul trucks), and to a lesser degree car manufacturers, are improving fuel economy and reducing the weight of their vehicles with aluminum. However, assembling frames, trailers and other components made of aluminum requires welding, and there are important differences between robotically welding steel components versus those made of aluminum.
The challenges with robotic welding of aluminum are not necessarily more difficult than steel; they’re simply different. For instance, steel welding wire is fairly hard and stiff, whereas aluminum welding wire is softer and more difficult to feed or push into a robotically controlled welding arc. It’s critical to take a close look at the wire delivery system your welding robot will use, as well as the different wire feeders and torches, which are called push-pull torches. As a company that works with welding equipment manufacturers closely, we’ve seen more and more of them enhance their product line for the robotic push-pull welding of aluminum.
While it’s possible to retrofit the tooling end of a robot configured for steel welds to instead weld aluminum, there are elements to address. First, the torch and feeding systems for aluminum welding often come with more process features, such as different pulse schedules to enhance welding with aluminum wire, which has a lower melting temperature than steel. This reduces spatter. Second, power source manufacturers can now create a dual pulse to create a ripple in a bead; this makes aluminum welds more aesthetically appealing. We’ve added the control of these pulse parameters to our robots.
Another consideration for making the move to welding aluminum is understanding it has several different alloy configurations; these affect the strength and properties of the weld, as well as the ability to weld.
For example, welding a steel trailer frame requires a certain amount of weld length. If a trailer manufacturer switches to aluminum, the frame will likely need additional weld length and a different distribution of welds on the trailer. Due to the density of the required weld locations, we might recommend seven axis or extended reach robots to maximize productivity in a similar footprint as
a steel welding process. This keeps the manufacturer’s production line from stretching out as more welds are needed to achieve the proper weld strength.
The key is to understand upfront what effect there is on your production line by moving from welding steel to welding aluminum. In some cases, to maintain throughput, it might require using multiple robots, or it could simply mean repositioning the robots to work in closer proximity. Yaskawa has the ability to control multiple robots from a single controller/teach pendant, which simplifies safeguarding and includes software that prevents robots from colliding with each other.
People with a great deal of steel welding experience might look at their welding production line and assume a relatively straightforward change to aluminum, but aluminum welding is a different game with altered rules that govern:
- Equipment selection, particularly the power source, torch and feeding system
- Processing of the weld, which may take longer at an arc start and arc end
- Welding travel speeds that are sometimes faster with aluminum than steel
Lightweighting is about achieving efficiency and profits. Take a studied approach to making the shift from welding steel to welding aluminum, so your production and process move is as efficient and profitable as your end goal: making lighter trucks and trailers that haul more freight. SMT
Chris Anderson is associate chief engineer at Yaskawa America Inc. – Motoman Robotics Division.