Friction Heat Welding

Until now welding two different metals such as steel and aluminum has been a difficult task. By optimising the rotating tool shape and joining characteristics, and by using galvanized steel on one side, joining steel and aluminum has been made possible.

The process is similar to that of joining two pieces of aluminum, when a joining gun holds the parts from both sides with a welding tool. The joining tool is then made to spin while force is applied, which in turn generates frictional heat that subsequently joins the aluminum materials to the steel sheet metal.

Compared with conventional joining techniques such as riveting or clinching, steel and aluminum spot friction welding makes it easier to join materials that are difficult to deform, such as aluminum casting and high tensile steel.

Additionally, running costs can be reduced because riveting becomes unnecessary. The technology contributed significantly to Mazda’s vehicle weight reduction “gram strategy” program during the development of the MX-5 sports car, as well as lowering costs.

Three Layer Wet Paint System

Coating has always been the process that creates the greatest environmental burden during automobile production. The volatile organic compounds (VOC) generated during a vehicle’s coating procedures account for about 95 percent of total emissions for the entire production process. Additionally, each coat requires its own baking and drying process and these are responsible for roughly 60 percent of all CO2 emissions.

Development of the unique Three Layer Wet Paint System

Various coating processes have recently been adopted by many automobile manufacturers around the world that reduce VOC emissions. The variety of these processes, however, actually leads to an increase in the CO2 emissions of between 5% and 60%. In this current age, when the emphasis is on the urgent issue of preventing global warming, these methods are no longer appropriate.

Mazda has developed the unique Three Layer Wet Paint System, the first technology in the world to reduce VOC and CO2 emissions simultaneously.

Getting closer to solving all the problems of vehicle coating

As its name implies, the Three Layer Wet Paint System is a one-step baking and drying coating method that applies three layers in succession-primer coat, base coat and clear coat-while still wet, without drying in between. By eliminating the drying process formerly required after applying the primer coat, CO2 emissions are reduced 15%. In addition, a new low solvent content paint jointly developed with paint manufacturers, applied with high-precision coating equipment enables gains in coating efficiency leading to reductions of 50% in VOC emissions.

Until recently, it was thought that using a wet paint system would lead to problems of paints mixing between the successive layers. For this reason other companies’ coating techniques require a drying stage following the intermediate coat. Mazda overcame this issue through innovations such as the newly developed interface control resin that was added to the paint. The Three Layer Wet Paint System also displays a deep tone finish that is unique to this method.

Mazda commenced development of this technology in 1994. The perfected Three Layer Wet Paint System was introduced after four years of experimental verification and has been adopted across all Mazda’s production facilities in Japan.

This pioneering technological development has been awarded the Japanese Environment Minister’s Prize, the METI (Ministry of Economy, Trade and Industry) Minister’s Prize and various other awards.

Mazda has developed a state-of-the-art technology that may well become the international standard for vehicle coating; the process which is currently the greatest obstacle to environmentally friendly automobile production. We will continue to pursue the ideal of a single solution to all the issues facing the coating process.

Power Retractable Hard-top

A total of four roof motors – two on each side of the vehicle – transforms the car from coupe to open-top roadster in just 12 seconds. Before opening or closing the hard-top, the windows (if in the up position) are automatically lowered by approximately 100 mm to make sure there is enough room for the roof to fold back unimpeded.

Innovative plastic composite materials are used for the hard-top. In its efforts to keep additional weight for the hard top version as low as possible, Mazda used two different kinds of materials, sheet moulding compound for the outer panels and glass fibre-reinforced polypropylene for the inner panels of the retractable roof.