Super precision bearings
Bearings for screw drives
General features
Design variants
Bearings for screw drives are available as:
- axial angular contact ball bearings
- needle roller/axial cylindrical roller bearings
- for screw mounting
- not for screw mounting
- with accessories
- seal carrier assembly
- precision locknuts
- sockets
- free-of-charge calculation using BEARINX-online Easy Ballscrew
Axial angular contact ball bearings
Bearing design
Precision bearings for screw drive bearing arrangements
Axial angular contact ball bearings are precision bearings for screw drive bearing arrangements. Depending on the series, they can support radial forces as well as axial forces in one or both directions. Contact seals protect the rolling element system against contamination and moisture. For higher speeds, non-contact minimal gap seals can be used.
With and without fixing holes
The bearings are available with and without fixing holes in the outer ring. Bearings with holes are screw mounted directly on the adjacent construction. This solution is particularly economical since there is then no need for the locating bore that would otherwise be required or for the bearing cover with the associated matching work.
Available with less stringent tolerances
For some areas of application, a bearing arrangement of lower precision is often sufficient. For this purpose, bearings with less stringent tolerances are available.
|
Axial angular contact ball bearings, double row, with fixing holes
|
 |
|
Axial angular contact ball bearings, double row, without fixing holes
|
 |
|
Axial angular contact ball bearings, single row, for any combination
|
 |
|
Angular contact ball bearing unit, with fixing holes Lip seals or gap seals ZKLR..-2RS, ZKLR..-2Z |
 |
|
Axial angular contact ball bearings, double or triple row, flange with flattened areas, with fixing holes
|
 |
For special requirements
Screw drive bearing arrangements are subjected to requirements that often cannot be optimally fulfilled by the design construction of conventional bearings.
Wide product range
For the design of bearing arrangements that have high accuracy, high load carrying capacity, high rigidity, low friction, are easy to fit and maintenance-free or low-maintenance and are suitable for the highly dynamic operating conditions of threaded spindles, there is a wide range of INA and FAG axial angular contact ball bearings. With this product range, solutions can be found to all the technical and economic demands placed on the bearing arrangements of feed spindles ➤ link.
Single row and multiple row designs
Axial angular contact ball bearings are available as single, double or triple row ready-to-fit units. They are self-retaining and comprise thick-walled, geometrically stable outer rings, ball and cage assemblies and one-piece or two-piece inner rings. In several series, the outer ring has through holes for simple flange mounting of the bearing to the adjacent construction. The bearing rings are matched to each other such that a defined preload is achieved when the rings are clamped in place using a precision locknut.
Axial and radial load capacity
Due to the 60° contact angle, the bearings can support high axial forces as well as radial forces.
In X or O arrangement
In arrangements of multiple row angular contact ball bearings, a distinction is made between O, X and tandem arrangements in relation to the arrangement of contact angles. The arrangement of contact angles has an essential influence on the tilting rigidity of the bearing position.
The characteristics of the O arrangement are:
- high tilting rigidity
- higher critical whirling speed of the threaded spindle due to the high tilting rigidity of the bearing position
- longer rating life under additional radial loads due, for example, to a belt drive
The characteristics of the X arrangement are:
- low tilting rigidity
- lower critical whirling speed of the threaded spindle
- shorter rating life under additional radial loads due, for example, to a belt drive
X-life premium quality
Axial angular contact ball bearings ZKLF and ZKLN are supplied in the X-life design. As a result of increased raceway accuracy and raceway quality, there is a significant reduction in the stress conditions present on the rolling elements and raceways under the same load, compared to the standard bearings. The improved quality gives reduced friction in the bearing and lower bearing temperatures; running resistance is lower, less strain is placed on the lubricant and the grease operating life and, where applicable, necessary relubrication intervals are extended. As a result of the lower frictional energy, there is a simultaneous increase in the energy efficiency of the bearing arrangement.
Higher basic load ratings and limiting speeds with X-life
The basic dynamic loadi ratings Ca of axial angular contact ball bearings in the X-life design are 10% higher than those of the previous standard designs. This leads to a longer rating life L10 or can be used to allow higher loads on the bearing arrangement while achieving the same rating life. The lower bearing friction and associated reduction in heat generation in the bearing permit significantly higher limiting speeds nG grease.
Temperature range
Limiting values
The operating temperature of the bearings is limited by:
- the dimensional stability of the bearing rings and rolling elements
- the cage
- the lubricant
- the seals
Possible operating temperatures of axial angular contact ball bearings ➤ Table.
