Sunday, July 12, 2009
Principles of bearing selection and application
A bearing arrangement does not only consist of rolling bearings but includes the components associated with the bearings such as the shaft and housing.
The lubricant is also a very important component of the bearing arrangement because it has to prevent wear and protect against corrosion so that the bearing can deploy its full performance.
Beside these, the seal is also a very important component, the performance of which is of vital importance to the cleanliness of the lubricant. Cleanliness has a profound effect on bearing service life - which is why lubricants and seals have become part of the Bearing selection process.
To design a rolling bearing arrangement it is necessary
1. to select a suitable bearing type
2. to determine a suitable bearing size,but this is not all. Several other aspects have to
be considered, such as
1. A suitable form and design of other components of the arrangement
2. appropriate fits and bearing internal clearance or preload
3. holding devices
4. adequate seals
5. the type and quantity of lubricant
6. installation and removal methods, etc.
Each individual decision affects the performance, reliability and economy of the bearing arrangement.
Radial Bearings
Some important parameters you must consider before purchasing a radial bearing are:
Radial bearings are useful for applications in which high radial loads act on the components. These bearing can also sustain moderate thrust loads and combinations of thrust and radial loads. Radial bearings are useful in various industries such as food and beverage, automotive and textile.
You can use a radial ball bearing or a radial roller bearing made of plastic or metal depending on the operating conditions. Important components of a radial bearing are balls or rollers, rings, retainers and seals or shields. Like other bearings, bearing lubricant is necessary for the efficient operation of a radial bearing.
1. Loads acting on the radial bearing
2. Rotating speed of the bearing
3. Dimensions of a radial bearing: outer diameter, inside diameter and width
4. Average fatigue life of the radial bearing
5. Operating temperature ranges for the radial bearing
Roller Bearings
Some important parameters you must consider before purchasing a roller bearing are:
You can use roller bearings for heavy-duty applications with moderate rotating speeds.
Typical applications of roller bearings include power generation equipment, oil pumps, mining instruments, gear drives and rolling mills.
Depending on the shape of the roller, manufacturers specify the roller bearing as a cylindrical roller bearing, spherical roller bearing or tapered roller bearing,needle roller bearing. Additionally, manufacturers also classify roller bearings based on their required load capacity. Depending on the load carrying capacity, you can select a single row roller bearing, a double row roller bearing or a multiple row roller bearing.
1. Loads acting on the roller bearing
2. Operating speed of the roller bearing
3. Average fatigue life of the roller bearing
4. Type of roller bearing
5. Dimensions of the roller bearing: outer diameter, inner diameter and width
The lubricant is also a very important component of the bearing arrangement because it has to prevent wear and protect against corrosion so that the bearing can deploy its full performance.
Beside these, the seal is also a very important component, the performance of which is of vital importance to the cleanliness of the lubricant. Cleanliness has a profound effect on bearing service life - which is why lubricants and seals have become part of the Bearing selection process.
To design a rolling bearing arrangement it is necessary
1. to select a suitable bearing type
2. to determine a suitable bearing size,but this is not all. Several other aspects have to
be considered, such as
1. A suitable form and design of other components of the arrangement
2. appropriate fits and bearing internal clearance or preload
3. holding devices
4. adequate seals
5. the type and quantity of lubricant
6. installation and removal methods, etc.
Each individual decision affects the performance, reliability and economy of the bearing arrangement.
Radial Bearings
Some important parameters you must consider before purchasing a radial bearing are:
Radial bearings are useful for applications in which high radial loads act on the components. These bearing can also sustain moderate thrust loads and combinations of thrust and radial loads. Radial bearings are useful in various industries such as food and beverage, automotive and textile.
You can use a radial ball bearing or a radial roller bearing made of plastic or metal depending on the operating conditions. Important components of a radial bearing are balls or rollers, rings, retainers and seals or shields. Like other bearings, bearing lubricant is necessary for the efficient operation of a radial bearing.
