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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Johnford DMC 2100H Spindle Repair
The Johnford DMC 2100H is a larger CNC bridge mill. This machine comes equipped with a grease lubricated and pulley driven spindle capable of running up to 6,000 rpm.
CHALLENGE
When this Johnford DMC 2100H spindle arrived at Northland Tool and Electronics we completed a full breakdown and evaluation. Upon inspection, we found that there was fretting on the shaft OD from the #3 bearing location back to the end. The nut loading the quad set and locating ring was tight, but the nut for the pulley and tail support bearings was loose. We then measured the critical dimensions (bearing journals, housing, taper, etc.) and found a few unacceptable deviations. First the shaft tail had 145µ runout in assembly, likely the source of fretting. Second, the shaft taper had poor contact with an 8-12µ window at the mouth.
SOLUTION
The following actions were performed on this Johnford DMC 2100H spindle:
- Clean, inspect overall dimensions
- Kiss grind shaft taper
- Kiss grind shoulders on seal cover, labyrinth ring, bearing spacers, locating ring & pulley to reduce tail runout
- Replace bearings, screws, and o-rings
- Upgrade tail support bearings to appropriate speed rating
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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