Precision tubes for production of bearings

Precision tubes for production of bearings use the cold drawing process. Rolled seamless tubes are used as the semi-finished product.

Dimensions of the bearing tubes

OUTER DIAMETER (OD) 22,0 – 70,0 mm

WALL THICKNESS (WT) 3,0 – 8,0 mm

Steel grades for bearing tubes

DIN 17 230 100Cr6

Length of bearing tubes

length 3 000 mm with tolerance +/- 500 mm.

Testing of bearing tubes

Testing is done according to DIN 17 230.

Tolerances of tubes for bearing production

outside diameter D < 50 mm: 0 – +0.15 mm

outside diameter D > 50 mm: 0 – +0.25 mm

wall thickness: -/+ 7,5 % (after agreement 5 -/+ %)

Packaging of the fine-grained tubes

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

Tubes bound with a steel band.

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.

Demagnetizing

Residual magnetism 10 Oe maximum.

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.

Surface protection of bearing tubes

Surface of the tubes is oiled.

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.

Certificates

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

Straightness

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

Surface condition

Tubes are delivered with after its surface was soft annealed.

Maximum depth of defects is 0,25 mm and it includes decarbonizing.