Abstract
Austempered Ductile Iron (ADI), which has much the same strength and toughness as usual steels, has been developed. ADI has many advantages in mechanical properties and manufacturing, such as weight reduction, good properties of vibration and noise, low cost in machining and heat treatment of blanks due to near-net-shape casting. Using these advantages, it has been reported that ADI can be sufficiently applied as a medium hardness gear material. In addition, it is important to reduce the amount of the lubricant when many problems, i.e. global environment, resource conservation and cost reduction, etc., are considered. So it is necessary to examine the performance of ADI under oil-free condition or Minimal Quantity Lubrication (MQL) condition. In this paper, MQL condition is investigated using a disk machine which simulates the rolling and sliding action of gears. Then the surface failure strength of ADI gears under spray MQL condition is examined using a power-circulating type gear testing machine in comparison with steel gears which have almost the same hardness of ADI. As the results of experiments, the surface failure strength of ADI gears under MQL condition is larger than that of SCM435 gears.
