YRT Roatry Table Bearing

Axial/radial bearings

Axial/radial bearings are double direction axial bearings for screw mounting, with a radial guidance bearing. These ready-to-fit,greased units are very rigid, have high load carrying capacity and run with particularly high accuracy. They can support radial forces, axial forces from both directions and tilting moments free from clearance. The bearings are available in several series. For applications with low speeds and small operating durations, such as indexing tables and swivel type milling heads, the most suitable bearings are generally series YRT and YRTC.

For the bearing arrangements of direct drive axes, there is the series YRTS. Due to their high limiting speeds and very low, uniform frictional torque across the whole speed range, these bearings are particularly suitable for combination with torque motors. For higher accuracy requirements, these bearings are also available with restricted axial and radial runout accuracy.

Axial angular contact ball bearings

Axial angular contact ball bearings ZKLDF are low-friction, ready-to-fit, pregreased bearing units with high accuracy for very high speeds, high axial and radial loads and high demands on

tilting rigidity.Axial angular contact ball bearings are particularly suitablefor precision applications involving combined loads. Their preferred areas of use are bearing arrangements in rotary tables with a main

spindle function, for example in combined milling and turning, as well as in milling, grinding and honing heads and in measurement and testing equipment.

Axial/radial bearings with angular measuring system

Axial/radial bearings with angular measuring system YRTM and YRTSM correspond in mechanical terms to series YRT and YRTS, but are additionally fitted with an angular measuring system. The measuring system can measure angles to an accuracy of a few angular seconds by non-contact, magneto-resistive means.

Further information on axial/radial bearings with absolute value angular measuring systems YRTMA and YRTSMA can be found in special publication SSD 30.

Features 

Axial radial bearings YRT, YRTC and YRTS and axial angular contact ball bearings ZKLDF are ready-to-fit high precision bearings for high precision applications with combined loads. They can support radial loads, axial loads from both sides and tilting moments without clearance and are particularly suitable for bearing arrangements with high requirements for running accuracy.

Due to the fixing holes in the bearing rings, the units are very easy to fit.

The bearings are radially and axially preloaded after fitting.

The mounting dimensions of all series are identical.

Axial/radial bearings YRT in the size range of d = 580 mm to d = 1 030 mm have been replaced by YRTC.

Compared with the predecessor product YRT, these bearings have higher rigidity, a higher limiting speed and lower bearing friction.

With angular measuring system 

Axial/radial bearings are also available with an absolute value angular measuring system or have systems with pitch-coded reference marks. The measuring systems can measure angles to an accuracy of a few angular seconds by non-contact means.

Areas of application For standard applications with low speeds and small operatingdurations, such as indexing tables and swivel type milling heads, the most suitable bearings are generally series YRT and YRTC.

For the bearing arrangements of direct drive axes, there is the series YRTS. Due to their high limiting speeds and very low, uniform frictional torque across the whole speed range, these bearings are

particularly suitable for combination with torque motors.

For higher accuracy requirements, these bearings are also available with restricted axial and radial runout accuracy.

Axial angular contact ball bearings ZKLDF are particularly suitable for high speed applications with long operating duration.

They are characterised by high tilting rigidity, low friction and low lubricant consumption.

Axial/radial bearings 

Axial/radial bearings YRT, YRTC and YRTS have an axial and a radial component.

The axial component comprises an axial needle roller or cylindrical roller and cage assembly, an outer ring, L-section ring and shaft locating washer and is axially preloaded after fitting. The radial

component is a full complement cylindrical roller set in YRT and a cage-guided, preloaded cylindrical roller set in YRTC and YRTS.

The outer ring, L-section ring and shaft locating washer have fixing holes. The unit is located by means of retaining screws for transport and safe handling.

Sealing 

Axial/radial bearings are supplied without seals.

Lubrication 

The initial greasing of YRTS corresponds to the grease Arcanol LOAD150 and, in the case of YRT and YRTC, to the grease Arcanol MULTITOP. The bearings can be lubricated via the outer ring and 

L-section ring.

Axial angular contact ball bearings

Axial angular contact ball bearings ZKLDF comprise a single-piece outer ring, a two-piece inner ring and two ball and cage assemblies with a contact angle of 60°. The outer ring and inner ring have fixing holes for screw mounting of the bearing on the adjacent construction.

The unit is located by means of retaining screws for transport and safe handling.

Sealing 

Axial angular contact ball bearings have sealing shields on both sides.

Lubrication 

The initial greasing of current axial angular contact ball bearings ZKLDF (Generation B) corresponds to the grease Arcanol MULTITOP. The bearings can be relubricated via the outer ring.

Operating temperature 

Axial/radial bearings and axial angular contact ball bearings are suitable for operating temperatures from –30 °C to +120 °C.

Available designs

Design andsafety guidelines

General safety guidelines The general safety guidelines must be observed. Further information relating to safety of control circuits: see Axial/radial bearings with angular measuring system.

Basic rating life 

The load carrying capacity and life must be checked for the radial andaxial bearing component.

Please contact us in relation to checking of the basic rating life.

The speed, load and operating duration must be given.

Limiting speeds 

In bearing selection, the following guidelines and the limiting speeds must be observed, see dimension tables.

If the environmental conditions differ from the specifications in relation to adjacent construction tolerances, lubrication, ambient temperature, heat dissipation or from the normal operating conditions for machine tools, the stated limiting speeds must be checked. Please contact us.

Axial/radial bearing YRT 

Axial/radial bearings YRT are designed, by means of the full complement radial roller bearing component for high rigidity, for rapid positioning and operating at low speed. Low speeds are normally required for multiple-axis simultaneous machining.

The limit value nG stated in the dimension tables relates to the maximum swivel speed and a maximum speed applied for a short period.

Axial radial bearings YRTC, YRTS and ZKLDF axial angular contact ball bearings

The limiting speeds nG stated for these bearing series were determined on test rigs.

During the test, the following conditions apply:

grease distribution cycle according to the defined data,

maximum increase in bearing temperature of 40 K in the areaof the raceway

operating duration ED = 100%, which means continuous operation at the limiting speed nG

bearing fully screw mounted on solid fixtures

no external load, only preload and mass of the fixtures.

Temperature distribution in the rotary axis system

Rotary axes with a main spindle function, such as those used for combined milling and turning and with direct drive by a torque motor, are systems with complex thermal characteristics.

The temperature distribution in the rotary axis system must be considered in greater detail during the design process:

Asymmetrical rotary axis housings can undergo asymmetrical deformation due to heating.

In turn, out-of-round bearing seats lead to additional bearing load, reduced life and a negative influence on running behaviour and running accuracy.

Temperature management of the rotary axis in the form of targeted cooling and heating is generally necessary for high performance rotary axes.

Where there is non-uniform temperature distribution between the inner and outer ring, rotary axis bearings with ball contact (ZKLDF) show more tolerant behaviour than rotary axis bearings with line contact (such as axial/radial cylindrical roller bearings or crossed roller bearings).

The stated bearing characteristics only apply if the bearing preload remains unchanged. The bearing preload can be altered by mechanical stresses, such as those which can be caused by temperature differences or adjacent machin