Posted February 22, 2016 - Updated Dec 4, 2019
(Engineering Bulletin #/web911)
For customers who do their own end machining, it may be necessary to anneal (soften) the ends of the ball screw shaft.
Annealing the Shafting
For short shafts, immerse the portion of the screw, which is to remain hard in water. Heat the remaining portion of the shaft to approximately 1200° F. You can measure this temperature or just look for a dark red color. Allow the part to air cool – Do Not Quench. Check the hardness with a file. If the shaft is still too hard, repeat the process. Heating can be done with a flame or by induction. Heat evenly to avoid warpage by spinning the shaft or moving the heating implement.
For longer shafts, make a heat barrier of water-soaked rags between the portion to be annealed and the portion to remain hard. Heat the portion to be annealed as above.
Caution: Annealing the screw sections over which the ball nut will operate will result in premature failure of the ball nut and/or ball screw shaft.
Warning: Heat-treating can be dangerous and can result in personnel injury. Always wear eye protection and use other necessary and adequate safeguards to prevent fire and personal injury.