Striving to reduce vehicle weight in order to increase fuel economy, Honda focused on Friction Stir Welding (FSW) and developed a new technology for the continuous welding of steel and aluminium. This technology generates a new and stable metallic bonding between steel and aluminium by moving a rotating tool on the top of the aluminium which is lapped over the steel with high pressure. As a result, the welding strength becomes equal to or above conventional Metal Inert Gas (MIG) welding.
This new technology contributes to an improvement in fuel economy by reducing body weight by 25 percent compared to a conventional steel sub-frame. In addition, electricity consumption during the welding process is reduced by approximately 50 percent. It also enabled a change in the structure of the sub-frame and the mounting point of suspension, which increased the rigidity of the mounting point by 20 percent and also contributed to the vehicle's dynamic performance.
Furthermore, Honda established a new method to apply this technology to mass-production vehicles. Conventionally, FSW required use of large equipment, but the carmaker has developed an FSW continuous welding system applied to a highly versatile industrial robot. This system also can be used for aluminium-to-aluminium welding and thus, the welding system with the same specifications can be used for production of a full-aluminium sub-frame.
Honda also developed a non-destructive inspection system using a highly-sensitive infrared camera and laser beam, which enables an in-line inspection of the bonding location for every unit.