askawa USAIKM-50-BK33-C Spindle Motor – Water Damage to the UTMSI-10AAEAZM Encoder Successfully Repaired

04.05.2025 by Viktor Siebert

askawa USAIKM-50-BK33-C Spindle Motor – Water Damage to the UTMSI-10AAEAZM Encoder Successfully Repaired

Unexpected machine downtime results in significant costs for many manufacturing companies. It becomes particularly critical when older machine tools are equipped with discontinued components and original spare parts are no longer available. This was exactly the situation faced by a manufacturing company from Hungary that contacted us.

Several water-cooled Yaskawa USAIKM-50-BK33-C spindle motors are installed in the company’s CNC machining centers and operate continuously in a three-shift production environment. One of these motors failed during production due to an encoder fault. Since the original UTMSI-10AAEAZM encoder is no longer available, replacing the complete spindle initially appeared to be the only possible solution.

After consulting with our team, the customer decided to have the motor repaired by us.

Incoming Inspection and Initial Diagnosis

After the motor arrived at our facility, it first underwent a thorough visual inspection.

During the initial examination, clear signs of water ingress inside the motor were discovered. Moisture traces and the first signs of corrosion were visible around the encoder area. The bearings also showed noticeably rough operation compared to their normal condition.

One particularly noticeable finding was the buildup of deposits inside the drainage system.

Based on our many years of workshop experience, this is a damage pattern we know very well.

Root Cause Analysis

The Yaskawa USAIKM-50-BK33-C is equipped with a water-cooling system incorporating an integrated drainage system. This system is designed to safely remove condensation or small amounts of coolant that may enter the motor housing.

However, after many years of operation, deposits can accumulate within the drainage system.

As a result, water can no longer drain properly and begins collecting inside the motor.

Typical consequences include:

Corrosion in the encoder area
Damage to the precision bearings
Moisture entering the encoder
Failure of the UTMSI-10AAEAZM encoder
Increased spindle running noise
Higher vibration levels at elevated spindle speeds

From our experience, this failure pattern is one of the most common causes of failure in water-cooled USAIKM spindle motors.

The Challenge of the UTMSI-10AAEAZM Encoder

One of the biggest challenges during this repair was the fact that the original UTMSI-10AAEAZM encoder is no longer available from the manufacturer.

Many machine operators therefore face the problem that an otherwise technically sound spindle motor must be taken out of service simply because a replacement encoder can no longer be obtained.

Since we have been repairing these motors for almost ten years, we have developed our own technical solution.

Our newly developed encoder system replaces the original encoder and allows these spindle motors to be professionally repaired even today.

This enables many machines to remain in operation economically despite the lack of original spare parts.

Our Repair Process

After the diagnostic process was completed, the motor was completely disassembled.

As part of the complete overhaul, the following work was carried out:

Complete disassembly of the motor
Thorough cleaning of all assemblies
Cleaning of the complete drainage system
Inspection of the water-cooling system
Replacement of worn seals
Replacement of damaged precision bearings with suitable hybrid bearings
Complete overhaul of the cooling fan
Installation of our newly developed encoder system
Inspection of all mechanical fits
Final assembly according to workshop standards

All repair work was fully documented.

Final Testing

After reassembly, the motor underwent a complete functional test on our test bench.

The following items were inspected:

Smooth motor operation
Encoder functionality
Bearing noise
Mechanical runout
Temperature behaviour
Vibration behaviour at different operating speeds

Only after successfully passing all tests was the motor approved for return shipment.

Customer Feedback

After reinstalling the motor, we received the following feedback from the customer:

“The motor is running perfectly again. Since the repair, the machine has been operating reliably in daily production. We were particularly impressed that such a professional repair solution was possible despite the original spare parts no longer being available.”

Feedback like this confirms our daily work and demonstrates that even older spindle motors can often be repaired economically.

Technical Data for the Yaskawa USAIKM-50-BK33-C Spindle Motor

Motor Highlights at a Glance

Series: Yaskawa USAIKM
Continuous Power: 6 kW
Operating Voltage: UVW ~200 V AC
Rated Current: 65 A
Torque: 11.5 Nm
Max. Speed: up to 12,000 RPM (depending on version)
Cooling: Liquid cooling with drainage system
Shaft Diameter: 28 mm
Weight 34,6 KG
Encoder: UTMSI-10AAEAZM, 1024 pulses/rev

Technical Information about the Yaskawa USAIKM-50-BK33-C

Feature	Information
Manufacturer	Yaskawa
Model	USAIKM-50-BK33-C
Motor Type	Water-cooled CNC spindle motor
Cooling	Water cooling with integrated drainage system
Encoder	UTMSI-10AAEAZM
Bearings	High-speed precision bearings
Special Feature	Original encoder discontinued

Typical Applications

Spindle motors of the USAIKM series are primarily used in CNC machine tools and are commonly installed in machining centers requiring high spindle speeds and precise spindle control.

Maintenance Recommendation

Based on our workshop experience, we recommend regularly inspecting and cleaning the drainage system, especially on water-cooled spindle motors.

Even small deposits can restrict water drainage and eventually lead to severe damage to both the bearings and the encoder.

Regular preventive maintenance significantly extends the service life of these high-quality spindle motors and helps avoid unexpected production downtime.

Conclusion

The Yaskawa USAIKM-50-BK33-C remains a highly capable spindle motor for machine tool applications. Despite the age of many machines and the limited availability of original spare parts, defective motors do not necessarily have to be replaced.

Thanks to our many years of experience with the USAIKM series, the overhaul of mechanical assemblies, and our in-house developed replacement solution for the discontinued UTMSI-10AAEAZM encoder, we are able to successfully repair many of these spindle motors and return them to reliable production service.hs
+ Seal replacement during major maintenance intervals