As there are many wear parts in the bogie of freight car, the cost of maintenance is high. Also there are many problems to change the wear plates. In case of welded structure bogie, wear plates are attached 30 positions. Especially, the occurrence of the wear quantity at the side of axle box is higher than any other wear plates. Wear parts needs the low wear and high strength. But the repeated load of carbody has acted on wear parts up down direction continually, the friction force defects at their surfaces. At present, the life of wear plates at the side of axle box is about 3~4 years. So we need the new development of wear plate over ten years life to improve the durability and find the new composite material for maintenance free.