We are often asked which bearing types we can monitor at HCP Sense. The good news is: Almost all of them!
However, as there are an incredible number of different bearing types and it is easy to lose track of them, this article is intended to provide some clarity. The basic rolling and plain bearings are described below, along with their areas of application, mode of operation, advantages and disadvantages. We will also explain how we can monitor these bearings and what added value they offer you!
Rolling bearings
Rolling bearings can be found in almost all machines and enable low-friction load transmission and rotation of machine elements. The basic design of this type of bearing is mostly similar. They consist of an outer ring, an inner ring and rolling elements in between, which are kept at a distance from each other by means of a retainer.
There are numerous types of rolling bearings, the main difference being the design of the rolling elements, which are either in the form of rollers or balls. These can be further subdivided into various bearing subtypes.
Today, rolling bearings are available in all sizes and a wide variety of materials. As a rule, the dimensions are standardized, but there are also special bearings that are tailored to specific applications.
Lubrication in rolling bearings plays a crucial role in minimizing friction and wear. In general, a distinction is made between three different types of lubrication: oil lubrication, grease lubrication and solid lubrication. The task of the lubricants is to separate the contact partners from each other as effectively as possible. In the case of liquid lubricants, this mainly depends on the viscosity, the relative speed of the contact partners, the surface pressure and the lubricant used. In the case of rolling bearings, these parameters result primarily from the speed, the bearing load, the lubricant used and the temperature.
Depending on the load direction, bearings are divided into radial and axial bearings. The contact angle is used to classify these two bearing types. This angle, which lies between the radial plane and the contact line, serves as a benchmark, whereby the position of the contact line is largely dependent on the rolling elements and raceways used.
Radial bearing: 0° < α < 45°
Axial bearing: 45° < α < 90°
Rolling bearings can be used in all areas in which mechanical components are in rotation. Their range of applications extends from large wind turbines and the mobility sector to small electric toothbrushes. For example, they are used in aircraft engines and in the turbines and rotors of helicopters. Rolling bearings are also installed in turbine pumps and satellites. In both the aviation and automotive industries, they can be found in the chassis as wheel bearings or in gearboxes. Roller bearings are also suitable for use in electric motors or as clutch bearings. Other areas of application include the bicycle industry, railroad technology, robotics, the food industry and agricultural and construction machinery.
It quickly becomes clear that rolling bearings are indispensable in almost every industry!
Functionality and areas of application of the rolling bearings
Roller bearings can take the form of ball bearings or roller bearings. Rolling elements for roller bearings include cylindrical rollers, needles, rollers, tapered rollers and barrel rollers. The main types of roller bearings and their properties are explained below.
Deep groove ball bearing
The deep groove ball bearing is the most common rolling bearing and can be found in numerous applications. It consists of an inner and outer ring, between which balls are located to transfer the rotation from one element to the housing. A rolling bearing retainer holds the balls in position and guides them through grooves in the bearing. There are also double-row deep groove ball bearings, although these are used much less frequently than single-row deep groove ball bearings. Depending on requirements and application, the inner structure of the bearing can be sealed to protect it from dirt, for example.
Deep groove ball bearings are widely used in mechanical engineering and vehicle construction for bearing arrangements that do not have to meet any special requirements.
Angular contact ball bearings
Angular contact ball bearings are also available in single-row and double-row designs. This type of bearing is used when both large radial and large axial forces occur and precise axial guidance is required. The contact points of the rolling elements with the bearing rings determine the contact angle. Since single-row angular contact ball bearings can only support axial loads in one direction and radial loads always cause an exact reaction force, a second bearing is required to provide counter guidance. This type of bearing must therefore always be used in pairs and mounted against each other.
Angular contact ball bearings are suitable for supporting shafts that are as short and rigid as possible under high radial and axial loads. These include, for example, worm shafts or vehicle axles.
Cylindrical roller bearings
In cylindrical roller bearings, the rolling elements are cylindrical. This means that the contact between the rolling element and the bearing ring is a line contact. Cylindrical roller bearings therefore have a greater load carrying capacity than deep groove ball bearings with the same dimensions and are more suitable for impact loads.
