In the food industry, comprehensive cleaning regimes are commonplace, as companies look to meet stringent sector requirements on hygiene. However, such practises can prove detrimental to production line components, not least the bearings that provide motion in critical machinery, equipment and systems.
Spraying with hot steam, high-pressure water jets or very strong cleaning agents can cause two principal problems: foreign objects entering the bearings; and lubricant being washed out of the bearings. For these reasons, NSK offers a range of Moulded-Oil bearings that is purpose designed to deliver extended operating life in harsh food industry environments.
The lubricant within Moulded-Oil bearings is durably incorporated inside a stable carrier medium, an oil-impregnated polyofin resin. This type of lubricant cannot be washed away by steam or liquids, and prevents contamination from entering the bearing. Moreover, as the carrier only releases the lubricant slowly, sufficient lubrication is maintained over a long operating period.
The Moulded-Oil bearings range includes deep groove ball bearings, spherical roller bearings and tapered roller bearings, in several product series and in special forms such as housed bearing units. The range also includes Moulded-Oil bearings made of stainless steel.
These products are suited to a range of food industry applications, where many manufacturers of machines and systems install Moulded-Oil bearings as part of the original equipment. However, they are also ideal for retrofit applications.
A case in point can be seen at a British food manufacturer, where the standard deep groove ball bearings in a seven-track conveyor system were only lasting for a period of four months. The reason was water penetration within the bearings during daily washouts, which resulted in costly maintenance work and damage to the conveyor belts. Each time there was a failure, the company had to endure downtime of 24 hours, creating a considerable dip in productivity.
After inspecting the bearings, NSK recommended using stainless steel bearings with Molded-Oil lubrication and DU seals on both sides. Subsequently, bearing operating life increased three-fold, to 12 months, while bearing-related maintenance costs (including downtime) were reduced by more than €52,000 annually.
This confirms one of NSK’s ‘rules of thumb’, that in applications where the environment is contaminated by moisture and dust, the service life of Molded-Oil bearings in stainless steel is more than twice that of bearings with conventional grease lubrication.