In maintenance, the question regularly arises as to when a lubricating grease has physically reached the end of its service life. A lubricating grease is considered exhausted when, for example, the oil bound within the thickener has largely separated and bled out, causing the remaining grease to harden significantly. In this condition, a reliable lubricating film can no longer be maintained and the lubricating properties are substantially reduced.

The causes of such failure are varied but can usually be traced back to three main factors:

• Thermal overload accelerates the oxidation of base oils and additives and can destroy the structure of the thickener.
• Excessive pressure forces the base oil out of the soap structure prematurely.

At this critical point, it must be determined whether optimizing the grease quality is sufficient or whether an oil circulation system is the technically superior choice. While greases provide excellent sealing, an oil circulation system is superior wherever process heat must be actively removed from the friction point or where the continuous removal of wear particles is critical for equipment safety. Zeller+Gmelin supports you in this analysis to find the most economical and technically safe solution for your application.

A critical moment in maintenance is the relubrication process or the changeover to a new grease. When two chemically incompatible types of grease are mixed inside a rolling bearing, this can lead to unforeseen complications. Such a mixture inevitably results in a condition that can no longer be technically controlled.

The consequences of incompatibility usually become apparent quickly. The grease can soften drastically and leak out of the bearing, or it can harden so much that the lubrication supply is cut off. In both cases, the result is a defective lubricating film, which leads to increased friction, severe overheating, and ultimately total bearing failure. To prevent this complete destruction of the lubrication point, testing for miscibility is essential before any product changeover. Zeller+Gmelin offers specialized laboratory tests for this purpose to ensure that chemical stability in your bearings is maintained at all times.

A frequently underestimated risk in maintenance is over-lubrication. Contrary to the assumption that more material means better protection, an excessive amount of lubricating grease in the bearing housing can often lead to dangerous overheating of the entire component (hot running). If there is insufficient space for the grease to move and work, internal resistance increases significantly, causing temperatures to rise and prematurely damaging the structure of the lubricant.

To prevent this, the design of the bearing point must be assessed to ensure that excess grease can be discharged in a controlled manner via relief holes. Precise dosing is the key to maintaining a stable thermal balance and preventing unplanned downtime.

Choosing the right grease is a direct investment in the availability of your equipment. As has been shown, it is the precise interplay of chemistry and mechanics that determines whether your bearings will operate reliably over the long term or fail prematurely due to thermal loads and incompatibility. High-performance greases from Zeller+Gmelin provide you with the necessary safety margins for every application.

By combining technologically leading products with our in-depth laboratory analysis, you minimize the risk of unplanned downtime. A strategically selected lubrication concept thus protects far more than just individual components—it sustainably ensures the profitability of your entire production process.

Would you like to assess your lubrication situation or optimize maintenance intervals? Our experts will provide you with non-binding advice to help you achieve more efficient and safer manufacturing.