Permissible temperature range
|
Operating temperature |
Axial angular contact ball bearings |
|
|---|---|---|
|
from |
to |
|
|
|
–30 °C |
+120 °C |
The operating temperature influences the dynamic bearing characteristics. The values given in the product tables are based on a room temperature of +20 °C.
Cages
The axial angular contact ball bearings have plastic cages. The cage design is not indicated in the suffix.
In axial angular contact ball bearings 7602, 7603 and BSB, the polyamide cages are indicated by the suffix TVP or T.
Suffixes
For a description of the suffixes used in this chapter ➤ Table and medias interchange http://www.schaeffler.de/std/1B69.
Suffixes and corresponding descriptions
|
Suffix |
Description of suffix |
|
|---|---|---|
|
PE |
Bearing design with less stringent tolerances |
Standard |
|
T, TVP |
Polyamide cage |
Standard |
|
2AP |
Axial angular contact ball bearings, |
Standard |
|
2RS |
Contact seal on both sides (lip seal) |
Standard |
|
2Z |
Minimal gap seal on both sides |
Standard |
|
L055 |
Greased with high performance grease |
Standard |
|
SU |
Universal bearing; single bearings can be used |
Standard |
|
HC |
Hybrid Ceramic, rings made from rolling bearing steel, balls made from ceramic |
Special design, available by agreement |
Needle roller/axial cylindrical roller bearings
Bearing design
Double direction
These precision bearings are double direction axial cylindrical roller bearings with a radial bearing component.
With and without fixing holes
The bearings are available with and without fixing holes in the outer ring. Bearings with holes are screw mounted directly on the adjacent construction. The large contact surface and the small pitch of the holes allow a connection to the adjacent construction that is extremely rigid and with low tendency to settling. There is therefore no need for the bearing cover that would otherwise be required to hold the bearing, and the matching work required.
If the axial abutment of the shaft locating washer is not sufficient or a seal raceway is required, bearings with a stepped shaft locating washer extended on one side are suitable.
|
Needle roller/axial cylindrical roller bearings, for screw mounting
|
 |
|
Needle roller/axial cylindrical roller bearings, not for screw mounting
|
 |
Features
Needle roller/axial cylindrical roller bearings comprise an outer ring with radial and axial raceways, shaft locating washers, an inner ring, a radial needle roller and cage assembly and axial cylindrical roller and cage assemblies. The bearings are available with or without fixing holes.
Capable of supporting radial and axial loads
In addition to radial forces, the bearings can also support axial forces from both directions and tilting moments.
Preload and internal clearance
The outer ring, inner ring and axial cages are matched to each other such that the bearing is axially clearance-free after preloading by means of an INA precision locknut. The radial internal clearance Group 2 corresponds to ISO 5753-1 (DIN 620-4).
Bearings for screw mounting
Screw mounting of the outer ring: cover and matching work can be dispensed with
Needle roller/axial cylindrical roller bearings ZARF(-L) have holes in the outer ring. These are used for screw mounting directly on the adjacent construction or in a radial locating bore. Due to screw mounting of the outer ring, the cover that would otherwise be required and the matching work can therefore be dispensed with. The bearings are preloaded against the shaft shoulder by means of a locknut AM or ZM(A).
With seal carrier assembly
In the interests of a simpler design, a seal carrier assembly DRS is recommended. The seal carrier assembly is centred on the outer ring and seals the bearing against external influences.
Bearings not for screw mounting
Mounting in the housing bore
Bearings ZARN(-L) are mounted in the housing bore and the outer ring is located using a cover. They are preloaded against the shaft shoulder by means of a locknut AM or ZM(A).
With stepped shaft locating washer
ZARN/F..-L has a stepped shaft locating washer extended on one side. These series are used in preference where the shaft locating washer is not adequately supported axially by the shaft shoulder or the bearing unit cannot be sealed on the outside surface of the normal shaft locating washer due to space conditions in the adjacent construction.
Heavy series
ZARN/F(-L) is also available in a heavy series. This series has a larger cross-section for the same shaft diameter and therefore higher basic load ratings.
Temperature range
Limiting values
The operating temperature of the bearings is limited by:
- the dimensional stability of the bearing rings and rolling elements
- the lubricant
- the seals
Possible operating temperatures of needle roller/axial cylindrical roller bearings ➤ Table.
