Receipt & Evaluation

Eitzenberger manufactures precision air bearing spindles used in fine machining, optics turning, glass milling, grinding and polishing of optical lenses and displays for cell phones and tablets, and micro-machining of optical and medical products. They have a well-earned reputation for accuracy and reliability.

This unit arrived at our facility in heavily worn condition. Visual and functional inspection revealed multiple areas of concern:

• External corrosion and oxidation across the motor housing and spindle body
• Evidence of coolant and moisture ingress, particularly around fittings and seams
• Contamination buildup indicating prolonged operation in a harsh environment
• Bad encoder signal
• Potential degradation of internal components, including bearings and sealing systems
• Visible wear at the spindle nose and tooling interface, suggesting possible accuracy and runout issues

The overall condition indicated that this unit had been operating well beyond optimal service intervals, with a high likelihood of internal damage affecting performance and reliability.

Disassembly & Component Evaluation

Following complete disassembly, each component was individually inspected, tested, and measured against OEM specifications.

A key example is the stator assembly. Despite the harsh external condition, the stator passed all electrical and insulation testing. The windings and connections remained intact and within acceptable tolerance, allowing us to retain and reintegrate the original stator.

Other findings during teardown included:

• Contaminated, worn or damaged axial and radial bearings
• Seal degradation
• Corrosion affecting non-protected surfaces
• Excessive runout measured at critical precision interfaces
• Failed encoder
• Drawbar and actuator failure

Bearing Damage & Drawbar Inspection

The outer thrust bearing showed clear signs of wear tracking and surface degradation where the shaft had seized against it, along with material breakdown along the bearing raceway. These conditions directly affect axial load capacity, rotational stability, and overall spindle accuracy — especially critical where micron-level precision is required.

The drawbar assembly is critical for proper tool retention and clamping force and can impact shaft runout. We inspected it for:

• Wear, galling, and surface fatigue
• Belleville washers (spring stack) checked for load consistency and fatigue
• Clamping force and repeatability
• All functional elements restored or replaced as required

Any inconsistency in this system can lead to tool holding instability, reduced accuracy, and premature wear of tool interfaces. Our process ensures the drawbar system is restored to deliver consistent, reliable clamping force under operating conditions. We replace all seals, O-rings, and Belleville washers with new, and repair associated threads and wear surfaces as needed.

Heidenhain Encoder Testing

The Heidenhain encoder is a critical component of the spindle system, responsible for providing precise feedback on rotational position and speed. This information is essential for accurate spindle speed control, synchronization with machine axes, and maintaining precision during operation.

In lens grinding applications, where tolerances are extremely tight, even minor inaccuracies in encoder feedback can lead to dimensional errors, surface finish inconsistencies, and process instability. The encoder ensures the machine knows exactly what the spindle is doing at all times.

Final Result

Following complete restoration, this Eitzenberger spindle was returned to like-new condition, both functionally and cosmetically.

All critical systems — including bearings, sealing, drawbar operation, and encoder feedback — were validated to ensure reliable performance. Precision components such as the shaft and stator were preserved where appropriate, while worn elements were replaced or restored to meet OEM specifications.