How a train wheel is made

Trains running mile after mile put high demands on their wheels.  Meeting their requirements  on dimensional tolerances and surface quality is essential  both as a matter of safety  but also in terms of comfort for the passenger.  Producing finished wheels involves a manufacturing chain  including different forming processes  metal cutting and testing.  Blanks are heated in a rotary kiln before compression forged. 

The centre is then punched out and the profile is rollformed.  A bending process gives the wheel its final shape  and then the wheel rim is chilled in water  thus hardening it.  Finally the wheel's mechanical properties are tested  to ensure the wheel is ready for further machining.  To achieve required dimensions and surface quality  the hub web and rim on the wheel are machined. 

Round inserts are combined with over and under coolant  for best performance and chip evacuation.  Non-destructive testing ensures the wheel surface meets the requirements  on quality and tolerances.  Then it's mounted on the axis installed on the train  and ready for use. 

After a period on the tracks  wheels need re-turning.  The train rolls into the machine shop  where every flat spot flange deformation  and crack is removed.  Until the wheels are reset to their former standard  ready for another cycle...