Permissible temperature range
|
Operating temperature |
Needle roller/axial cylindrical roller bearings |
|
|---|---|---|
|
from |
to |
|
|
|
–30 °C |
+120 °C |
Suffixes
For a description of the suffixes used in this chapter ➤ Table and medias interchange http://www.schaeffler.de/std/1B69.
Suffixes and corresponding descriptions
|
Suffix |
Description of suffix |
|
|---|---|---|
|
L |
Stepped shaft locating washer extended on one side |
Standard |
|
TVP |
Axial bearing cages made from glass fibre reinforced polyamide PA66 |
Standard |
Accessories
Seal carrier assemblies
Complete sealing sets
Seal carrier assemblies DRS are complete sealing sets ➤ Figure that are screw mounted on the outer ring of needle roller/axial cylindrical roller bearings ZARF(-L). They are precisely centred in this position and seal the bearings against external influences ➤ Figure.
|
Seal carrier assembly DRS |
 |
Components of DRS
The sealing elements are supplied as a complete set of individual parts and comprise:
- a seal flange
- a rotary shaft seal to DIN 3760, with an elastomer part made from NBR
- a gasket
- hexagonal socket head screws for fixing the carrier to the central washer of the bearing
|
Needle roller/axial cylindrical roller bearing ZARF..-L with seal carrier assembly
|
 |
Precision locknuts
Precision locknuts are used in the axial preloading of bearings for screw drives
Precision locknuts are used to achieve a defined axial preload in bearings for screw drives. They are also used where high axial forces must be supported and high axial runout accuracy and rigidity are required.
|
Precision locknuts
|
 |
Sockets
For simple tightening and loosening of precision locknuts ZM on shafts, the sockets LOCKNUT-SOCKET-KM ➤ Figure are suitable. In combination with the socket AMS, this socket is also suitable for precision locknuts AM. They require less space on the circumference of the locknut than hook wrenches and allow the use of torque wrenches.
|
FAG sockets for precision locknuts ZM and sockets AMS
|
 |
Secure sockets using a locking pin and rubber washer
For increased reliability, FAG sockets should be secured using a locking pin and rubber washer. They therefore have a hole for the locking pin and a groove for the rubber washer. The locking pin and rubber washer are included in the scope of delivery.
Super precision bearings
Bearings for screw drives
General features
Design variants
Bearings for screw drives are available as:
- axial angular contact ball bearings
- needle roller/axial cylindrical roller bearings
- for screw mounting
- not for screw mounting
- with accessories
- seal carrier assembly
- precision locknuts
- sockets
- free-of-charge calculation using BEARINX-online Easy Ballscrew
Axial angular contact ball bearings
Bearing design
Precision bearings for screw drive bearing arrangements
Axial angular contact ball bearings are precision bearings for screw drive bearing arrangements. Depending on the series, they can support radial forces as well as axial forces in one or both directions. Contact seals protect the rolling element system against contamination and moisture. For higher speeds, non-contact minimal gap seals can be used.
With and without fixing holes
The bearings are available with and without fixing holes in the outer ring. Bearings with holes are screw mounted directly on the adjacent construction. This solution is particularly economical since there is then no need for the locating bore that would otherwise be required or for the bearing cover with the associated matching work.
Available with less stringent tolerances
For some areas of application, a bearing arrangement of lower precision is often sufficient. For this purpose, bearings with less stringent tolerances are available.
|
Axial angular contact ball bearings, double row, with fixing holes
|
|
|
Axial angular contact ball bearings, double row, without fixing holes
|
|
|
Axial angular contact ball bearings, single row, for any combination
|
|
|
Angular contact ball bearing unit, with fixing holes Lip seals or gap seals ZKLR..-2RS, ZKLR..-2Z |
|
|
Axial angular contact ball bearings, double or triple row, flange with flattened areas, with fixing holes
|
|
For special requirements
Screw drive bearing arrangements are subjected to requirements that often cannot be optimally fulfilled by the design construction of conventional bearings.
Wide product range
For the design of bearing arrangements that have high accuracy, high load carrying capacity, high rigidity, low friction, are easy to fit and maintenance-free or low-maintenance and are suitable for the highly dynamic operating conditions of threaded spindles, there is a wide range of INA and FAG axial angular contact ball bearings. With this product range, solutions can be found to all the technical and economic demands placed on the bearing arrangements of feed spindles ➤ link.
