Case Study
From Routine Leak Repair to Long-Term Reliability at Arizona Copper Mill
Application: Gearbox
At copper processing facility, persistent oil leakage from a critical gearbox had become a familiar part of daily operations. The issue was not new. Oil loss, frequent seal replacement, and ongoing maintenance intervention had been occurring for years. Like many facilities, the operation had come to view gearbox leaks as an unavoidable cost of doing business rather than a solvable reliability problem.
The gearbox relied on traditional contact lip seals to retain lubrication. While inexpensive, these seals wore rapidly due to constant shaft contact, which often led to grooving, lubrication loss, and contamination ingress. As a result, seals required replacement every 3 to 6 weeks. Each replacement demanded scheduled downtime, several maintenance personnel, and 3-4 hours of labor in a confined and difficult‑to‑access location.
Between scheduled maintenance events, the leaking gearbox created additional challenges. Oil loss increased lubricant consumption, created housekeeping and slip hazards, and introduced environmental and safety concerns. Operators were required to top off oil every shift simply to keep the gearbox operational.
Rethinking the Problem
For decades, leaking gearboxes have been tolerated across heavy industry. When leaks are frequent, they often are reclassified as “preventive maintenance” rather than recognized as indicators of an underlying design problem. However, replacing the same seal every few weeks is not prevention.
As safety expectations increase, environmental regulations tighten, and maintenance budgets come under greater scrutiny, organizations are re‑examining long‑accepted practices. They are shifting from a stop-the-leak mindset to seeking a permanent solution focused on reliability, reduced maintenance burden, and long‑term cost savings.
Solving the Challenge
High oil levels and oil splash make gearboxes notoriously difficult to seal, especially in industrial rotating applications. In this application, the challenge was further compounded by a flooded bearing housing condition.
Unlike typical splash‑lubricated gearboxes, this system actively pumped oil through the bearings to ensure continuous lubrication. While effective for bearing life, this design increased oil pressure at the seal location. Oil returning to the sump was restricted, creating an operational flood that overwhelmed traditional lip seals and accelerated failure.
The new sealing solution needed to operate reliably in a flooded environment, retain lubrication without shaft contact, prevent contaminent ingress, and be installed on-site without decoupling equipment.
Eliminate Leakage with a Bearing Isolator
Inpro/Seal’s non-contacting, labyrinth-style bearing isolator was selected as the foundation for the solution. The design captures oil attempting to exit the housing and returns it to the sump through an engineered drain path, while centrifugal force expels external contaminants away from the bearing cavity.
To address this appllication’s unique operating conditions, the standard design was custom engineered to include:
- A split configuration to allow seal installation without decoupling equipment
- A larger D Groove to capture the volume of oil flowing through the system
- An external drain and revamped system to return oil to the sump
This approach transformed sealing from a replaceable component into a system‑level reliability upgrade.
A Return on Investment
By eliminating seal wear and restoring proper oil management, the customized bearing isolator provided a true permanent sealing solution. The results extended well beyond stopping leaks:
- Maintenance frequency was dramatically reduced, freeing labor for higher‑value tasks
- Unplanned downtime decreased, increasing available production time
- Lubricant consumption dropped, reducing operating costs and environmental exposure
- Safety improved, eliminating oil‑related slip hazards and cleanup activities
Inpro/Seal’s custom-engineering expertise was the key to designing the permanent sealing solution. After more than two years of continuous operation, the gearbox remained leak‑free with no signs of degradation or performance loss.
Advantages of Bearing Isolator Installed on a Sag Mill Gearbox
- Custom engineered to provide permanent bearing protection.
- Uses a split design for installation without decoupling the equipment.
- Utilizes an external drain and revamped oil return system to accommodate an operational flood in the bearing housing.
- Increases production, decreases maintenance costs, and provides a safer working environment.
Ready to Get Started?
Count on us to improve equipment reliability through permanent bearing protection. No matter the size or complexity of the application, Inpro/Seal’s technical experts can design a custom solution for your equipment. With over 40 years of experience, we are the trusted source of Bearing Isolator technology.
