The Bridgeport Torq-Cut 22 is a smaller CNC vertical machining center. It comes fitted with a grease lubricated and belt driven spindle capable of running up to 7,500 rpm.
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Porta N-145 FMU Spindle Repair
The Porta N-145 FMU spindle is one of several installed on a transfer machine used in the manufacturing of driveline components. It is a grease lubricated and belt driven spindle capable of running up to 2,000 rpm.
CHALLENGE
The bearings in this spindle were very noisy when rotated in assembly incoming. Upon disassembly we observed that the entire spindle interior was heavily contaminated with a brown sludge consisting of part coolant and particulate. This contaminant had degraded the grease in the bearings and caused wear of the races and rotating elements. We also noted degradation of the ball screw unit which controls the Z axis motion. Finally, we decided to address the heavily damaged and stuck tool drive keys and the tooling taper ID which was extremely worn, with runout >46µm. The customer retained the drawbar assembly, reinstalling it in their spare spindle to keep production moving.
SOLUTION
In preparation for the final assembly of the spindle, we sent the ball screw unit to a reliable vendor for a precision rebuild. We completed a grind, chrome plate, and finish grind of the tooling taper ID on our in-house Kellenberger grinding machines. We also machined out the old drive keys and fabricated a new set. After a thorough cleaning of all components, we rebuilt the spindle with all new bearings, drive belt, seals, o-rings, and assembly screws. We also installed the rebuilt ball screw unit and the newly-fabricated drive keys.
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.
DETAILED CAUSE OF FAILURE
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More Case Studies
Repair History - Here are examples of similar spindle repairs that may contain additional information that will help you. If you have additional questions, please contact us.
OD grinding — or outside diameter grinding — is a cornerstone of precision manufacturing, where exact specifications and flawless surface finishes are essential.
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