Single row and multiple row designs
Axial angular contact ball bearings are available as single, double or triple row ready-to-fit units. They are self-retaining and comprise thick-walled, geometrically stable outer rings, ball and cage assemblies and one-piece or two-piece inner rings. In several series, the outer ring has through holes for simple flange mounting of the bearing to the adjacent construction. The bearing rings are matched to each other such that a defined preload is achieved when the rings are clamped in place using a precision locknut.
Axial and radial load capacity
Due to the 60° contact angle, the bearings can support high axial forces as well as radial forces.
In X or O arrangement
In arrangements of multiple row angular contact ball bearings, a distinction is made between O, X and tandem arrangements in relation to the arrangement of contact angles. The arrangement of contact angles has an essential influence on the tilting rigidity of the bearing position.
The characteristics of the O arrangement are:
- high tilting rigidity
- higher critical whirling speed of the threaded spindle due to the high tilting rigidity of the bearing position
- longer rating life under additional radial loads due, for example, to a belt drive
The characteristics of the X arrangement are:
- low tilting rigidity
- lower critical whirling speed of the threaded spindle
- shorter rating life under additional radial loads due, for example, to a belt drive
X-life premium quality
Axial angular contact ball bearings ZKLF and ZKLN are supplied in the X-life design. As a result of increased raceway accuracy and raceway quality, there is a significant reduction in the stress conditions present on the rolling elements and raceways under the same load, compared to the standard bearings. The improved quality gives reduced friction in the bearing and lower bearing temperatures; running resistance is lower, less strain is placed on the lubricant and the grease operating life and, where applicable, necessary relubrication intervals are extended. As a result of the lower frictional energy, there is a simultaneous increase in the energy efficiency of the bearing arrangement.
Higher basic load ratings and limiting speeds with X-life
The basic dynamic loadi ratings Ca of axial angular contact ball bearings in the X-life design are 10% higher than those of the previous standard designs. This leads to a longer rating life L10 or can be used to allow higher loads on the bearing arrangement while achieving the same rating life. The lower bearing friction and associated reduction in heat generation in the bearing permit significantly higher limiting speeds nG grease.
Temperature range
Limiting values
The operating temperature of the bearings is limited by:
- the dimensional stability of the bearing rings and rolling elements
- the cage
- the lubricant
- the seals
Possible operating temperatures of axial angular contact ball bearings ➤ Table.
Permissible temperature range
|
Operating temperature |
Axial angular contact ball bearings |
|
|---|---|---|
|
from |
to |
|
|
|
–30 °C |
+120 °C |
The operating temperature influences the dynamic bearing characteristics. The values given in the product tables are based on a room temperature of +20 °C.
Cages
The axial angular contact ball bearings have plastic cages. The cage design is not indicated in the suffix.
In axial angular contact ball bearings 7602, 7603 and BSB, the polyamide cages are indicated by the suffix TVP or T.
Suffixes
For a description of the suffixes used in this chapter ➤ Table and medias interchange http://www.schaeffler.de/std/1B69.
Suffixes and corresponding descriptions
|
Suffix |
Description of suffix |
|
|---|---|---|
|
PE |
Bearing design with less stringent tolerances |
Standard |
|
T, TVP |
Polyamide cage |
Standard |
|
2AP |
Axial angular contact ball bearings, |
Standard |
|
2RS |
Contact seal on both sides (lip seal) |
Standard |
|
2Z |
Minimal gap seal on both sides |
Standard |
|
L055 |
Greased with high performance grease |
Standard |
|
SU |
Universal bearing; single bearings can be used |
Standard |
|
HC |
Hybrid Ceramic, rings made from rolling bearing steel, balls made from ceramic |
Special design, available by agreement |
Needle roller/axial cylindrical roller bearings
Bearing design
Double direction
These precision bearings are double direction axial cylindrical roller bearings with a radial bearing component.
With and without fixing holes
The bearings are available with and without fixing holes in the outer ring. Bearings with holes are screw mounted directly on the adjacent construction. The large contact surface and the small pitch of the holes allow a connection to the adjacent construction that is extremely rigid and with low tendency to settling. There is therefore no need for the bearing cover that would otherwise be required to hold the bearing, and the matching work required.
If the axial abutment of the shaft locating washer is not sufficient or a seal raceway is required, bearings with a stepped shaft locating washer extended on one side are suitable.
|
Needle roller/axial cylindrical roller bearings, for screw mounting
|
|
|
Needle roller/axial cylindrical roller bearings, not for screw mounting
|
|
Features
Needle roller/axial cylindrical roller bearings comprise an outer ring with radial and axial raceways, shaft locating washers, an inner ring, a radial needle roller and cage assembly and axial cylindrical roller and cage assemblies. The bearings are available with or without fixing holes.