Cylindrical roller bearings are not self-retaining and can therefore be easily dismantled. This enables the inner and outer rings to be fitted separately.
This type of bearing is frequently used in electric motors and gearboxes, as well as in axle bearings of rail vehicles and rolling mills.
Barrel bearings
Barrel bearings are equipped with barrel-shaped rollers and the raceways of the outer rings are ground as hollow balls. Such bearings can be pivoted, which improves their use in the event of misalignment. They are used in heavy engineering, rolling mills, paper machines, lifting equipment, axle bushings for heavy rail vehicles and conveyor pulleys.
Spherical roller bearings
Double-row barrel bearings are also known as spherical roller bearings. In addition to radial forces, they are also able to support large axial forces in both directions. Due to their design, misalignments of up to 4° can be compensated. This type of bearing is considered the bearing with the highest load capacity.
Similar to the barrel bearing, the area of application of the spherical plain bearing includes heavy engineering, rolling mills, paper machines, lifting equipment, axle bushings for heavy rail vehicles and conveyor pulleys.
Advantages and disadvantages of rolling bearings
Advantages
- Low wear even at low speeds (from mixed friction)
- High degree of standardization
- High load capacity
- Wide variety
Disadvantages
- Increased noise level
- Sensitive to impact loads
- Sensitivity to contamination
Which bearing types can HCP Sense monitor?
Due to the inherent properties of rolling bearings, we can use our patented technology to easily monitor any type of rolling bearing, provided they are made of metal. Simply put, the raceways of the bearing in combination with the rolling elements and the lubricant represent a capacitor whose electrical resistance changes depending on the operating conditions of the bearing. This electrical alternating current resistance is expressed as impedance, which forms the basis for our evaluation.
You can find more information on how our technology works here:
Plain bearings
Plain bearings are used to guide components moving relative to each other with high precision, minimal friction and minimal wear, while at the same time transmitting forces between the friction partners. Depending on the type and direction of the forces that occur, a distinction is made between statically and dynamically loaded radial and axial plain bearings. Oil, grease or solid lubricants are used to lubricate plain bearings. However, there are also plain bearings that are used without lubrication.
Plain bearings are highly resistant to shocks and vibrations and also have a damping effect on vibrations and noise. They tolerate low levels of contamination and, with the right choice of material and regular maintenance, can achieve a practically unlimited service life. Thanks to their design, plain bearings are suitable for use at very high and low sliding speeds. The design of this type of bearing is comparatively simple and they require little installation space. Plain bearings can be designed as both unsplit and split versions, which simplifies their installation and maintenance.
Functionality and areas of application of the plain bearings
Plain bearings are used in a wide range of machines and devices of all kinds. They are particularly common in applications such as internal combustion engines, where they are used in crankshaft, connecting rod, piston pin and camshaft bearings. They are also found in piston compressors and pumps and play an important role in gearboxes, steam and water turbines and generators. Plain bearings are also used in centrifugal and gear pumps. They are also indispensable in machine tools, ships, rolling mills and presses.
Apart from industrial applications, plain bearings are also used in agricultural and household technology, office technology and consumer electronics. Their diversity and efficiency make them an indispensable component in numerous technical systems.
The various types of plain bearings differ mainly in terms of their materials. These are decisive when it comes to designing a plain bearing for the corresponding area of application. When selecting a suitable plain bearing, it is particularly important to ensure that the
- the material and the lubricant are matched to each other
- the lubricant wets the friction surface well
- the material has good emergency running properties
- the material has high wear resistance
- the material has high thermal conductivity
The common bearing types of plain bearings are presented below.
Hydrodynamic plain bearing
A hydrodynamic plain bearing is a type of bearing in which there is minimal play between the bearing and the shaft. This clearance is filled with lubricant. When at rest, the shaft rests on the plain bearing.
When the shaft begins to rotate, lubricant is drawn into the gap between the bearing and shaft. This forms a lubricating film underneath the shaft, which lifts the shaft. As a result, the plain bearing and shaft no longer touch and are separated from each other by a lubricating film.
This type of bearing is suitable for high bearing forces and high speeds, whereby the lubricating film has a damping effect.
