According to a recent survey, a shocking 30% of U.S. industrial companies reported experiencing a lubricant-related gearbox failure within the last year. With so many moving and rotating parts, a gearbox is highly susceptible to breaking down without the proper lubrication; if your lubricant is contaminated, its interaction with the intermeshing surfaces only increases wear, corrosion, and the potential for a catastrophic breakdown. Thankfully, most gearbox failures can be avoided by taking a proactive maintenance approach, helping manufacturers steer clear of these problems before they even occur.
When it comes to contamination control, proactive maintenance is the best solution simply because proactive maintenance combines the principles of both preventative and predictive maintenance by focusing on the source of equipment failure – which, in this case, is contamination. If you can prevent contamination from happening in the first place, you can keep wear rates at a minimum, as long as you’re using the right lubricant for your operating conditions. Keeping your gearbox contaminant-free in addition to using the proper lubricant (and monitoring the health of that lubricant) can greatly contribute to the overall health of your machine, and also help reduce your plant’s maintenance costs.
What Causes Contamination?Contamination can be defined as any foreign body or matter that infiltrates the system and causes harm to the gearbox, substantially reduces its effectiveness, or adversely affects operation. Some common examples of contaminants include hard particles, environmental dirt, moisture, heat, process chemicals, the incorrect lubricant, the incorrect lubricant grade, and other physical matter from the environment.
Most contaminants enter the gearbox through openings in the seals and breathers, but they can also get inside during routine top-ups, draining and refilling, and other maintenance to the unit. The rate at which contaminants enter the gearbox is dependent on the contaminant type, as well as the machine’s operating conditions and greater operating environment. In wet or humid conditions, the likelihood of moisture entering the gearbox significantly increases, but the likelihood of dust and other debris entering is reduced. In dry conditions, the likelihood of dust and hard particles entering the gearbox is greatly increased, but the likelihood of moisture entering is much less. Likewise, if your machine is in an environment with lots of airborne contaminants (e.g., coal dust in a coal mine), you’ll be at a greater risk for contamination.
How Do You Prevent Gearbox Contamination?
An old industry rule of thumb says that it costs 10 times more to remove a contaminant than it does to exclude it. Unless you want to pay for costly repairs down the road, we suggest following these preventive procedures:
Seals and Breathers
The standard lip seals on most gearboxes are inexpensive and need to be replaced frequently. In good condition, they do an adequate job of preventing oil leakage and contaminants from entering; however, their effectiveness pales in comparison to that of labyrinth seals. Though labyrinth seals are more costly than standard options, their added durability and contaminant prevention provides a better long-term value.
Nearly all gearboxes have an exhaust tube for breathing. And while newer models come with a vent plug, the majority of these vent plugs aren’t capable of stopping small particles from entering the gearbox. Allowing only clean, dry air to enter the system is one of the best measures to prevent contamination. To help maximize contaminant prevention, you should install a high-quality desiccant breather to remove as many airborne particles as possible. These breathers absorb water and filter particulate contaminants from the atmosphere before they enter your fluid system, preventing moisture contamination and providing particle filtration up to 2 microns.
Drum Pump Filtration and Dispensing Systems
Actively filtering lubricants from storage drums can prevent contamination-related problems. By using a drum pump filtration system like the one pictured below, you can help reduce particle contamination, filter out existing physical contamination, and eliminate messy spills.
Sampling ports (valves) are designed to draw lubricant samples from industrial equipment to give manufacturers a better indication of the lubricant quality during operating conditions. These ports provide quick and accurate samples to help you catch any contaminations before they can wreak havoc on your gearbox, and regularly collecting and analyzing these samples is an essential part of a preventative maintenance program. Sampling ports also make for a more repeatable and representative sampling location within the sump by providing the ability to sample from the “work zone” of the fluid, in addition to providing a sample from the same location consistently.
Oil Analysis and Gearbox Filtration
A proactive maintenance approach to contamination addresses predictive maintenance activities in addition to the preventative procedures we just covered. Despite taking the proper steps to prevent gearbox contamination, it’s important that you don’t stop analyzing your oil just because you’ve implemented a few preventative maintenance procedures. Predictive maintenance strategies use techniques that detect the early warning signs of failure by monitoring oil and machine health. Regular oil analysis is an important part of any proactive and/or predictive maintenance plan, because in order to prevent contaminated oil from causing damage, you need to know when the oil’s health is degrading or needs attention. This means checking for the right viscosity, ensuring you have the necessary additives for the application, and taking the proper steps to keep the lubricant clean and up to spec. In fact, there are three main things you should look for during your oil analysis tests:
- Oil Health – These tests analyze the physical properties of the oil (e.g., viscosity, acid number) to determine whether the oil is suitable for use, or ready for a change. If the oil doesn’t have the proper physical properties, it will accelerate the wear rate of your machinery.
- Contaminants – Contaminants from your machine’s surrounding environment (e.g., dirt, water, debris, etc.) are the leading cause of premature machine degradation and failure. Frequently monitoring contaminant levels will help you prolong the life of your machinery.
- Machine Health – Contaminated oil leads to increased machine wear, which means wear particles are generated at an exponential rate when running your machine. By regularly testing for these wear particles in your oil, however, you can determine which parts of your machine are in need of maintenance, and you can replace worn-out components before they cause further damage or a major shutdown.
Performing Oil Analysis Tests
Now that you know what to look for, it’s time to explain how to look for it. Make sure you follow the three steps below when conducting your oil analysis tests:
Step 1: Set Oil Cleanliness Benchmarks
While it’s difficult to settle on the “magic number” you’ll use to determine whether or not your oil is suitable for use, you need to establish the point at which your oil needs to be replaced. Thankfully, the American Gear Manufacturers Association (AGMA) partnered with the American Wind Energy Association (AWEA) to create some general standards for lubricant cleanliness in wind turbine gearboxes – which can be applied to many different applications. Use their standards below as a good benchmark for your own lubricant cleanliness.
Step 2: Reach Those Benchmarks!
In order to reach your benchmarks, there are two things you must do: stop contaminants from entering the gearbox and improve filtration.
- In addition to using the preventative products described above, make sure your oils are kept in a clean, dry location, and don’t mix oils of an unknown origin.
- New oils should be added to the gearbox via a fine filter (i.e., 3 microns), and make sure you use extra caution not to introduce any contaminants during maintenance.
- Use filters to quickly remove any particles and water from your oil, as they can lower your oil consumption and extend your gearbox and bearing life. A well-designed contamination control system will use both inline and offline filters to provide maximum cleanliness.
- Using quick disconnects with pumps and filters or using designated Spectrum filling containers can aide greatly in reducing the amount of contaminants entering the system.
Step 3: Maintain Oil Cleanliness
Now that you’ve set the standard and implemented the proper preventative procedures, it’s time to make sure that you stay at these levels. Schedule regular oil analysis tests with your machines, and make sure you take action when your cleanliness goals aren’t being met. If you can remove contaminated oil from your system before it does too much damage, you can save yourself lots of time, money, and hassle down the road.
Talk to U.S. Lubricants
Though these contamination prevention systems and predictive techniques might have a higher upfront cost, their long-term value for preventing wear, breakdowns, and repairs is certainly worth the extra expenditure. Don’t become a part of that gearbox failure statistic because you didn’t heed the warnings. Using the proper lubricant and following a proactive contamination maintenance plan is the best way to prevent gearbox wear and avoid costly breakdowns. To learn more about the contamination prevention systems and oil analysis services U.S. Lubricants offers, please contact Tony Springer at TSpringer@uslube.com or by phone at (800) 490-4900 ext. 8823.