The sleeve bearing is a component for which the phrase “simple yet effective” was coined. Why? Because a sleeve bearing allows for the linear or rotational movement of two pieces.
The sliding action of a sleeve bearing differs from the rolling action of a ball or roller bearing. Bushings, plain sleeve bearing types, and journal bearings are other names. They can be used with lubricants or self-lubricating components to provide smooth, continuous functioning.
When lubricated, sleeve bearings have a low friction coefficient and great wear resistance. Sleeve bearings are widely utilized in various applications due to their inexpensive cost and lack of maintenance.
A detailed explanation of Sleeve Bearing
Sleeve bearings are a straightforward and affordable design widely used in rotating machines. These fixed geometry bearings are available in various designs to meet the load capacity, rotational load, stiffness, damping, and stability application needs (resistance to whirl).
While modifications to the circular geometry increase stability even more, the inclusion of grooves can lessen the destabilizing effects of fluid rotation. The number of lobes, bearing material, lubrication, and lobe geometry are design factors that can be used to enhance performance. Lubrication may be self-lubricating or pressure-fed, usually utilizing an oil ring.
There are various different features for sleeve bearings.
- Bearings that are self-lubricating or that are impregnated with oil don’t need any additional lubrication. Oil can be used to impregnate sintered bronze. The idea behind self-lubricating bearings is that a modest quantity of material transferred from the bearing layer will result in the formation of a solid lubricating coating during the initial run-in period of the bearing.
- Direct contact between the film and the moving parts shields the mating portion from damage, extending the bearing’s useful life. Safe and effective bearing operation depends on proper lubrication. A lack of lubrication can cause equipment malfunctions and rapid material deterioration.
- Extreme weather conditions, such as high or low temperatures, humidity, shock, and vibration, call for bearings that are trustworthy, long-lasting, and composed of a substance that can survive the worst conditions. It is also important to take into account the entire range of ambient operating temperatures, including daily temps.
- The gap between the bushing and the housing or the bushing and the shaft may change when the temperature varies. The bushing may experience severe wear and have a shorter lifespan if the distance gets too close.
Difference between a sleeve bearing and a bushing
A bushing is a tube or sleeve that allows linear or rotational movement, just like a sleeve bearing. Both terms are interchangeable. Bushings are defined by their style: sleeve bearing, plain bearing, journal bearing, and sliding bearing. A bushing is always a bearing, but not all bearings are bushings, as we explain in our blog, A Guide to Bearings and Bushings.
The function of a sleeve bearing
Sleeve bearings allow motion between two components while reducing friction and absorbing vibration. Because of their large load capacity, they are appropriate for a wide range of heavy-duty applications. Robust rotor sleeve bearings can withstand high loads and temperatures while exhibiting little wear. Their contact area is highly resistant to shock loads, and they can compensate for the misalignment of the other components. They have several advantages, including reduced friction, compactness, system size, light weights, ease of installation, and vibration reduction.
Advantages of Sleeve Bearings
There are several advantages to employing Sleeve Bearings. Our engineers can select the best material for each application due to the unique material structure and combinations. A thick PTFE sliding layer for misalignment adjustment, a consistent coefficient of friction, and reduced NVH are all options. Metal as a backing material provides great load capabilities and can be improved for corrosion resistance if necessary.
Where do sleeve bearings come into play?
Sleeve bearings are highly adaptable and can be utilized in various applications. They can be used to facilitate several types of movement:
- Rotational movements
- Linear movements
- Oscillating movements with a high frequency
Because they are typically found in pivot points, they are widely employed in the automobile industry, manufacturing machines, and white goods. They provide rotating linear movement for hinges, seat adjustment mechanisms, and steering yokes in the car sector. For high-frequency oscillating movement, belt tensioners use sleeve bearings. Lift and tilt devices require them to permit linear movement; clevis joints for hydraulic cylinder pins are another example.
Types, designs, and materials for sleeve bearings
There are several basic types of sleeve bearings and various material alternatives. Sleeve bearings are all one-piece designs, with the flanged sleeve bearing being the most popular. A flanged sleeve bearing may accommodate both axial and radial loads. A combination of a thrust washer and a cylindrical bearing is an excellent option for larger side loads. Choose a basic cylindrical bearing if the load is solely radial.
Bearings are available in a variety of materials. Among them are metal, bimetal, ceramic, stone, graphite, composites, and plastic. The material used to make the sleeve bearing determines its strength, elasticity, coefficient of friction, and other properties.
When used with strong steel shafts, cast or sintered metal bushings have a low coefficient of friction under hydrodynamic circumstances, but the intense rattling eliminates many applications. Molded plastic is a low-cost solution in various shapes and sizes; however, plastic bearings have restrictions.
Sleeve bearings that self-lubricate
A compound layer must be added to make sleeve bearings self-lubricating. It promotes smooth functioning and extends the life of the bushing. External lubricant can occasionally help with wear and friction. Additional grooves within the surface can serve as lubricant reservoirs in this case.
Sleeve Bearing Repair
There are numerous sleeve-bearing fixable problems. For instance, we were talking about bearing clearances. Some problems with vibration or insufficient lubrication can be resolved by adjusting the clearance between the shaft and bearing. In some cases, the bearing housing design may need to be altered, the Babbitt material may need to be changed, or the surface may need to be updated. The process known as spin casting or centrifugal casting is used to replace this Babbitt substance.
Since lubrication plays a crucial role in how long a bearing will live, correcting a lack of lubrication will often cure bearing problems. Adjusting to oil rings and distribution grooves, as well as adjusting the kind of lubrication (viz., viscosity, additives), may be necessary to achieve this. Guides and wipers can also be built into the bearing to aid in better oil distribution. An end seal and a drain groove can be installed if oil recovery is a problem.
Since faulty oil seals are the main cause of lubrication leakage, in some cases, a different seal shape may be advised. Labyrinth seals appear to function best with sleeve bearings, but selecting the best one for your application depends on several factors.
Ball and sleeve bearings may also be damaged due to electrical problems. Circulating currents in electric motor shafts cause this kind of damage.
Sleeve bearings, bushings, and linear bush bearings are some important elements of all industries. Most industry owners are searching for these kinds of products, and if you are one of them, do contact the experts at MicroCare Group. MicroCare Group’s team is always there to help you with any industry component issue.
When adequate lubrication and clearances are involved, bearing problems can be fairly difficult. The good news is that many problems can be fixed, and specialists can help direct you through the process. Remember that MicroCare Group is an EASA-accredited repair facility with the expertise and knowledge to help you get the most out of your sleeve bearings if you are experiencing bearing problems.