• How is a hydrodynamic bearing from Miba constructed?

Miba is flexible in the production of bearings. In principle, half shells and bushings as well as assembled bearings can be developed and produced. Half shells and bushings can be made of several layers of different materials. This multi-layer design enables higher loads to be accommodated. We can flexibly adjust the properties of the materials to maximise the performance and life of the bearings. The design of the assembled bearings can be flexible and ideal for high speed and dynamic applications.

• What is required to install a hydrodynamic bearing?

Installation is straightforward and requires some experience with mechanical components. Careful preparation of the bearing points is required to install a hydrodynamic plain bearing. Correct installation ensures that the bearing performs to its full potential and achieves a long service life. If required, Miba can assist with instructions and technical recommendations to make the installation as smooth as possible.

• What is the service life of a bearing?

The service life of a hydrodynamic bearing is generally long and can be several years under optimum conditions. Factors such as load, speed and lubrication play an important role. Miba provides support with the design and calculation in order to achieve a long service life.

• In what speed range can the bearings be used?

Hydrodynamic bearings can be used in a wide speed range from very low to high speeds (120m/s). The application range depends on the design of the bearing. Miba offers customised solutions for different speed requirements.

• What is a hydrostatic bearing?

A hydrostatic bearing is a type of hydrodynamic bearing that is supplied with a continuous film of lubricant by an external pump to keep the shaft in suspension, thus avoiding direct contact between the bearing surfaces. In contrast to hydrodynamic bearings, which build up their lubricating film through the movement of the shaft itself, a hydrostatic bearing generates this film independently of the speed through the targeted use of pressurised oil.

• What materials are used for bearings at Miba?

Aluminium, bronze and white metal. Our bearings are also available lead-free on request. Our alloys have been carefully developed to ensure excellent wear resistance, low friction and a long service life. State-of-the-art coating processes such as electroplating, sputtering and Synthec® are available.

• Why is a coating important?

Coating can be critical for certain applications to optimise the performance and service life of slide bearings. It reduces friction and wear, increases load capacity and protects against corrosion.

• Can layers flake off?

Miba produces multilayer bearings using several processes.These include processes that have been established for decades, such as casting, cladding and laser cladding.The quality of the bond is ensured in the course of quality control.

• What is the hardness of the bearing materials?

The materials for plain bearings are carefully selected to offer a perfect balance between hardness and wear resistance. This ensures a long service life and high load capacity, even in extreme operating environments. Depending on the base material and multi-layer structure, the hardness is between 20HV and 170HV.

• What is the temperature limit of the bearings? 

Slide bearings can be used in high-temperature environments without any problems. Depending on the materials and lubricants used, they are able to withstand temperatures of up to 250 °C without losing their performance.

• What must the mating surface for the slide bearing look like?

The mating surface of a slide bearing should be smooth to ensure optimum operation (roughness of approx. Ra <1µm). A well-machined and hardened surface contributes to the longevity of the bearing.

• In which applications are hydrodynamic bearings used?

Hydrodynamic bearings are used in a wide range of applications, including motors, gearboxes, turbines, generators, pumps, combustion engines, compressors and many industrial drives. They are particularly suitable for applications where high dynamic loads, speeds and reliability are required, as well as a long service life and low maintenance costs. Find out more in our blog article.

• What are the advantages and disadvantages of hydrodynamic bearings compared to rolling bearings?

Advantages: Smaller installation space, theoretically infinite service life in hydrodynamic operation, low component weight, noise-reducing, fewer components

Disadvantages: Oil supply necessary

Read more about rolling bearings vs. hydrodynamic bearings in our blog article.

• How does Miba ensure that the bearings work for the application?

Miba provides support with extensive tests and simulations to ensure that the bearings meet the requirements of the respective application. The operating conditions are analysed in detail and the bearings are designed accordingly.

• Does Miba offer self-lubricating bearings?

