U. of Michigan researchers: New welding process could make vehicles lighter, more fuel efficient

University of Michigan researchers have developed a new welding process that could revolutionize the way vehicles are made, the school said in a news release.

By combining metals and plastics, the team has managed to create vehicle structures that are up to 40% lighter than traditional all-steel or all-aluminum designs, while also being stronger and more environmentally friendly, the university said.

The breakthrough was made under the leadership of Pingsha Dong, an engineering professor. Dong and his team were able to achieve the previously impossible task of welding plastic and metal directly together, creating a process that could significantly reduce manufacturing costs and improve the efficiency of vehicles.

"Lighter weight brings a variety of advantages, chiefly better efficiency," Dong said. "Gas-powered vehicles could see better fuel economy, while electric vehicles can get more range. Vehicles with multimaterial structures can also handle better and offer improved safety."

The research, which has been detailed in the Journal of Manufacturing Processes, involved using an off-the-shelf machine that looks similar to a drill press with a cylindrical spinning head. The metal is placed on top of the plastic, and the head is lowered onto the two materials, creating heat and pressure that bond the two materials together in either a spot weld or a linear weld. 

According to Dong, any metal can be bonded directly with any plastic that contains an adequate amount of oxygen-carbon compounds. The key is to calculate the “sweet spot” of heat and pressure that will weld a given combination of materials, and the team can work with manufacturers to determine that. 

For plastics that don’t have enough oxygen-carbon compounds, such as polypropylene, an inexpensive plastic film can be placed between the two materials to “seed” the bond with oxygen and carbon.

Dong and his team have already patented the process and are working with equipment makers to develop commercial equipment that can be licensed to automakers and other manufacturers. Dong believes the technology could be in use within the next two years. In addition to improving the efficiency of gas-powered vehicles and increasing the range of electric vehicles, the new welding techniques could also improve EV battery packs and enclosures. 

Traditionally these are multilayer structures that are usually held together with adhesives and mechanical fasteners, making them difficult to take apart for repair or recycling. Welded battery packs could be taken apart and reassembled more easily, while also being lighter, cheaper to manufacture and easier to keep cool.