Machines in harsh working environments always have a shorter life cycle and have higher chances of failure. Even with a manufacturer’s warranty, the indirect downtime cost will still be significant.
The many fluid and particle condition monitoring tests that provide information about the current mechanical state of a system are a solution to this challenge but may not be able to answer all your questions. When you need to know the failure modes, wear debris analysis can give you a definitive answer. This test is non-destructive which means you do not need to open your machine to conduct this machine check.
Wear Debris Analysis
Separation and analysis of particles produced by wear processes can offer a solid foundation for machine condition monitoring. You can collect particles from oil samples, oil filters, and magnetic plugs and analyze them using a microscope, a scanning electron microscope, or energy-dispersive X-ray spectroscopy.
When it comes to wear debris analysis, the aim is to obtain maximum machine dependability at the lowest feasible cost. Several objectives must be set and met to achieve this goal. These goals provide the blueprint for using wear debris analysis to improve machine dependability.
Defining Wear Modes
After determining the composition, you can use wear debris to reveal the machine’s status. The mechanism of wear and the forcing function, on the other hand, may remain unknown. Attempts to mend or solve issues without addressing the root cause of failure will eventually lead to history repeating itself. This often happens when maintenance teams change the oil or bearing prematurely due to non-complying conditions.
Defining the Operating Life
It’s difficult to get accurate estimations of working machinery’s remaining life. This information helps determine which preventive actions to take and how urgently to carry them out. Wear debris analysis, when paired with all available condition data, may help determine how far wear has advanced and the minimum response time required.
Assessing Severity and Residual Life
The use of wear debris analysis to determine remaining usable life is continuously evolving, and there is still much to learn. Either the severity of the forcing function or the overall progression of the condition appears to influence the rate of change in wear metal production. Experience with previous difficulties can be beneficial in detecting current abnormal wear conditions and their severity levels, especially in analytical ferrography.
Visual Inspection of Particles
The importance of visually inspecting particles in increasing the universe of information cannot be overstated. There are several methods for performing this, but the most prominent are glass slides and patch ferrography.
Finding the proper particles to study is often more important than interpreting the meaning and identity of particles discovered in a routine sample taken from a primary sampling port. Older particles may be crushed, laminated, or corroded, making them difficult to distinguish and complicating the determination of wear mode and location.
Identifying Virgin Particles
Used filters, sump sediment, magnetic plugs, chip collectors, and similar sources are the ideal places to look for virgin particles. Any particle larger than the filter’s mean pore size could be considered a virgin particle in circulating systems with high-capture filters. While such particles may be rare, their appearance and composition can provide critical insights.
Case Study: Application of Wear Debris Analysis
A hammer crusher is one of the key pieces of equipment in cement manufacturing. It breaks down clinker, the primary output of cement kilns, into smaller pieces to prepare it for grinding.” The bearings used in the clinker crusher at a cement plant in Egypt are spherical roller bearings. A lithium complex grease with a synthetic base oil intended for high-temperature applications lubricates these bearings. Bearing defects and issues can interfere with the operations and overall productivity of the plant.
The plant used vibration analysis to monitor the crusher’s condition as part of its predictive maintenance program. They also incorporated wear debris analysis into the program. During one scheduled inspection at 360 RPM, vibration monitoring of the outboard bearing in the third clinker crusher line showed no alarm indications. The maintenance team collected grease samples and analyzed the wear debris. They observed spherical particles of varying sizes, which indicated the severity of rolling-contact fatigue. After visually confirming the bearing’s condition, they replaced the outboard bearing. This case study demonstrates how condition monitoring based on grease debris detection can effectively track machine health and should complement other diagnostic tools.