No, Miba does not currently offer self-lubricating bearings. Instead, we focus on our core competences in the field of hydrodynamic and hydrostatic bearings, where we ensure maximum reliability and efficiency through decades of experience and innovative technologies.

Read more about the lubrication of slide bearings in this blog article.

• Do I need an additional pump?

A hydrodynamic bearing requires an active oil supply. If active lubrication is available for a system, it is usually possible to lubricate the slide bearing using the existing pump system. If there is no active lubrication, a pump that can supply at least 1 bar overpressure at the bearing points must be selected.

• Which lubricant can be used?

Hydrodynamic bearings are versatile in terms of the lubricants that can be used. Oil is usually used as standard, but other fluids such as water glycol or special high-temperature media can also be used, depending on the requirements of the specific application.

• Does Miba have experience with water glycol lubrication?

Although Miba has not yet realised a series application with water glycol lubrication, we are continuously working on new solutions. Our expertise in the development and customisation of plain bearings enables us to respond flexibly to the specific requirements of our customers. We are always open to testing new lubrication media in order to offer customised solutions that meet the individual needs of our customers.

• What is oil sump lubrication?

With oil sump lubrication, the housing of the bearing serves as a lubricant reservoir - the so-called oil sump. The shaft is immersed in this oil sump with every revolution and thus lubricates itself.

• Which oils can be used?

The choice of oil depends on the operating conditions and requirements. Depending on the application, Miba recommends oils that are matched to the specific loads and temperatures of the area of application.

• How much oil/lubricant does the hydrodynamic bearing need?

We cannot give a generalised answer here. This is because the quantity of lubricant required depends on the type of bearing and the respective application. A sufficiently large supply is crucial to ensure continuous lubrication and prevent overheating. At Miba, the exact quantity is calculated as part of the detailed design of the bearing. This is how we ensure that bearings are optimally lubricated and work reliably.

• How do you deal with the issue of oil compatibility?

Miba attaches great importance to ensuring that the oils used are compatible with the materials of the bearing and the operating conditions. This is ensured through careful selection of the lubricants and comprehensive tests.

• Is oil cooling necessary?

In high-performance applications or at high speeds, additional lubricant cooling may be necessary to keep the operating temperature of the lubricant within the ideal range. Excessively high temperatures can impair the performance of the lubrication and shorten the service life of the slide bearing. Targeted cooling ensures that the lubricant retains its optimum viscosity and works efficiently.

• How high must the oil pressure be?

A minimum supply pressure is usually sufficient to ensure a supply of lubricant.

• What are the oil change intervals?

How often the lubricant should be changed depends on the operating conditions and the type of lubricant. As a rule, the oil should be checked regularly for contamination and wear products. If necessary, it should then be replaced to ensure the optimum performance and service life of your hydrodynamic bearing.

• Does Miba offer maintenance-free bearings?

No, Miba does not offer completely maintenance-free bearings. Instead, we place great emphasis on developing durable and reliable bearing solutions that are low-maintenance and retain their optimum performance over long periods of time with minimal maintenance. With our precisely designed bearings, you can be sure that they offer high operational reliability even under the most demanding conditions.

Learn more about the maintenance of hydrodynamic bearings in this blog article.

• How does maintenance work for hydrodynamic bearings?

The maintenance of hydrodynamic bearings is generally straightforward. It involves regular inspections, checking the oil condition and, if necessary, replacing the lubricant. Thanks to their robust design, these bearings usually require little maintenance.

• Does a hydrodynamic bearing need to be relubricated?

A hydrodynamic bearing generally does not need to be relubricated, as the hydrodynamic principle means that it continuously builds up a stable lubricating film that separates and lubricates the bearing surfaces. As long as the lubricant is present in the system in sufficient quantity and quality and the operating conditions are maintained, the bearing remains reliably and efficiently lubricated over long periods of time.

• What does it take to replace a hydrodynamic bearing?

