Steel Worm gear shafts used in worm gearbox worm wheel gear screw
1) Forging 8620 raw material into bar
2) Pre-Heat Treat Normalizing or Quenching
3) Lathe Turning for rough dimensions
4) Hobbing the spline below video you could check how to hob the spline
5) https://youtube.com/shorts/80o4spaWRUk
6) Carburizing heat treatment
7) Testing