Mazak HTC-400 Spindle Repair

The Mazak HTC-400 is a large CNC horizontal machining center.  It comes standard with an oil mist lubricated and coupling driven spindle capable of running up to 10,000 rpm.

CHALLENGE

The bearings of this Mazak HTC-400 spindle were very noisy when rotated by hand incoming. The residual lubrication oil in the spindle was thick and contaminated, and the inside of the front cover was full of coolant residue and chips. All of the bearings felt worn when rotated, especially the #4 rear bearing. The tooling taper ID was damaged and bell-mouthed with runout >20µ. The integrated drive dogs were worn. The drive coupling was stuck on the shaft and the keys, key ways, and t-bar slot were worn.

SOLUTION

The following actions were performed on this Mazak HTC-400 spindle:

• Clean all parts of the spindle
• Replace all bearings, bolts, and o-rings
• Grind, plate, and finish grind the tooling taper ID
• Rework the drive dogs, keys, drive coupling key ways, and t-bar slot
• Advised our customer to check their spindle oil lubrication system for contamination and proper settings prior to reinstalling the spindle

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.