DUROLUB solutions for: high temperature applications up to 350°C

 

The next generation bearing lubrication made available to everyone by THB

High operating temperatures demand special solutions for rolling bearings. With Durolub we offer a full range of solutions, from the G-series lubrication, the special compound Durolub SLC to our ready to use bearings for kiln trucks.

There is no ultimate or unique high temperature solution, in order to obtain maximum operating time and reliability at reasonable cost the application needs to be analyzed in detail. The main parameters to find the optimized solution are operating temperature, speed, load and the environmental condition around the bearing.

thb has a longlasting experience in both – bearings and lubrication. Just contact us for an advanced solution!

Bearing Material

Using rolling bearings above their designated operating temperature (bearing producers thermally stabilize rings and rolling elements between 120 and 200°C, depending on type) will cause a change in the martensitic structure, resulting in a growth of rings.

For low speed applications, as you find them in kiln trucks, such structure change will have no impact on the bearing performance as long as the bearing has enough radial clearance to compensate the growth of rings. For higher speeds the bearings need to thermally stabilized at least at the expected operating temperature. Higher stabilization reduces the hardness and subsequently the bearing life-time.

If the (cost-effective) standard materials are not sufficient then there is no other choice than to utilize special high-temp steel or ceramics or hybride solutions of both.

Such bearings are often difficult to get – thb cooperates with makers of special bearings in Europe and Asia and can offer modified standard bearings as well as tailor made special bearings.

Lubrication

With increasing temperatures the viscosity of oil (oil in the grease) is getting lower, the oil is not anymore capable of separating the rolling elements from the raceway. The metal to metal contact increases wear and causes premature bearing failure.

Grease is ageing quickly at higher temperatures, permanent regreasing is expensive. Excessive grease will be around the bearing (danger of fire!) and old grease in the bearing tends to carbonize.

The todays absolute temperature limit for grease is 260°C, above that level solid lubricants like MoS2, PTFE or graphite Durolub SLC The Durolub SLC is a solid compound consisting of a mix of dry-lubricants with high temperature resistant bonding agents. It is filled into the free space of the bearing and thermally treated. After hardening, the solid compound is moving with the cage and the rolling elements around the bearing. While moving small quantities of the dry lubricant are transferred onto the raceway and rolling elements and build an approx.

1 μm thick layer, which avoids metal to metal contact. The high filling volume of Durolub SLC ensures long lasting operation times at temperatures up to 350°C, even higher peak temperatures do not Baking oven / Food industry are used. Such dry lubricants can be applied dry, as sliding laquer or in combination with a synthetic oil, which evaporates at a defined temperature (e.g. Durolub G400 and Durolub kiln truck bearing suffix S201). The todays high end solution for dry lubricant application is the transfer – lubrication. There are solutions available with cage segments / cages made of graphite and compound solutions filled into bearings (see Durolub F228 and Durolub SLC). As a matter of fact the more lubricant is available in the bearing the longer the operating time will be.

Durolub SLC

The Durolub SLC is a solid compound consisting of a mix of dry-lubricants with high temperature resistant bonding agents. It is filled into the free space of the bearing and thermally treated. After hardening, the solid compound is moving with the cage and the rolling elements around the bearing. While moving small quantities of the dry lubricant are transferred onto the raceway and rolling elements and build an approx. 1 μm thick layer, which avoids metal to metal contact.

The high filling volume of Durolub SLC ensures long lasting operation times at temperatures up to 350°C, even higher peak temperatures do not interrupt the lubrication. Furthermore Durolub SLB is extremely resistant against water, chemicals and most solvents.

Durolub SLC can be filled into many different types of bearings, typical are single row ball bearings and spherical roller bearings.

Durolub Kiln Truck Bearings – A Ready To Use Standardized Product

Kiln truck bearings usually operate at low speeds and high temperatures. The combination of low speed and low viscosity oil at higher temperatures reduces the lubrication performance drastically – very often dry lubricants are the only option. We´d like to shortly introduce 2 Durolub variants for this purpose (others are available – just contact us)

The base ball bearings are made of a forged high performance bearing steel. All surfaces are manganese phosphatized, the internal radial clearance is a multiple of C5 and bearings are available open or with 2 shields (ZZ). The Durolub suffix range from 200 to 240 are reserved for these base bearings and its variants.

S201 – is lubricated with a polyglcol – dry lubricant mixture, the lubricant is suitable for temperatures as high as 450°C – we recommend a max. temperature of 350°C S228 – is lubricated with the Durolub SLC compound suitable for temperatures up to 350°C

For any further details just contact:
Tel. : +43 676 3973077
Mail : office@thb.at
Web : www.thb.at / www.durolub.com
Address: Langwieserstrasse 134 4802 Ebensee / Austria