According to NSK, this capability will reduce the need for grease inspection and replenishment costs and help companies implement condition-based maintenance strategies.
A range of machinery and equipment, from machine tools to railcars, utilise grease-lubricated products like bearings, ball screws and linear guides. However, grease degrades over time as machinery operates, so on-site lubricant inspection is vital to help maximise uptime and OEE (overall equipment effectiveness). In recent years, more companies are said to be switching their equipment maintenance strategy from time-based maintenance to condition-based maintenance. A need, therefore, exists for a grease degradation diagnosis method capable of accurate deployment on site. Such an app would also help combat labour shortages and support carbon neutrality efforts.
Existing diagnosis methods rely on laboratory analysis, but this comes with high cost, a lack of suitability for on-site use, and a long wait for results. Visual observation or densitometer methods are thus more common but suffer from low accuracy. As a consequence, many companies replenish lubricant unnecessarily early to ensure stable operation, resulting in wasteful grease usage.
With this in mind, NSK set out to develop a more accurate method of grease degradation diagnosis. Importantly, the new NSK app can analyse the level of lubricant degradation using just a small sample of grease. Chemical changes to the base oil and additives of the grease occur due to heat from operation and oxidation with the passage of time. These chemical changes are claimed to cause the molecular structure of the lubricant to change and absorb more short-wavelength light, affecting its colour. Grease itself starts off white when new, turning yellow or orange with use and eventually becoming black, which indicates zero remaining life. The NSK app quantifies grease by its colour to calculate its remaining life.