Hydrostatic plain bearing
A hydrostatic plain bearing is a type of bearing in which lubricant is pumped between the shaft and bearing by means of a pump. In contrast to hydrodynamic bearings, there is thus permanent full lubrication.
Hydrostatic plain bearings are used when centric running of the shaft is required. However, as the oil supply or oil pressure represents a safety risk, hydrodynamic bearings are often preferred.
Ceramic plain bearing
Ceramic plain bearings made of silicon carbide are often used in pumps. In large pumps, these bearings are often additionally fiber-reinforced. The plain bearings are located in the pump housing and are lubricated with the pumped liquid.
The remarkable corrosion resistance and the extremely low wear due to the hardness are significant advantages of these bearings. However, difficulties can arise if the pumps run dry.
Plastic plain bearing
Plastic plain bearings consist of high-performance polymers and special anti-friction additives. In contrast to metal plain bearings, polymer bearings generally do not require lubricants such as oil or grease for their operation. As a result, they enable lubrication-free and maintenance-free operation. This type of bearing is an environmentally friendly alternative to lubricated metallic plain bearings and offers solid performance, especially under simple to medium operating conditions.
Sintered bearing
Sintered bearings are sintered bushings that are less tight than solid versions. Lubricant can accumulate in their pores (mixed friction). During operation, a lubricating film forms between the bearing and the shaft. Sintered bronze plain bearings are largely resistant to corrosion, have excellent thermal conductivity and are anti-magnetic.
Advantages and disadvantages of plain bearings
Advantages
- Low-noise operation
- Good vibration absorption depending on material
- Very high temperature resistance
- Easy installation
- Long service life at high speeds
Disadvantages
- Heavy wear with solid-state or mixed friction
- Little standardization
- Increased heat generation
- Relatively low load-bearing capacity
Which plain bearing types can HCP Sense monitor?
Similar to rolling bearings, all metallic plain bearings can be fully monitored with our technology due to the associated electrical conductivity, provided that a load-bearing lubricating film or mixed friction forms in the plain bearing.
Ceramic plain bearings are not electrically conductive, but can still be monitored to a limited extent if they are modified.
Plastic plain bearings are usually operated without lubricant, which means that no statement can be made about this. However, it is possible to measure the wear of this type of bearing by means of appropriate modifications, which can prevent unplanned downtime.
Sintered bearings are characterized above all by the fact that they consist of a bushing which is in direct contact with the shaft via a lubricant. Hence, it makes little difference whether the inner ring is a bearing component or the shaft itself, as it is primarily the lubricant in between that provides the decisive information.
You can find more information on how our technology works here:
Your potential benefits - What we can do
The use of HCP Sense technology enables you to:
Lubrication monitoring
- Warning before the occurrence of initial damage
-> Both in case of lubricant shortage and ageing - Prevent failure instead of just predicting it
The following shows a typical curve of the raw data during a machine run-up as part of lubrication monitoring, in which the transition between the different friction ranges is clearly shown:
Service life estimation
- Individual service life of the machine based on actual load
- Improvement of assumptions for future design
- Long warning times based on remaining service life
- Replacement only when “really” needed
These predictive maintenance options are provided to you:
- Prevention of unplanned downtime
- Reduction of the risk of production downtime
- Process monitoring
- Reduction of maintenance costs
- Bearing design
- Insights into user behavior
This results in the following application areas for you:
- Monitoring the load
- RUL forecast based on the load
- Detection of bearing wear
- Preventing bearing failure by monitoring lubrication
- Prevention of unplanned failures
- Condition monitoring of the entire system based on bearing forces (imbalance, alignment, …)
- And much more…!
You can find more information in our tech-corner. You can read more about the causes of bearing damage in our article Bearing damage: Bearing damage: Identify causes early & avoid bearing failure.
Thus, HCP Sense offers reliable predictive maintenance benefits and a very high level of safety for your bearing applications through our condition monitoring!
True to the motto: Increase availability, reduce costs!
We will be more than happy to consult you!
You can find more information about our condition monitoring services under the Products tab.
Call us on +49 172 1805442 if you would like to speak to Dr. Tobias Schirra, our expert in rolling bearing measurement technology.
We are looking forward to hearing from you.
