Speaking during the Vehicle Lightweighting track at Automotive Megatrends USA, organised and hosted by Automotive World, Ana Wagner, Global Strategic Marketing Manager, Body Structures at Dow Automotive, outlined how structural adhesives enable the joining of dissimilar materials in volume production.
Adhesives make stronger, lighter cars
She commented that Dow’s “OEM customers need to provide vehicles that are appealing to customers,” but at the same time need to meet requirements for sustainability, notably corporate average fuel economy (CAFE) regulations.
Wagner explained that mass has a direct relation to vehicle efficiency and CO2 emissions, and the use of structural adhesives in place of traditional joining methods – such as spot welding – can significantly reduce this mass. This raises the possibility of using dissimilar materials, she believes, adding: “There is a key challenge in joining these materials as they have different densities and expansion rates. This is where structural adhesives come into place.”
A vehicle body may require high-temperature resistance in one area, good corrosion resistance in another, or high strength in relation to crash test performance. Dissimilar materials are becoming increasingly common in vehicle manufacturing in this sense, but pose difficulties in terms of joining.
Structural adhesives are an “enabler” for joining dissimilar materials using chemistry which allows for these materials to “work together.” Wagner noted the specific benefits of structural adhesives in vehicle lightweighting: “There is an increased load bearing capability, stiffness, improved safety and crash behaviour, NVH, as well as an extended vehicle lifespan.”
Adhesive joining breaks the trend
She explained that OEMs have to meet crash requirements as well as performance levels, which leads to a trend toward adding weight – and therefore more metal – into the vehicle. “We are trying to break this trend,” she said. The benefits of lightweighting are more pronounced in electric vehicles (EVs) where the issue of range anxiety – the fear of running out of battery charge – presents an opportunity for increased value in mass reduction. Structural adhesives help to offset the additional battery load, and to extend the vehicle range.
Steel will remain a common material in passenger cars, she predicts, which means suppliers need to look at using structural adhesives as a way of reducing excess weight created through welding. She commented: “We can’t forget steel, steel is not going away.” For every metre of structural adhesive used, there is an opportunity for savings between 0.6 and 1.1kg of mass savings. Wagner believes this increased load capability will lead to reduced steel content, “and in that effect, optimise lightweighting.”
Freddie Holmes
