Spindle Housing

Spindle Housing

Flange Housing Flange

The housing flange is typically a ring attached to the OD of the spindle housing. It is used to locate the spindle in the machine tool and usually has holes bored into it for the mounting bolts. The mating surface of the flange needs to be perpendicular to the spindle centerline. The mounting surface must also be burr free to avoid misalignment during spindle installation.


Housing Bearing Shoulder
The housing bearing shoulder contacts the bearing outer race and locates it parallel to the shaft centerline. It is critical that the housing bearing shoulder is perpendicular to the shaft centerline and has no run out.

If the housing bearing shoulder is not held to micron tolerances the following can occur:

  • Misalignment between the inner and outer bearing race
  • Point loading on the outer race
  • Improper preload of the bearings
  • Vibration during spindle use
  • Poor part finish
  • Poor spindle life

Every housing bearing shoulder is checked in our spindle evaluation. If our evaluation finds them to be out of tolerance they can be easily fixed in our grinding department. Many other spindle repair companies do not have in house spindle grinding departments so this step of the rebuilding process is often overlooked by them. This results in poor spindle performance and reduced spindle life.

Bore Housing Bearing Bore

This is the location on the stationary housing that the bearing seats. It is extremely important to have the housing bearing bore within micron tolerances for size, parallel to the housing centerline, perpendicular to the bearing shoulder and concentric to the other housing bores in the assembly.

Spindle manufacturers have realized that by changing the characteristics of the bearing shaft and housing fit tolerance they can manipulate the clearances in the bearings. This allows spindle manufacturers to manipulate spindle speeds and load capacities. As a spindle rebuilder we document the methods each spindle OEM is using on each model that they manufacture. This gives us a comprehensive guide for the tolerances our grinding room needs to meet. Many spindle repair companies either do not grasp this concept or use outside vendors for their grind plate grind work and these important tolerances are not achieved. This definitely causes shorter spindle life and poor spindle performance.