1. Loads acting on the radial bearing
2. Rotating speed of the bearing
3. Dimensions of a radial bearing: outer diameter, inside diameter and width
4. Average fatigue life of the radial bearing
5. Operating temperature ranges for the radial bearing
Roller Bearings
Some important parameters you must consider before purchasing a roller bearing are:
You can use roller bearings for heavy-duty applications with moderate rotating speeds.
Typical applications of roller bearings include power generation equipment, oil pumps, mining instruments, gear drives and rolling mills.
Depending on the shape of the roller, manufacturers specify the roller bearing as a cylindrical roller bearing, spherical roller bearing or tapered roller bearing,needle roller bearing. Additionally, manufacturers also classify roller bearings based on their required load capacity. Depending on the load carrying capacity, you can select a single row roller bearing, a double row roller bearing or a multiple row roller bearing.
1. Loads acting on the roller bearing
2. Operating speed of the roller bearing
3. Average fatigue life of the roller bearing
4. Type of roller bearing
5. Dimensions of the roller bearing: outer diameter, inner diameter and width
DIMENSIONING & TOLERANCING
MANUFACTURING
1.Product involves assembly of parts.
2. Variability in dimensions (height, width,
depth, diameter, angle etc) of parts
manufactured -- due to variety of
reasons, some controllable and others not
3. This has implications for assembly of
parts.
In order to over come this practical situation
We need a DIMENSIONAL TOLERANCE
1. Is defined as the permissible or
acceptable variation in dimensions of a
part.
2. Tolerance is unavoidable as it is
impossible (and unnecessary) to
manufacture two parts that have
precisely the same dimensions.
TOLERANCE
1. Close tolerances implies precision
manufacturing and increases the cost of
production.
2. Hence the need for proper tolerance
based on product functionality.
SIMPLE ASSEMBLY
• HOLE and SHAFT
• TYPE OF FIT [Illustrative sample]
– Loose fit
– Free fit
– Snug fit
– Tight fit
– Medium force fit
– Heavy force shrink fit
IMPLICATIONS
1. If the fit is not OK the part might need
either rework or be scrapped.
2. Increases the cost of manufacturing.
3. Hence need to determine the economic
manufacturing tolerance while ensuring
functionality.
DEFINITIONS
1. Dimension:
A characteristic such as
length, angle, or diameter for which
magnitude is specified in the appropriate
unit of measurement.
2. Tolerance:
The total amount of variation
permitted for the size of a dimension, a
positional relationship or other design
requirement.
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1.Product involves assembly of parts.
2. Variability in dimensions (height, width,
depth, diameter, angle etc) of parts
manufactured -- due to variety of
reasons, some controllable and others not
3. This has implications for assembly of
parts.
In order to over come this practical situation
We need a DIMENSIONAL TOLERANCE
1. Is defined as the permissible or
acceptable variation in dimensions of a
part.
2. Tolerance is unavoidable as it is
impossible (and unnecessary) to
manufacture two parts that have
precisely the same dimensions.
TOLERANCE
1. Close tolerances implies precision
manufacturing and increases the cost of
production.
2. Hence the need for proper tolerance
based on product functionality.
SIMPLE ASSEMBLY
• HOLE and SHAFT
• TYPE OF FIT [Illustrative sample]
– Loose fit
– Free fit
– Snug fit
– Tight fit
– Medium force fit
– Heavy force shrink fit
IMPLICATIONS
1. If the fit is not OK the part might need
either rework or be scrapped.
2. Increases the cost of manufacturing.
3. Hence need to determine the economic
manufacturing tolerance while ensuring
functionality.
DEFINITIONS
1. Dimension:
A characteristic such as
length, angle, or diameter for which
magnitude is specified in the appropriate
unit of measurement.
2. Tolerance:
The total amount of variation
permitted for the size of a dimension, a
positional relationship or other design
requirement.
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