Feed-Axis

The ball screw drives the feed axis on a deep hole drilling machine. It converts motor rotation into linear movement of the spindle carrier or workpiece. A worn ball screw causes inconsistent feed rate and poor hole quality. I have replaced enough ball screws to know that preventive maintenance is far cheaper than dealing with a failure during production. Ball Screw Inspection and Condition Assessment I check ball screw condition by measuring the backlash annually. Backlash is the play between the ball nut and the screw, and it indicates wear in the recirculating ball tracks. The measurement procedure is straightforward but requires careful technique to get consistent readings. ...

Hydraulic cylinder drift on deep hole drilling machines causes the feed axis to move when it should stay in position. This drift can advance the drill into the bore when it should be retracting, causing tool damage, or it can let the spindle head sag during a tool change, making alignment impossible. I have debugged drift problems on machines ranging from small gun drills to large BTA systems with 10-ton feed forces. ...