The oil change intervals depend on the type of lubricant, the operating conditions and the application.Miba recommends regular checks of the oil condition to ensure optimum performance and longevity of the bearing. If a hydrodynamic bearing needs to be replaced, this is done by loosening the screw connection or the mechanical interference fit.

• How often does the bearing need to be replaced?

The replacement intervals for hydrodynamic hydrodynamic bearings depend on the application and the operating conditions.With proper maintenance and the use of a suitable lubricant, these bearings can achieve a very long service life, often several years without replacement.

• How can the bearing service life be checked? Are there sensors?

Yes, there are sensors that can be integrated into hydrodynamic bearings to monitor parameters such as temperature. This data helps to monitor the condition of the bearing in real time and to take early action to increase the service life.

Learn more about methods to prevent bearing damage in this blog article.

• How many start/stop cycles can a bearing withstand?

There are several options for slide bearings to fulfil start/stop requirements. On the one hand, materials have a natural resistance that allows long-term, virtually wear-free start/stop operation. If this resistance is exceeded, operation with controlled wear is possible. A hydrostatic lift can be realised in the design, which ensures start/stop operations under permanent hydrodynamics and thus freedom from wear. Another option for enabling a high number of start/stop operations is to design slide bearings with special coatings that have been specially developed for start/stop conditions.

• What happens in the low speed range/ when starting up?

At low speeds below the load and lubricant-dependent limit speed, mixed friction occurs. There are several remedies to prevent this and reduce possible wear. Coatings can be applied directly to the bearing. These coatings are specially designed for the start-up of plain bearings. In some cases, a hydrostatic starting aid can also be useful.

• What happens with heavy loads at bearing standstill?

There are several remedies for heavy loads at standstill. It is possible to apply coatings directly to the bearing. These coatings are specially designed for the start-up of plain bearings. In some cases, a hydrostatic starting aid can also be useful.

• What happens with an Uneven Load?

Slide bearings are excellent at compensating for uneven loads. Thanks to their design, they can distribute the load evenly and thus prevent excessive wear and undesirable operating faults. This can be achieved by a segmented bearing that adapts to the load. The slide bearing materials used offer the possibility of running-in. As a result, the surfaces fit together perfectly.

• What happens in the event of an emergency run?

For hydrodynamic bearings, emergency running means the failure of the active oil supply.In such a condition, the remaining oil in contact and in the immediate vicinity has a lubricating effect. If this reservoir is exhausted, hydrodynamic bearing materials offer emergency running properties due to their heterogeneous structure. Low-melting alloy elements usually melt and act as a lubricating medium.This double bottom allows operation beyond the set application limits in order to delay immediate failure.

• What happens to the mating material during emergency operation?

In emergency operation, the mating material is protected by the special design of the hydrodynamic bearings.The bearing materials are selected so that they wear rather than damage the mating material in the event of lubrication failure.

• What tolerances are possible?

Hydrodynamic bearings offer a high degree of flexibility in terms of manufacturing tolerances. This tolerance makes it possible to ensure a reliable and stable bearing even with slight deviations in the fit.

• What inclined positions and deflections are permissible?

Hydrodynamic bearings are tolerant of skewing and deflection. Their design and choice of material allows them to adapt to slight deformations without impairing their function or service life. Under certain circumstances, it may also be possible to provide for specific geometric misalignments and deflections.

• What misalignment is permissible?

Hydrodynamic bearings can easily compensate for moderate misalignments. Their adaptability and the large-area contact ensure that an even load distribution is guaranteed even with slight misalignment.

• What happens to the bearing when it is tilted?

Hydrodynamic bearings are tolerant of misalignment. Due to their design and the large-area contact point, they can compensate for misalignments well, which makes them an excellent choice for applications with complex load profiles.

• What loads can the bearing support?

Due to the flexible multi-layer design of the bearings, they can support loads of up to 160 MPa.

• Can the bearing rotate in both directions?