Capable of supporting radial and axial loads
In addition to radial forces, the bearings can also support axial forces from both directions and tilting moments.
Preload and internal clearance
The outer ring, inner ring and axial cages are matched to each other such that the bearing is axially clearance-free after preloading by means of an INA precision locknut. The radial internal clearance Group 2 corresponds to ISO 5753-1 (DIN 620-4).
Bearings for screw mounting
Screw mounting of the outer ring: cover and matching work can be dispensed with
Needle roller/axial cylindrical roller bearings ZARF(-L) have holes in the outer ring. These are used for screw mounting directly on the adjacent construction or in a radial locating bore. Due to screw mounting of the outer ring, the cover that would otherwise be required and the matching work can therefore be dispensed with. The bearings are preloaded against the shaft shoulder by means of a locknut AM or ZM(A).
With seal carrier assembly
In the interests of a simpler design, a seal carrier assembly DRS is recommended. The seal carrier assembly is centred on the outer ring and seals the bearing against external influences.
Bearings not for screw mounting
Mounting in the housing bore
Bearings ZARN(-L) are mounted in the housing bore and the outer ring is located using a cover. They are preloaded against the shaft shoulder by means of a locknut AM or ZM(A).
With stepped shaft locating washer
ZARN/F..-L has a stepped shaft locating washer extended on one side. These series are used in preference where the shaft locating washer is not adequately supported axially by the shaft shoulder or the bearing unit cannot be sealed on the outside surface of the normal shaft locating washer due to space conditions in the adjacent construction.
Heavy series
ZARN/F(-L) is also available in a heavy series. This series has a larger cross-section for the same shaft diameter and therefore higher basic load ratings.
Temperature range
Limiting values
The operating temperature of the bearings is limited by:
- the dimensional stability of the bearing rings and rolling elements
- the lubricant
- the seals
Possible operating temperatures of needle roller/axial cylindrical roller bearings ➤ Table.
Permissible temperature range
|
Operating temperature |
Needle roller/axial cylindrical roller bearings |
|
|---|---|---|
|
from |
to |
|
|
|
–30 °C |
+120 °C |
Suffixes
For a description of the suffixes used in this chapter ➤ Table and medias interchange http://www.schaeffler.de/std/1B69.
Suffixes and corresponding descriptions
|
Suffix |
Description of suffix |
|
|---|---|---|
|
L |
Stepped shaft locating washer extended on one side |
Standard |
|
TVP |
Axial bearing cages made from glass fibre reinforced polyamide PA66 |
Standard |
Accessories
Seal carrier assemblies
Complete sealing sets
Seal carrier assemblies DRS are complete sealing sets ➤ Figure that are screw mounted on the outer ring of needle roller/axial cylindrical roller bearings ZARF(-L). They are precisely centred in this position and seal the bearings against external influences ➤ Figure.
|
Seal carrier assembly DRS |
|
Components of DRS
The sealing elements are supplied as a complete set of individual parts and comprise:
- a seal flange
- a rotary shaft seal to DIN 3760, with an elastomer part made from NBR
- a gasket
- hexagonal socket head screws for fixing the carrier to the central washer of the bearing
|
Needle roller/axial cylindrical roller bearing ZARF..-L with seal carrier assembly
|
|
Precision locknuts
Precision locknuts are used in the axial preloading of bearings for screw drives
Precision locknuts are used to achieve a defined axial preload in bearings for screw drives. They are also used where high axial forces must be supported and high axial runout accuracy and rigidity are required.
|
Precision locknuts
|
|
Sockets
For simple tightening and loosening of precision locknuts ZM on shafts, the sockets LOCKNUT-SOCKET-KM ➤ Figure are suitable. In combination with the socket AMS, this socket is also suitable for precision locknuts AM. They require less space on the circumference of the locknut than hook wrenches and allow the use of torque wrenches.
|
FAG sockets for precision locknuts ZM and sockets AMS
|
|
Secure sockets using a locking pin and rubber washer
For increased reliability, FAG sockets should be secured using a locking pin and rubber washer. They therefore have a hole for the locking pin and a groove for the rubber washer. The locking pin and rubber washer are included in the scope of delivery.