Axle

High-speed rail axles are safety-critical components that need a through-hole running the full length. The hole allows an ultrasonic probe to pass through the axle for non-destructive inspection. Without the through-hole, internal defects cannot be detected. In my experience, the drilling quality directly determines whether the axle passes its final ultrasonic inspection. Axle Specifications and Material Grades A high-speed rail axle is typically 2-3 meters long with a 30-60mm bore. The material is high-strength axle steel like EA1N or EA4T. The surface finish requirement is Ra 1.6um as-drilled. The straightness spec is typically 0.5mm per meter. ...

Railway axles are one of the older applications of deep hole drilling. A locomotive or railcar axle needs a hole drilled through the center for two reasons: weight reduction and ultrasonic inspection access. The hole allows a probe to pass through the axle and check for internal defects. Without the through-hole, you cannot inspect the axle non-destructively. So every major rail axle gets drilled. I have worked on axles for freight cars, passenger cars, and locomotives. They range from about 1.5 meters to 3 meters long, with a bore diameter of 25mm to 60mm. ...