The ability to allow the formation of a hydrodynamic lubricating film in both directions of rotation can be taken into account in the bearing design.

• What about power loss in hydrodynamic bearings?

Hydrodynamic bearings are characterised by their robust design, which ensures efficient power transmission. Modern lubricants and optimised designs have minimised the power loss so that plain bearings work reliably and economically.

• What are the frictional losses of hydrodynamic bearings compared to rolling bearings?

Thanks to the continuous development of bearing materials and design, friction losses in hydrodynamic bearings are minimised. Particularly with the right lubrication, hydrodynamic bearings run with low losses and thus contribute to efficient operation. At low speeds in the mixed friction range, hydrodynamic bearings usually exhibit higher friction losses. At higher speeds, however, the friction losses of hydrodynamic bearings are lower than those of rolling bearings. In this comparison, the design of the rolling bearing and the operating conditions must be taken into account.

• How does the efficiency of hydrodynamic bearings compare to rolling bearings?

Hydrodynamic bearings are efficient, especially under heavy loads and in demanding environments. Their ability to adapt to different operating conditions ensures consistently high efficiency over long operating periods. Read more in this blog article.

• How does a hydrodynamic bearing handle shocks and vibrations?

Hydrodynamic bearings are very robust against shocks and vibrations. The lubricant film acts as a damper, absorbing unwanted movements, which results in smooth and stable bearing operation. This makes these bearings especially suitable for applications with high dynamic loads.

• Can a hydrodynamic bearing be used in dirty or dusty environments?

Yes, hydrodynamic bearings can also be used in dirty or dusty environments. By carefully selecting bearing materials, the bearing can be tailored to withstand challenging environmental conditions. Additional seals and protective measures can be implemented to further extend the bearing’s service life in such conditions. Hydrodynamic bearing materials have the ability to embed foreign particles, rendering them harmless to the bearing. Moreover, with smart design, the oil supply can be arranged to flush out potential particles from the lubricant gap before they enter the pressure buildup area.

• How is the bearing sealed?

Hydrodynamic bearings can be effectively sealed. Depending on requirements, various types of seals, such as labyrinth seals, can be used to keep dirt out and ensure the lubricant stays securely within the bearing.

• How does a hydrodynamic bearing handle constant changes in rotational speed?

Hydrodynamic bearings are highly adaptable and respond flexibly to changes in rotational speed. They form a stable lubricant film that provides optimal protection even under varying operating conditions.

• Is prior knowledge required for the design of hydrodynamic bearings?

No, prior knowledge is not required for the design of bearings. Our team of experts provides comprehensive support from the initial consultation to successful implementation and beyond. Additionally, we have extensive in-house simulation and testing capabilities.

• What bearing sizes does Miba offer?

Miba offers a wide range of bearing sizes, from small bearings (approx. 10 mm) for special applications to large bearings (up to approx. 3,500 mm) for turbine applications in hydroelectric power plants. We specialize in developing flexible bearing solutions tailored to the specific requirements of your application, whether standard or custom-sized bearings.

• What types of bearings does Miba generally offer?

Hydrodynamic slide bearings

Hydrostatic slide bearings

Half-shell bearings, bushings, and built bearings

Metallic bearings

• Can Miba provide samples or prototypes for testing?

Yes, Miba can provide samples or prototypes for testing. Contact Miba to discuss requirements and availability.

• What production volumes are of interest to Miba?

Thanks to our flexible production concept, we can accommodate both small and large production volumes. Depending on the application and requirements, we can offer customized solutions tailored to customer needs.

• What are the minimum annual production quantities?

Minimum production quantities depend on the type of bearing and the specific application. Miba strives to offer flexible solutions to customers and can also fulfill small batch sizes, especially for specialized applications.

• Does Miba supply clinched bushings?

No, Miba does not offer clinched bushings but instead uses rolled bushings made from solid material to meet the highest demands for performance and quality.