How We Resolved Excessive Bearing Wear in a Paper Machine: A Practical Analysis and Solution
Excessive bearing wear in a paper machine was causing frequent downtime and high maintenance costs. We demonstrate how lubricant analysis and adjustments to the application process extended bearing lifespan by over 50%.
Photo: Isis França / Unsplash
In the paper industry, bearings are among the most stressed components of machinery. Their premature wear not only increases maintenance costs but can also lead to unplanned production downtime. In one of our cases, a customer was struggling with repeated bearing failures in the drying section of a paper machine, where temperatures reached up to 120 °C and high humidity impaired the effectiveness of the lubricant. After a detailed analysis of operating conditions and testing lubricant samples, we identified the key causes of the problem—and proposed a solution that significantly extended the service life of the bearings.
Problem: Excessive bearing wear and its causes
In the paper industry, bearings are among the most stressed components of machinery. In our case, the customer faced repeated premature bearing failures in the drying section of the paper machine, leading to unplanned downtime and high repair costs. Initial analysis showed that the cause was not mechanical damage but excessive wear due to a combination of high temperatures, contamination, and insufficient lubricating properties of the oil used.
Bearings in the drying section operate at temperatures often exceeding 120 °C, where conventional mineral oils lose their lubricating properties. Additionally, the presence of water vapor and paper dust worsened the situation—contaminants penetrated the lubricating film and accelerated abrasive wear. Standard oil analysis revealed an increased content of metal particles and a drop in viscosity, confirming that the lubricant could not maintain a stable protective layer between the friction surfaces.
Diagnostics: How we identified the key failure factors
To accurately identify the problem, we conducted a comprehensive diagnosis, which included analysis of the lubricant used, inspection of the bearings, and assessment of operating conditions. Oil samples were subjected to spectrometric analysis, which revealed a high content of iron, copper, and silicon—indicators of abrasive wear and contamination. Furthermore, we found that the oil viscosity had dropped by more than 20% compared to its original value, indicating degradation of the base oil due to high temperatures.
The bearing inspection confirmed the presence of microscopic scratches and pits on the rolling elements, typical of abrasive wear. We also found that the lubrication system was unable to effectively dissipate heat from the contact surfaces, leading to localised overheating. Based on these findings, we identified three main failure factors: insufficient thermal stability of the lubricant, inadequate protection against contamination, and unsuitable viscosity for the given operating conditions.
Photo: Geraldine Lewa / Unsplash
Solution: Selecting and applying the right lubricant
Based on diagnostics, we proposed switching to a synthetic polyalkylene glycol (PAG) oil with high thermal stability and excellent lubricating properties even at extreme temperatures. This type of oil maintains stable viscosity across a wide temperature range and resists oxidation better than mineral oils. To enhance protection against contamination, we recommended adding ester-based additives that improve the oil’s ability to form a strong lubricating film even in the presence of water and solid particles.
An important step was also optimizing lubricant change intervals and introducing regular oil condition monitoring through analyses. The customer began using a filtration system with a 5-micron rating, which effectively removed solid contaminants from the lubrication circuit. The viscosity of the new oil was selected to provide sufficient lubricating film thickness at an operating temperature of 120 °C without causing excessive friction during cold starts.
Results: Extended Bearing Lifespan and Reduced Costs
After implementing the new lubricant and adjusting maintenance procedures, significant improvements were observed. During the first six months of operation, we recorded a more than 60% reduction in bearing wear, confirmed by both oil analyses and visual inspections. The intervals between bearing replacements were extended from the original 3–4 months to over 12 months, significantly reducing maintenance costs and unplanned downtime.
Long-term monitoring showed that the new lubrication system not only extended bearing lifespan but also improved the machine's energy efficiency. Thanks to reduced friction, energy consumption decreased by approximately 5%, resulting in additional savings. This case clearly demonstrates how crucial the selection of the right lubricant and a systematic approach to maintenance are in demanding industrial applications, such as the paper industry.
Photo: Mike Hindle / Unsplash
Optimizing Lubrication Regimes: The Key to Wear Prevention
After changing the lubricant, we focused on adjusting the lubrication regime, which proved to be just as important as the quality of the lubricant itself. In the paper industry, bearings are exposed to extreme conditions – high temperatures, humidity, and mechanical stress. The standard lubrication intervals, originally set according to the machine manufacturer’s general recommendations, proved insufficient. We analyzed the operating conditions and found that bearings in critical nodes required more frequent lubricant replenishment, with intervals shortened by up to 40% compared to the original plan.
A key step was implementing an in-operation lubricant condition monitoring system. Through regular sample collection and analysis of metal particle content, viscosity, and water presence, we could precisely determine the optimal time for lubricant replenishment or replacement. This approach not only extended bearing lifespan but also reduced lubricant consumption by preventing premature degradation. In practice, this meant a 15–20% reduction in lubricant costs while simultaneously increasing machine reliability.
The Impact of Contamination and How to Prevent It
One of the surprising findings during diagnostics was that a significant cause of bearing wear was lubricant contamination by foreign particles and water. In paper production, this risk is particularly high due to the presence of cellulose, dust, and high humidity. Even small amounts of solid particles in the lubricant can cause abrasive wear, while water accelerates oxidation and reduces lubricant effectiveness. We therefore introduced several measures to minimize contamination.
The first step was improving the sealing of bearing units using special seals resistant to high temperatures and chemicals. We then installed filtration systems with a filtration fineness of 5 microns, which capture even microscopic particles. To remove water from the lubricant, we introduced regular dehydration using separators. These modifications led to a significant reduction in contaminant concentration in the lubricant, resulting in a more than 30% decrease in bearing wear during the first six months after implementation.
Staff Training and Long-Term Maintenance
Technical solutions alone are not sufficient if the staff is not adequately trained in their proper application. Therefore, we organized training for maintenance technicians and machine operators focused on correct lubrication procedures, identification of wear signs, and basic bearing condition diagnostics. The training included practical demonstrations of proper lubricant dosing, seal inspections, and interpretation of lubricant analysis results. Emphasis was placed on prevention—such as early detection of leaks or excessive bearing heating.
To maintain the achieved results in the long term, we introduced a system of regular inspections and maintenance, which includes monthly bearing condition reviews, quarterly lubricant analyses, and annual comprehensive machine inspections. This system enables early detection of potential issues and their resolution before serious damage occurs. Thanks to the combination of technical measures and systematic maintenance, unplanned machine downtime was reduced by 50%, and the intervals between major overhauls were extended by 25%.
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