Abstract
In motorcycles, the materials of frame have been switched from steel to aluminum for the purpose of reducing weight while improving the rigidity of chassis. It was made possible to use aluminum frames for a number of commodity categories, by the development of technology through new structural designs to make the most of the characteristics of aluminum, the advancement of computer simulation system and the progress in material and production engineering. As the result of adopting aluminum for the frame, much higher performance has been realized by achieving a 40% reduction in the developed frames consisting of extrusions and castings for sports-oriented motorcycles and by suppressing the increase in fuel consumption. For low-priced utility vehicles such as scooters, the manufacturing process has been simplified by the development of the die cast two-split module frame. By utilizing recycled materials for the frame, the reduction of energy consumption by 57% has been achieved in the stage from the raw materials to manufacturing as compared with steel frames. For further development of technology for reducing weight in the future, expectation is placed on the technology of adopting closed section die-cast parts and of superplastic forming.