Robodrill Spindle Repair

The Fanuc Robodrill is a compact CNC vertical machining center made for high production work.  It comes equipped with a grease lubricated and coupling driven spindle capable of running up to 24,000 rpm.

CHALLENGE

Our customer has a large complement of high-speed vertical machining centers which are used to produce job shop parts orders for their customers, as well as for mold making in support of their in-house injection molding facility. They contacted us while they were in the process of replacing a bad motor in one of their 24,000 rpm Fanuc Robodrill machines. They felt that the spindle bearings were suspect as well, and asked us to evaluate the spindle in our facility. We found that the bearing grease was not particularly contaminated, and that the rear pair of hybrid ceramic bearings had significantly more wear than the front pair. This led us to the conclusion that vibration and shaft runout of the motor had caused the rear bearings in the direct-coupled spindle to repeatedly load and unload, causing premature deterioration.

SOLUTION

As we found no significant dimensional deviations of the tooling taper, shaft journals and shoulders, or in the housing bores, our solution was a “straight” repair of the spindle. We rebuilt the spindle with all new ceramic bearings, gripper force balls, o-rings and assembly screws.

RESULT

After reassembly of all components, adjusting bearing preload, and undergoing break-in and testing procedures, this spindle passed our final quality inspection before being returned to our customer with a 1-year warranty.