Bearing Damage & Failure Analysis
In most applications, bearings outlive the equipment in which they’re installed. Only some fail, so the question is: why? While this is a common question, it is not always easy to answer. There are many factors that contribute to bearing damage and, ultimately, failure. When a problem within the machinery occurs, inspection and troubleshooting help you understand what is happening and the severity of the bearing damage. The most important part of bearing repair is to properly diagnose the root of the problem.
Early indications of bearing damage range from machinery that is running unevenly, machinery that is running at an extremely loud volume or reduced accuracy. The next installation of our blog explores the most commonly identified causes of damage for several types of bearings including cylindrical, spherical, tapered and ball bearings. During your inspection, look for these signs of damage to the machinery bearings.
Determining Common Types of Bearing Damage
Foreign materials like sand and fine metal in the bearing will cause excessive abrasive wear. After prolonged exposure, this can create reduced fatigue life and misalignment in the bearing.
Pitting & Bruising
Harder particles (metal chips, dirt) that roll through the bearing can cause pitting and bruising of the rolling elements and races. When these particles travel through the lubricant and bearing, eventually they bruise or dent the surfaces.
Etching, commonly known as corrosion, is one of the most serious problems bearings encounter. Etching is often the result of condensation collecting in the bearing houses from changes in temperature. Moisture seeps in through damaged, worn or inadequate seals.
We have discussed in length about the importance of grease & lubrication for bearing maintenance. There are many factors to consider when it comes to lubrication including the amount, type, grade, supply system, viscosity and additives. Selection of lubricants should be based on history, loading, speeds, sealing systems, service conditions and expected life.
Excessive Preload or Overload
This type of damage can generate a lot of heat and cause damage similar to inadequate lubrication. The two are often confused so it is important to check the bearing thoroughly to determine the root issue.
Common causes of misalignment include:
- Inaccurate wear of housing or shafts
- Deflection from high loads
- Out-of-square backing shoulders on shafts or housing
Improper Fit in Housings or Shafts
Always follow the manufacturer’s guide for bearing installation to ensure proper fit and performance. The bearing race (where the rotating load exists) is applied with a press or tight fit. Whereas the races on a stationary axle are applied with a loose fit.
Burns from Electric Current
Arching happens when an electric current that passes through a bearing is broken at the contact surfaces between the races and rolling elements. Each time the current is broken, it produces a pit on both parts and, eventually, fluting develops.
Causes of arching include:
- Static electricity
- Faulty wiring
- Improper grounding
- Inadequate/defective insulation
- Loose rotor windings
Extend the Life of Bearings with Regular Inspections
Many times, we find our clients rush to replace the damaged bearing to quickly move on with production. While it may seem like the better option, taking the time to understand the cause of impairment can extend the life of the bearing and prevent long-term damage to your expensive machinery. Instituting regular maintenance inspections helps to avoid bearing damage before it happens.
Bartlett Bearing Company has a 24/7 technical service department dedicated to helping you solve problems related to bearings used in electric apparatus applications. Since inception in 1951, our promise has always been an unwavering commitment to serving our customers. Call your closest Bartlett location to speak to a member of our technical support team to help solve your bearings issues.