Hydrostatic Spindle Repair & Rebuilding

Powered by an external hydraulic system, a hydrostatic spindle shaft is guided by static oil pressure generated within the oil pockets of the glide elements. Hydrostatic spindle design is based upon the principle of fluid friction, in which the bearing load capacity is created by the shaft rotation.

By comparison, hydrodynamic spindles rely on the speed of the journal rotation to create pressure in the fluid between the faces.

Hydrostatic and hydrodynamic spindles are often used in applications that incorporate ultra-high rotational accuracy with ultra-high vibration resistance.

Hydrostatic and hydrodynamic spindles are used in precision machining applications that require ultra-high radial accuracy, as well as when extremely high surface quality is desired.

Hydrostatic and hydrodynamic spindles deliver the following additional benefits:

• Long life (both of the spindle and cutting tool)
• Minimal to no wear
• Ultra-high precision grinding of brittle materials
• No friction at low velocity
• Thermal stability (lubricating oil removes heat)
• High damping coefficient
• High vibration suppression
• Repeatability

When a hydrostatic spindle fails it usually damages the bearing surfaces and shaft mating surfaces. To return the spindle to good working order, both surfaces need to be reconditioned or replaced then matched to each other, ensuring the gap is precisely aligned. This process requires high precision grinding equipment and a high level of skill that takes technicians years to acquire. Most spindle repair companies are not willing to make the investment in the equipment and training needed to perform these repairs.

Other hydrostatic spindle issues include potential oil leaks and metallic contamination in the lubricating oil, which accelerates component wear. Owners of hydrostatic or hydrodynamic spindles are advised to thoroughly clean the rest of their machine’s oil lubrication system to avoid recontamination of the spindle.

Total cost of a hydrostatic spindle repair is dependent upon a number of factors, including the amount of damage resulting from the failure and an assessment of lead time needed to achieve appropriately tight tolerances.

In general, hydrostatic and hydrodynamic spindle repairs are roughly 30% more expensive than spindles with steel or ceramic roller bearings.

Northland Tool & Electronics has repaired many different styles of hydrostatic and hydrodynamic spindles, from grinding machine wheel heads, to work heads, to centerless grinder wheel spindles. We have even worked on some spindles from milling applications that require extreme accuracy. Take a look at some examples below:

• Tschudin HTG 400 Spindle Repair
  The Tschudin HTG 400 is a hydrostatic grinding spindle capable of running up to 1,900 rpm.
• Studer S-20 Spindle Repair
  The Studer S-20 Hydrostatic grinder is belt driven and capable of running up to 910 rpm.
• Kellenburger Kel-vision URS125 Spindle Repair
  The Kellenburger Kel-vision URS125 is an OD wheelhead spindle. It is a hydrostatic spindle, belt driven, and capable of running up to 1,800 rpm.

If you have a damaged hydrostatic or hydrodynamic spindle, fill out this form to start the repair process. Once we receive your spindle, we will perform a full evaluation in order to diagnose the issue and provide you with an accurate price quote for repair.