Lubrication Using Ultrasound Technology

Determining both the frequency and quantity of lubrication are two perplexing issues facing technicians responsible for maintaining bearings. Improper bearing lubrication is responsible for several issues, such as increased lubricant usage, increased bearing purchases (due to failures), increased equipment failures, increased operating temperatures, and motors that run inefficiently. What happens if you use too much (or too little) grease on bearings? asks machinerylubrication.com.

Underlubrication can cause a bearing to wear out before its time, while applying too much lubrication often leads to catastrophic results for the bearing. It can even cause long-term damage to motor coils and windings. Developing a consistent and systematic replenishment approach can go a long way toward ensuring the quality of your relubrication practices.

With the help of ultrasonic tools and a little lubrication knowledge, technicians can make better greasing decisions or even automate the monitoring and greasing process. Although many are utilizing ultrasound in their condition-based monitoring (CBM) program, many are still lukewarm about implementing the acoustic lubrication application as part of a CBM program, writes reliabilityweb.com.

Ultrasounds reveals mistakes

Traditionally, lubrication scheduling has been time-based with equipment suppliers often recommending lubrication schedules set on criteria such as hours of operation. Suppliers frequently also provide instructions on the amount of lubricant to be applied during these scheduled maintenance procedures. It is not uncommon for clients to be told to lubricate at short-term intervals and to add what appears to be excessive amounts of grease. In one instance, a client was advised to lubricate motor bearings every two to three weeks and to add one ounce of grease. The origin of these suggestions leads one to speculate that they are often based on some unknown factors that have no real-world application. Ultrasound usually reveals that people have been applying too much grease.

Ultrasound technology is based on the sensing of high-frequency sounds. Ultrasound starts at 20,000 cycles per second, or 20 kilohertz (kHz). This is considered the high-frequency threshold at which human hearing stops. Most ultrasonic instruments will sense from 20 kHz up to 100 kHz. The range of human hearing covers frequencies from 20 cycles per second (20 Hz) up to 20 kHz. The average human will often hear up to 16.5 kHz and no more.

Failure prevention results in huge savings

Although Ultrasound has many uses and applications, one of the most important is assisted lubrication. Using ultrasound as a tool to assess lubrication levels allows us to know when we need to apply grease and when we have applied enough. It also tells us if there are other problems with the bearing. We can track and trend how much grease we are using on machines (a calibrated grease gun facilitates this) and optimize lubrication PMs (planned maintenance) for both time and frequency, writes Adrian Messer of EU Systems.

When technicians apply acoustic lubrication application, they usually get Asset Condition Management (ACM) domain. Within it, there is an element known as asset condition information (Aci). It comprises all the data, observations and conditions of an asset. This information is more than just current state; it is the cumulative condition of an asset over its lifecycle.

Utilizing a condition-based lubrication strategy means letting the condition of the bearing determine when to lubricate. If a bearing is working properly and does not demonstrate any changes that warrant adding lubrication, the bearing should be left alone. Data collected through CBM is a key component in Aci. This allows to detect early onset failure and is normally aligned to known failure modes. These include vibration analysis, oil analysis, ultrasonic testing, nondestructive testing and any other methodology of analyzing the condition of an asset with regards to its deviation from its normal operating condition.

The identification of early signs of failures benefits in huge savings by reducing loss of production, loss of equipment (asset) and loss of man-hours from unscheduled maintenance.