“Glued cars” are safer and more economical. It is no wonder then that adhesives have entered what used to be the domain of welding in the automotive industry. For instance, in 2001, 33 linear feet (about 10 meters) of adhesive were used for the body of the BMW 7 model, today 500 linear feet (about 150 meters) are used. About 9% of annual adhesive production is used in vehicle construction.
Today a car contains up to 40 lb (18 kg) of adhesives. And for good reason: crash tests have demonstrated that glued cars do better than welded designs. What is more, adhesives do not affect how parts are assembled. Other techniques including, welding, riveting or bolting impact the rigidity of assembly materials. In the event of an accident, adhesives behave like a buffer.
That said, automotive engineers design car bodies so that as much impact energy as possible is transformed into deformation energy, rendering it harmless. This gives maximum protection to passengers. Today, so called crash-resistant adhesives are used for this purpose. However enhanced safety is not the only benefit of adhesives in vehicle production. If doors were welded, the outside would have to be laboriously reworked to ensure a good appearance.
For glued doors though, there is no need for reworking, resulting in lower production costs. In order to ensure that the windshield, which is subject to enormous loads (imagine the headwind when riding down the highway at 80 mph) and remains perfectly in place in the frame, the automotive industry uses advanced high performance adhesives.
These guarantee perfect hold overall, even under extreme conditions including wind, rain or hailstorm, blistering heat in the summer or bitter frost in the winter. Directly glued, the front and rear screens, ensure lower air resistance, thereby reducing gas consumption.
For modern cars, manufacturers use a range of materials besides steel sheets. This mix of materials is also held together by adhesive. Incidentally, the use of adhesives is not limited to car production but is used in other vehicles as well. While an average rail car, built between 1981 and 1993 contained some 22 lb (10 kg) of adhesive, some modern rail cars used today weigh in with up to 1100 lb (500 kg) of adhesive.