Welding method uses 40x less energy, produces welds 10x stronger
It's hard to miss the steady stream of Toyota Siennas filing out of the parking lot after a soccer game. This top-selling minivan has become a staple vehicle for many families, and parents of young children know how invaluable its automatic sliding doors are for added convenience.
Now BYU engineers have partnered with Toyota to make future versions of the minivan — and its sliding doors — safer, stronger and more environmentally friendly.
A new welding technique developed by BYU and Toyota for the Sienna’s sliding doors uses 40 times less energy, emits fewer emissions, and produces welds that are 10 times stronger. This new process, called refill friction stir spot welding, could prove critical as Toyota and other car manufacturers rely more and more on lighter aluminum parts.
“Ultimately we are looking for ways to do things more efficiently, greener and cleaner,” said Yuri Hovanski, the BYU manufacturing engineering professor overseeing this project. “It is super exciting to demonstrate that what we're working on is helping the environment. Ultimately, as engineers, we believe in trying to be good stewards of the planet.”
To reduce vehicle weight, especially in automatic sliding doors, car manufacturers are increasingly transitioning from steel to aluminum body panels. However, the current welding process, resistance spot welding, presents challenges since it was designed for steel. Based on the same fundamental principles, refill friction stir spot welding specializes in aluminum and tweaks the procedure based on the unique chemical properties of the different metals.
The new welding process joins the metal without ever melting it — the metal remains in a solid state. Pressure is applied and a pin inserted into the metal, softened by friction. The two sheets of aluminum are stirred together with a tool, and when pressure is released, the hole fills in, leaving a strong quality joint. The new joints are also strong enough that less spot welds would be required in a vehicle. Since no filler material is required and less equipment is used, the new process cuts down on consumables, leading to greener manufacturing.
“Right now, Toyota has been using the cleanest technologies they have available to them, but what BYU research is bringing to them is a technology that is a game changer,” Hovanski said. “They partnered with us to be able to essentially do a side-by-side comparison of the same model of car with new welding technology.”
This partnership initially began when the Toyota team saw Hovanski at a conference showcasing the technology innovations in the new welding process that has been pioneered at BYU for other uses. Hovanski and BYU graduate student Damon Gale visited Toyota's manufacturing plant in Indiana where they evaluated the current production. This gave them further insights on how a new welding process could be used in the aluminum sliding doors.
Hovanski and his students published papers with SAE International and Journal of Manufacturing and Materials Processing highlighting their process, with additional papers in the works.
“Our research concludes that refill friction stir spot welding is a preferrable method for joining aluminum body panels and is positioned to become the new standard in automotive manufacturing,” said Gale, who was first author on the SAE International paper.
Fellow BYU graduate student Ruth Belnap and undergraduate student Taylor Smith have also played pivotal roles in the ongoing research. Jeremy Coyne and Kate Namola from Toyota Motor North America were listed as authors on the SAE International paper as well.
“Working with a partner like Toyota has been great because they are very sensitive to wanting to use cleaner technologies,” Hovanski said. “It creates a meaningful situation that aligns well with our mission here at BYU.”
Learn more about BYU's Manufacturing Engineering program here: https://mfgen.byu.edu/
