Causes of Over-Lubrication
Over-lubrication means applying an excess of lubricant. This usually happens due to a lack of knowledge, using the wrong lubricant, or using the wrong equipment.
Lack of knowledge
When there is insufficient knowledge about the functioning of lubricants, people tend to think "too much is better than not enough." Maintenance personnel assume that the excess lubricant will naturally come out and that the optimal amount will remain behind. This is far from true. Excess lubricant can remain in the spaces between moving parts under high pressure. As a result, these parts have more difficulty moving through the lubricating layer, leading to increased stress on these components and ultimately on the entire machine.
Wrong lubricant
A lubricant must be suitable for the application. The composition and viscosity, among other factors, must withstand the prevailing temperatures, pressures, and speeds. When the wrong lubricant is used resulting in insufficient lubrication, people often think the quantity is the issue. Extra lubricant is added as a result. This will not lead to improvement but rather to over-lubrication and its associated disadvantages.
Effects of Over-Lubrication
The effects of over-lubrication are diverse. But they are all negative.
Unnecessary high lubricant consumption
An obvious disadvantage is the wastage of lubricant. Over-lubrication always means an excess of lubricant and thus unnecessary consumption.
Reduced component lifespan
When there is an excess of lubricant, for example, in a bearing, it will have more difficulty moving through the grease. This leads to additional heat generation and increased stress on the machine and drive. These high temperatures and pressures can significantly shorten the lifespan of a bearing, as well as any associated applications. The seals can be damaged and, of course, energy consumption increases.
Reduced lubricant lifespan
Furthermore, a snowball effect occurs. Due to the higher temperatures and pressures, the quality of the lubricant also deteriorates. This will cause the lubricating ability of the grease to decrease much faster than expected, resulting in increased friction in the bearing and further temperature rise. Again, this leads to accelerated degradation of both the machine component and the lubricant itself.
The following rule of thumb shows how quickly the quality of a lubricant decreases with increasing temperatures:
Every 10°C temperature rise above 65°C halves the lifespan of the lubricant.
This means that a lubricant that lasts one month at 65°C will only last two weeks at 75°C, one week at 85°C, and just a few days at 95°C.
The reason for this dramatic reduction in lifespan is due to the lubricant’s composition. In essence, a lubricant consists of a base oil, additives, and in case of a grease, a thickener. When temperatures rise, the oil can evaporate and carbonize, resulting in a stiff residue. The first indication temperature has risen beyond a grease's maximum temperature limit, will be bleeding of the base oil, resulting in the same carbonized residue.
Carbonized particles and a dried thickener in a grease will no longer provide adequate lubrication, which in turn leads to excessive heat and noise generation, and ultimately, the seizing of components.
Measures
Lubrication should be considered a precise, proactive task that is essential for the proper functioning of production equipment in any facility. In addition to using the correct amount of lubricant, selecting the right lubricant is crucial. It requires training and experience to make the correct recommendation.
To prevent over-lubrication, various measures can be taken:
Determine the required amount of grease
Over-lubrication can be avoided by accurately knowing how much grease an application requires. Often, this information can be found in the machine builder's manual, but it can also be determined empirically by collecting, storing, and analyzing relevant data over an extended period.
Implement automatic lubrication
When maintenance personnel are aware of the need for sufficient, but not excessive, lubricant, one of the solutions is to apply the right amount of grease using an automatic lubrication unit. For example, the Interflon Single Point Lubricator or the Interflon Oil Dispenser, which automatically applies the pre-set amount of grease to the correct location.
Calibrate the grease gun
Administering the correct amount of grease is only possible when you know how much grease each grease gun delivers per stroke. This can be determined by measuring the amount of grease dispensed, either by mass or volume. Only with this information can the desired amount of lubricant be accurately applied.
Record lubrication activities
When starting to establish lubrication maintenance, it is wise to build a database that includes all important information about lubrication tasks. Start with the most critical or frequently malfunctioning machine. Which lubricant is applied, how frequently, and at which specific lubrication points? What are the findings? By building a history, trends over time can be determined to assess whether the lubricant and lubrication frequency have been appropriate. Trend analysis can also determine the effectiveness of certain changes. This can be done using maintenance software such as ILAC Pro.
Measure sound and vibrations
Analysis equipment that measures both heat and vibrations is ideal for detecting whether an application is adequately lubricated on-site. These precision instruments indicate when lubrication has reached the optimal level and when it is time to stop applying lubricant. The tools can also be used to measure and monitor the current lubrication levels.
Appoint a responsible person
Assign a suitable employee as the "owner" of lubrication maintenance. This person is then responsible for proper planning, making the right choices, and ensuring proper follow-up by colleagues.
