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Plain bearing wiki

We have summarised all the important technical issues relating to our plain bearings here. Find out more about our plain bearing materials and their specification. There are also important tips for the use of iglidur® plain bearings and expertise from practice and research which we make available to you free of charge in our whitepapers.

What you will find on this page

What is iglidur®?Comparison of different types of bearingsInstallation and tolerancesWhat is the stick-slip effect?What does the PV value signify?Test laboratory and resultsfavoriteTop iglidur® materialsShop bearingsbuildTo the configurators
Plain bearings under scrutiny

What is iglidur®?

iglidur® are materials developed by igus. They consist of high-performance polymers and are characterised by special specifications. For example, they are particularly wear-resistant or suitable for contact with media and chemicals.

But what are iglidur materials made of? And what is behind the self-lubricating effect? Find out more about the specification and composition of iglidur bearings.

Learn more about our materials
A comparison of different bearing types

Comparison of different bearing types

There are various bearing types to choose from when selecting the right plain bearing. Each has a different design and its own mode of operation. We have summarised the most important bearing types for you and show you what advantages they have.

Comparing different bearing types
Shaft

Choosing the right shaft material

The right choice of shaft and plain bearing plays a decisive role in a well-functioning bearing system. Plain bearings protect the often significantly more expensive drive shaft and the components surrounding the bearing point from wear. It is therefore particularly important that this wear only occurs in the plain bearing and that it is replaced in good time. However, the shaft is often neglected when designing the bearing position. Find out how to correctly match the two components to each other.

More about harmonising plain bearings and shafts
Plain bearing installation

Installation and tolerances

When installing plain bearings, there are a few things to bear in mind that are crucial for fault-free operation and a long service life. Find out everything you need to know about suitable installation and testing methods, clearance design, standard tolerances and the correct securing of plain bearings.

To the installation recommendations

"Stick-slip effect"

stick slip image

The stick–slip effect describes intermittent, erratic motion between two contacting surfaces when the coefficient of static friction (μₛ) is significantly higher than the coefficient of kinetic (sliding) friction (μₖ).

Motion begins once the applied force exceeds the maximum static friction. As sliding starts, friction drops causing sudden acceleration. If the driving force then becomes insufficient to sustain this motion, the system decelerates and becomes static. This transition cycle between static adhesion (“stick”) and dynamic sliding (“slip”) produces rapid oscillations in velocity, which can be perceived as a vibration or stutter.

What does the pv value mean?

PV value

The product of the specific load [p] and the surface speed [v] is of particular importance for plain bearings. The pv value can be regarded as a measure of frictional heat and therefore be used as an analytical tool to check a plain bearing's suitability. For this purpose, the actual pv value is compared with a predictable permitted pv value. The permitted pv value depends on the shaft material, the ambient temperature and the duty cycle.

pv value graph

In these equations:

  • K1. K2 = Constant for heat dissipation (K1 = 0.5, K2 = 0.042)
  • Øs = Bearing wall thickness, mm
  • b1 = Bearing length [mm] [mm]
  • μ = Coefficient of friction
  • λs = Thermal conductivity of the shaft
  • λk = Thermal conductivity of the bearing
  • ΔT = (Ta - Tu)
  • Tu = Ambient temperature
  • Ta = Max. Application temperature
graph

Correction Factor

The permitted pv value can be increased in intermittent operation if the bearing temperature does not reach the maximum at all due to the short run time. Tests have shown that this is the case with run times below 10 minutes. The shorter the run time, the lower the maximum bearing temperature reached.
An important factor here is the ratio of duty cycle and pauses. It is obvious that long pauses contribute more to re-cooling. The different curves in Diagram 09 represent the different ratios (three times means that the pause lasts three times longer than the run time).

  • Dry operation = correction factor 1
  • During installation = correction factor 1.3
  • Continuous, grease = correction factor 2
  • Continuous, water = correction factor 4
  • Continuous, oil = correction factor 5
Coolant pump with hydrodynamic plain bearings

What are hydrodynamic and hydrostatic plain bearings?

What are hydrodynamic and hydrostatic plain bearings? How do these two bearing types work, what are their advantages and what are their typical areas of application? Answers to these questions can be found here.

Learn more about hydrodynamic and hydrostatic plain bearings

Largest test laboratory in the industry

igus employee in test lab

What and how is tested?

In the iglidur test area, bearings and materials are tested for stress, wear and friction properties. Other parameters such as high and low temperatures, high load and speed are adjusted depending on the test. There are around 50 test systems in the test laboratory, on which more than 300 parallel tests are carried out. At the same time, we carry out around 11,300 tribological tests on the 250 or so newly developed plastic compounds every year. To ensure that the new formulations prove themselves in later use, they are not only exposed to external influences, but also to different directions of movement and loads - rotating, swivelling, linear, walking.

Plain bearing press fit

Results from the igus test laboratory

Avoid reduced press fit due to anti-corrosion agent
The use of anti-corrosion agents in the bearing mount can reduce the firmness of the bearing's fit. Find out what anti-corrosion agent increases firmness instead.

  • Learn more
    • Shafts in the salt spray test

    Results from the igus test laboratory

    How well does gas-nitrocarburisation protect shafts from corrosion?
    We have investigated what surface treatment best protects shafts from corrosion. Shafts were fitted with iglidur plain bearings and subjected to a 120-hour salt spray test.

  • Learn more
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