Haas Mini Mill Spindle Repair

The Haas Mini Mill is a compact 3-axis vertical machining center with a belt-driven, 6,000 RPM grease-lubricated spindle.  The machine is designed for small spaces such as schools, shops just starting up, or as a secondary operation machine for a larger shop.

CHALLENGE

The customer had called to let us know that his Haas Mini Mill spindle was getting excessively hot and that there was a good amount of bearing noise while running.  Upon arrival to Northland Tool and Electronics, the spindle was very difficult to spin by hand which matched the symptoms the customer was experiencing.  After breaking down the spindle, it was found that the bearings were contaminated and the inside of the housing was filled with rust.  The critical dimensions were then measured(bearing journals, bearing shoulders, housings, and taper).  The front and rear bearing shoulders were found to have 15μm of runout and showed signs of significant wear.  No other significant dimensional deviations were noted and the spindle moved on to the next stage.

SOLUTION

The following actions were performed on this Haas Mini Mill spindle repair:

• Thoroughly clean all parts of the spindle
• Replace all bolts, o-rings, bearings, and bellevilles
• Kiss grind the front and rear bearing shoulders to correct runout

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.