Precision tubes for production of bearings

Standards and steel grades,
Tube sizes

Precision tubes for production of bearings use the cold drawing process. Rolled seamless tubes are used as the semi-finished product. Overview of dimensional standards and technical-delivery conditions of the tubes for hydraulic and pneumatic circles are presented in a separate overview .

Dimensions of the bearing tubes

Outside diameter ranges from 22 to 70 mm and the wall thickness from 3.0 to 8.0 mm. Precision steel tubes for production of bearings are delivered according to the customers’ specification. More detailed overview of produced dimensions is presented in the table.

The Steel grades for bearing tubes

Bearing tubes are produced from the following steel. According to DIN 17 230, 100Cr6 possibly grade 14 109 (STN). Chemical composition of the steel and its mechanical properties are presented in a separate overview. Upon agreement it is possible to deliver other types of steel.

Delivery condition and thermal treatment of precision tubes for bearing production

Bearing tubes are delivered are delivered in the GKZ + K +G condition, i.e. annealed to globular carbides – cold drawn – soft annealed. Overview of other thermal treatment conditions may be found here.

Length of bearing tubes

length 3 000 mm with tolerance +/- 500 mm

Tolerances of tubes for bearing production

outside diameter	D < 50 mm	0 +0.15 mm
outside diameter	D > 50 mm	0 +0.25
wall thickness	-/+ 7,5 % (after agreement 5 -/+ %) of the wall thickness

 

 

Straightness of precision tubes for bearing production

1 mm / m (1 : 1 000) measured on the outside surface, maximum 2.5 mm / 3000 mm.

Ends of the bearing tubes

Tubes have its ends smooth, plain square cut ends, one beveled 0.5 to 4 00 x 45°.

Testing of bearing tubes

Testing is done according to DIN 17 230.

Marking of bearing tubes

Bundles of tubes are marked with label.

Surface protection of bearing tubes

Surface of the tubes is oiled.

Packaging of the fine-grained tubes

Tubes are packed in circular weighing between 1 000 – 3 000 kg.

Certificates for bearing tubes

According to DIN 50049 - EN 10204 - 3.1.B.

Steel hardness for bearing tubes

After the soft annealing the hardness ranges is 174 – 220 HB. Hardness value dispersion along the length of the tube is 15 HB maximum. Minimum hardness according to the hardness test is 61 HRc.

Surface condition of bearing tubes

Tubes are delivered with after its surface was soft annealed. Maximum depth of defects is 0,25 mm and it includes decarbonizing.

Microstructure of bearing tubes

Testing procedures according to SEP 1520: carbide sizes 2.1 – 2.3, lamellar pearlite 3.0, carbide net 5.2, carbide line spacing (max 6.3 – continuous, max 7.3 – released).

Micropurity

Tested according to DIN 50602. Total value of oxide and sulphur micropurity K3 <= 10.

Demagnetizing

Residual magnetism 10 Oe maximum.

Notes:
The tubes also may be delivered as hot rolled. It is also possible to deliver bearing tubes according to STN EN ISO 683-17. It is annealed and automated steel that it is destined for hot treatment, part 17: steel for roller bearings.