Durolub DL general information

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About Durolub DL

Durolub is a mix of ultra high molecular polymers and synthetic, temperature stable base oils. Durolub is filled into the free space inside the bearing and then specially heat-treated. Because of the temperature Durolub is hardening to a solid, porouse matrix compound. There are very narrow gaps around the rolling elements and to the raceways. The oil is kept in the polymer – matrix because of its surface tension.

Function of grease lubrication

In order to explain the advantage of the Durolub DL systems we first need to explain the function of grease lubrication.

For grease lubrication usually 25-30% of the free space is filled with lubricant. Typical grease contains around 80% oil and thickeners (soaps). The most common bearing grease are based on mineral oil + lithium(complex) soap, which is a proven and cheap solution for many bearing applications.

During operation the grease is overrolled, excess grease is pushed out of the raceways and out of the bearing. Most of the excessive grease is not flowing back to the raceways and therefore not available for lubricating the contact zone.

Furthermore, too high grease filling amounts cause a high bearing friction torque, this without increasing the operating time of the lubricant noteworthy. Higher grease amounts will be pushed out of the bearing and contaminate the surrounding environment.

A change of the environmental temperature will cause condensed water in the free space of the bearing. The water in the bearing will emulsify with the oil in the grease and the efficiency of the lubricant will drop drastically.

Function of Durolub DL lubrication

For Durolub DL lubrication the free space of the bearing is completely filled with the Durolub DL compound. Compared to standard grease filling of 25-30% about 90-100% of the free space is used for the oil storage. And most important, the oil is used effectively at the contact zone, there´s no pushing out of oil as you find it with greased bearings.

During operation the Durolub DL rotates together with the cage and the rolling elements. Because of the movement along the the rolling elements and the raceways there is a constant supply of oil, just exactly at the point of need.

With increasing operating temperatures the oil supply increases. The thermal expansion of the polymer – matrix is smaller than the base-oil and the base oil reduces its viscosity with increasing temperatures.

If operation stops the effect is reverse, the Durolub DL soaks  back the excess oil into the polymer – matrix, it will be used again for the next operating cycle.

The bearing is perfectly lubricated during all operating conditions.

Bearing lubricated with Durolub DL

The main advantages of Durolub DL

Lubricant service life

Durolub DL contains 3-5 times more base-oil than grease lubricated bearings, there´s no pushing out of Durolub DL out of the bearing – Durolub DL remains in place and the oil is available for lubrication during the whole operating life.

The supply of grease is right in acordance with the real demand and directly at the place it´s needed, the  contact zone. Therefore the oil is used extremely effectively.

Durolub cannot be overrolled or churned, what is further extending the lubricant service life.

The high quality synthetic base-oil resists oxidation and resists premature aging. A high viscosity index and the Durolub DL variant base oils offer a wide operating range – from extremely low starting temperatures to 85°C constant (peak 100°C)

As a result, the service life of the lubricant increases significantly.

The bearings are practically lubricated for life – time and don´t need to be relubricated.

Additional sealing effect / support of integrated seals

As the whole free space in the bearing is filled, there a just very little gaps to the bearing rings. Only very little dust or water can enter into the bearing. Durolub DL is very resistant against water and resistant against most acids, leaches and solvents.

At the contact zone there is only a small quantity of oil which cannot emulsify with water. Such emulsification at grease lubricated bearings is the main cause for premature bearing failures in wet conditions.

Integrated bearing seals are supported by the solid Durolub DL compound. While cleaning with water or high pressure devices the seals cannot be pressed into the bearings. Therefore the sealing effect is improved considerably.

Durolub cannot be washed out the bearings in any case.

No condensed water in the bearing

When air cools to its dew point through contact with a colder surface, the airborne water vapour will condense to liquid water at the surface. Such effect is typical for outdoor applications as you find them for instance in cable car rollers or maritime applications.

In normally greased bearings the condensed water inside the bearings will emulsify with the grease and reduce the lubricants effectiveness. Often recommended high grease filling quantities will not avoid the problem, excessive grease will be pushed out of the bearing and in operation the remaining free space will be larger than planned.

As the Durolub DL filled bearing is completely and durably filled, even with very high temperature difference, there will no condensed water in the bearings.

No dripping down / extremely reduced dripping down at vertical installations

With greased bearings excessive grease is pushed out of the bearings, especially higher filling quantities increase the trouble. An effective grease must have the ability to flow back into the raceway, sticky greases reduce the dripping down problem but have the reverse effect of a reduced lubrication effectiveness.

Vertically arranged radial bearings suffer from this effect, typically the relubrication cycle is 50% shorter than for a radial arrangement.

For horizontally arranged Durolub DL lubricated bearings there will be no noteworthy dripping down.

At vertical installations of bearings the dripping down is reduced considerably. With additional bearing seals it can be avoided almost completely.

Food and Drug approval / Antimicrobial option

All Durolub DL are certified H1 for incidental contact with food. Furthermore they are Halal and Kosher certified.

Durolub DL series is optionally available with antimicrobial additives to prevent microbial growth. There will be no microbial contamination of the end-product just in case of incidental contact.

Maintenance cost / Environmental impact

Bearings lubricated with Durolub© contain up to 5 times more oil than greased bearings. Highest quality synthetic oils, which cannot be washed and the support of integrated seals offer the maximum grease life time.

The bearings are practically maintenance free. There is no regular regreasing necessary, no excessive grease is around your applications.

This all saves lots of time, money and is the best solution for the environment

Further technical details

Frequently asked questions (FAQ)

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