Rolling bearings — Linear motion
rolling bearings —
Part 2:
Static load ratings
ISO
14728-2
It is often impractical to establish the suitability of a linear motion rolling bearing selected for a specific application by testing. The following procedures have proved to be an appropriate and convenient substitute for testing:
— life calculation with dynamic load (ISO 14728-1);
— static load safety factor calculation with static load (ISO 14728-2).
Permanent deformation appears in rolling elements and raceways of rolling bearings under static loads of moderate magnitude and increases gradually with increasing load.
It is often impractical to establish whether the deformation appearing in a bearing in a specific
application is permissible by testing the bearing in that application. Other methods are therefore
required to establish the suitability of the bearing selected.
Experience shows that a total permanent deformation of 0,000 1 of the rolling element diameter, at the centre of the most heavily loaded rolling element/raceway contact, can be tolerated in most bearing applications without the subsequent bearing operation being impaired. The basic static load rating is, therefore, given a magnitude such that approximately that degree of deformation occurs when the static equivalent load is equal to the load rating.
Tests in different countries indicate that a load of the magnitude in question may be considered to
correspond to a calculated contact stress of
— 5 300 MPa for recirculating linear ball bearings, sleeve type,
— 4 200 MPa to 4 600 MPa for recirculating linear ball bearings, linear guideway type
— 4 200 MPa to 4 600 MPa for non-recirculating linear ball bearings, and
— 4 000 MPa for linear roller bearings,
at the centre of the most heavily loaded rolling element/raceway contact. The formulae and factors forthe calculation of the basic static load ratings are based on these contact stresses.
The permissible static equivalent load may be smaller than, equal to or greater than the basic static
load rating, depending on the requirements for smoothness of operation and friction, as well as on
actual contact surface geometry. Bearing users without previous experience of these conditions should consult the bearing manufacturers.
rolling bearings —
Part 2:
Static load ratings
ISO
14728-2
It is often impractical to establish the suitability of a linear motion rolling bearing selected for a specific application by testing. The following procedures have proved to be an appropriate and convenient substitute for testing:
— life calculation with dynamic load (ISO 14728-1);
— static load safety factor calculation with static load (ISO 14728-2).
Permanent deformation appears in rolling elements and raceways of rolling bearings under static loads of moderate magnitude and increases gradually with increasing load.
It is often impractical to establish whether the deformation appearing in a bearing in a specific
application is permissible by testing the bearing in that application. Other methods are therefore
required to establish the suitability of the bearing selected.
Experience shows that a total permanent deformation of 0,000 1 of the rolling element diameter, at the centre of the most heavily loaded rolling element/raceway contact, can be tolerated in most bearing applications without the subsequent bearing operation being impaired. The basic static load rating is, therefore, given a magnitude such that approximately that degree of deformation occurs when the static equivalent load is equal to the load rating.
Tests in different countries indicate that a load of the magnitude in question may be considered to
correspond to a calculated contact stress of
— 5 300 MPa for recirculating linear ball bearings, sleeve type,
— 4 200 MPa to 4 600 MPa for recirculating linear ball bearings, linear guideway type
— 4 200 MPa to 4 600 MPa for non-recirculating linear ball bearings, and
— 4 000 MPa for linear roller bearings,
at the centre of the most heavily loaded rolling element/raceway contact. The formulae and factors forthe calculation of the basic static load ratings are based on these contact stresses.
The permissible static equivalent load may be smaller than, equal to or greater than the basic static
load rating, depending on the requirements for smoothness of operation and friction, as well as on
actual contact surface geometry. Bearing users without previous experience of these conditions should consult the bearing manufacturers.
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