The right bearing choices for diverse industrial applications can result in increased performance and efficiency, while significantly reducing downtime and maintenance costs. Bearings are not 'one-size-fits-all' products.
Selection criteria
Factors to be considered in bearing selection include:
* Bearing type.
* Precision and speed requirements.
* Dimensions.
* Design and suitability of associated components (shaft and housing).
* Magnitude and direction of applied loads (radial, axial or both).
* Holding devices.
* Adequacy of seals (to resist ingress of contamination).
* Type and quality of lubricant.
* Ease of installation and removal for maintenance purposes.
Each decision affects the performance, reliability and economy of the bearing arrangement and ultimately, the machine in which it is to be used.
Deep groove ball bearings
These bearings accommodate radial and axial loads. They are well suited to use in small and medium-sized electric motors and centrifugal pumps. These ball bearings are available with either metal or polyamide cages, and with or without seals or shields. The sealed versions use integral nitrile rubber or synthetic seals to protect the bearing from contaminants and retain the lubricant. The range of greases used are typically formulated with anti-corrosion additives and designed to withstand a wide range of operating temperatures.
Taper roller bearings
These are suitable for higher load applications where space is limited. They are for use in equipment with combined radial and axial loads. The increased dynamic load carrying capacity of the taper roller bearing makes it possible to either reduce the size of the bearing units or to increase the strength and performance of existing assemblies. In other words, identical performance can be achieved with a more compact design and improved power density. Smaller bearings offer reduced friction, lower operating temperatures, noise and vibration levels.
Spherical roller and CARB toroidal roller bearings
These bearing types are ideal for heavy engineering applications where heavy loads, shaft deflections and misalignments are common. SKF's spherical plain bearings, with integral triple lip seal and PTFE fabric liner, give maintenance-free operation over extended operating lives and provide long service life with minimal maintenance for heavy industry equipment. The bearings offer superior resistance to wear, higher load carrying capacity, higher bearing stiffness and lower frictional characteristics when compared to regular plain bearings, making them ideally suited to high load applications with slow rotational speeds.
Seals
Specifying the correct type of seal is also crucial. Bearings and seals form a complete system, with different seals available in many designs and in different materials to complement various bearing designs.
Factors that influence the choice of seal include:
* Type of lubrication.
* Sliding velocity at the counterface.
* Orientation (seal mounted vertically or horizontally).
* Shaft misalignment.
* Operating temperature.
Research conducted by SKF shows that up to 14% of all premature bearing failures can be directly attributed to contaminants entering bearings via poorly designed or incorrectly specified seals, or because the materials used were unsuitable for a specific application - further proof that it is crucial to specify the correct seal type.
For more information contact Sarel Froneman, SKF South Africa, +27 (0)11 821 3500, [email protected], www.skf.co.za
| Tel: | +27 11 821 3500 |
| Fax: | +27 11 821 3501 |
| Email: | [email protected] |
| www: | www.skf.co.za |
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