Southeast Paper Mill Avoids Year of Downtime with OTC Rebuild

Overview

A major paper mill in the Southeast United States experienced the sudden failure of its most critical asset: a 1,000 HP medium-voltage induction motor weighing 12,500 pounds. This motor was essential to the mill’s production line, and its failure created an immediate risk to plant output. With a relationship spanning more than 20 years, the paper mill asked OTC Industrial Technologies to step in and provide a solution.

Challenge

The failure was caused when the front bearing seized while the motor was running. The resulting heat and friction welded the bearing to the shaft, and the bearing cap fused in place. As the damage progressed, both the inner and outer races spun freely, destroying the shaft and front-end housing. During disassembly, the bearing cap shattered and left the motor inoperable.

The mill installed a smaller 600 HP motor to maintain partial operation. This stopgap solution allowed production to continue, but only at 60% of normal capacity. Since output was reduced by 40%, it created significant strain on operations. A new replacement motor was quoted at a 6–12-month lead time, which was not viable for the customer’s production needs.

The situation was further complicated by the absence of documentation and spare parts. No technical drawings of the motor were available, and replacement components would have carried lead times comparable to ordering a completely new unit. This meant that even piecemeal repairs from ordered parts would not resolve the downtime challenge in a reasonable timeframe.

A root cause investigation determined that improper lubrication practices led to the failure. Grease added through long tubes during routine maintenance never reached the bearing cavities. The bearings contained only the original factory grease, which eventually failed, leading directly to bearing seizure and catastrophic motor damage. The customer needed a motor repair solution, and fast.

Solution

After contacting OTC, the OTC team determined that the best path forward was a complete in-house rebuild of the damaged motor. Leveraging its long-standing experience in industrial motor repair, the OTC team began with a complete teardown. The customer was invited to observe this stage so they could see the extent of the damage firsthand and better understand the analysis that identified poor lubrication as the cause of failure. This transparency also gave their maintenance team immediate guidance on how to prevent similar issues in the future.

Once disassembly was complete, attention turned to the motor’s most critical damaged components. The shaft, bearing cap, and shaft grounding device were carefully measured and reverse-engineered to match the original specifications. Because the shaft was severely compromised, significant material had to be cut away. The OTC team then rebuilt it using weld build-up, straightened it in a large-capacity lathe, and machined it back to precise tolerances.

With the core components restored, OTC upgraded the supporting systems. The lubrication system was redesigned so grease could be delivered properly to the bearings, addressing the root cause of the failure. At the same time, the grounding system was rebuilt and enhanced to protect the bearings from electrical discharge, improving long-term reliability.

The motor was fully reconditioned with cleaning, dip-and-bake processing, and a series of dynamic checks: rotor bar testing, vibration analysis, and surge testing. These steps showcased OTC’s ability to deliver comprehensive motor rebuild services that quickly restored both performance and reliability.

By choosing to rebuild instead of replacing, the customer avoided the lengthy motor repair turnaround time tied to sourcing new equipment or waiting for parts. Instead of a 6–12-month outage, the project was completed in just weeks.

The 1,000 HP motor as it arrived: dirty, damaged, and inoperable.

The motor shaft is lathed during weld build-up and final machining, restored to factory specifications with precision tools.

Interchangeable tooling was used to drill, center, and support the shaft, ensuring accuracy throughout the rebuild process.

Results

The rebuilt motor was shipped, reinstalled, and brought online with OTC providing startup support. Production returned to 100%, eliminating the 40% shortfall caused by the temporary motor.

What could have been nearly a year of lost production was reduced to a matter of weeks. The repair allowed the mill to avoid motor downtime and quickly restore production capacity, proving the value of choosing a rebuild over replacement. The customer praised the project as both exceptionally executed and technically precise.

Upgraded lubrication and grounding systems, combined with OTC’s ongoing support, will reduce the risk of repeat failures going forward.

For expert motor service and repair, contact OTC to get you back up and running fast.