Reducing maintenance and operating costs

Phil Burge of SKF looks at how developments in lubrication systems, particularly centralised lubrication systems, can reduce maintenance and operating costs of production lines and factory equipment.

Phil Burge, Marketing Manager at SKF, looks at how the latest developments in lubrication systems, particularly centralized lubrication systems, can reduce the maintenance and operating costs of production lines and factory equipment.

Effective lubrication of moving surfaces is essential in almost all industrial applications, ranging from conveyors, chains, shafts and cables to steering axles, pivot arms and lift points.

Although a large number of systems and component sets are supplied as 'maintenance-free' or 'sealed for life', there are many more devices that need regular lubrication to ensure that they operate effectively over the long term.

Unfortunately, lubrication is often carried out inefficiently by plant operators, who at best over-lubricate equipment, wasting materials and polluting the surrounding area, or at worst lubricate moving parts at irregular intervals or, if they are particularly inaccessible, do not add lubrication at all.

Indeed, it is worth noting that, for example, over 36% of all bearing failures result from the incorrect specification and inadequate application of the lubricant.

To overcome these problems, a new generation of automated lubrication systems is now available.

These include centralised systems for use on production lines, printing presses, machine tools and mobile plant and equipment; combined oil and grease units for materials handling robots and automation systems, and dry lubricant sprays for the surface of conveyors and guide rails.

A centralised lubrication system is designed to enable multiple lubrication points or groups of points to be supplied with varying amounts of precisely metered lubricant from one central reservoir.

This type of system ensures that every lubrication point, especially those that are difficult to access, receives an exact and carefully programmed level of oil or grease at the appropriate intervals and, if necessary, in the appropriate sequence, while eliminating the risk of contamination due to over-lubrication.

Perhaps as importantly, as a centralised lubrication system functions automatically while machinery is still running and bearings, shafts or conveyors are moving it is possible to ensure that oil and grease are distributed consistently across all moving surfaces, so that wear and tear, and associated downtime, repair and maintenance costs can be significantly reduced; indeed, the service life of bearings can be increased by a factor of at least four in most applications.

In addition, routine maintenance of a centralised lubrication system is generally minimal, being limited to topping up the lubricant reservoir and an occasional inspection of the lubrication points.

Moreover, by comparison with manual lubrication procedures, a centralised lubrication system can reduce the use of oils and greases by as much as 90% due to the precise, demand-orientated metering rates.

There are various types of centralised lubrication systems for use in a wide range of applications.

For example, single-line systems, such as might be used on printing machines typically feature piston distributors to feed metered quantities of lubricant to bearings, cams, gears and power trains.

Generally based on a modular construction, single-line systems can easily be extended by adding additional lubrication points as the needs of the application change, and can serve up to several hundred lube points from a single supply unit and dedicated control mechanism.

Other types of centralised lubrication include circulating-oil systems that are used both to provide a constant supply of oil and for cooling purposes, with the oil or grease being collected after it leaves each lubrication point and is then filtered and re-circulated; this type of system is ideal for lubricating standard bearings and can be particularly cost effective in large power plants, sawmills or cement factories.

By comparison, progressive and zoned lubrication systems are designed to provide a sequential and metered supply of lubricant to individual components or parts of a production line, such as might be found in food and beverage filling plants, where there is typically an extensive network of sterilising, filing and capping machines situated along lengthy conveyor belts.

Finally, travelling lubricators are ideal for use with moving conveyor chains on assembly lines, or painting and coating lines to ensure that every chain link is effectively lubricated as it moves; indeed, the latest travelling lubricators can work with chain conveyors moving at speeds of up to 2m/s.

It is also important to select the correct type of lubricant for each application, taking into account factors that may affect the long term chemical and physical characteristics of the oil or grease and thus its ability to protect moving parts.

Typically, these factors include high operating temperatures, fast line speeds, heavy bearing loads or the use of steam cleaning systems, each of which can degrade the performance of lubricants.

The value and importance of correct lubrication should never be underestimated.

By selecting both the correct method of lubrication and type of grease or oil for each specific application plant and production engineers can achieve long term, trouble free operation, with the minimum of maintenance and downtime, as well as increased line or machine performance.

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