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Product Range
With a unique combination of Assel Mills and a PQF mill, ISMT is one of the world largest and most diversified manufacturers of specialized seamless tubes. We produce both Hot-finished as well as Cold-finished seamless tubes ranging from an outside diameter of 6mm to 273mm. Our tubes are used in a variety of applications such as the manufacture of auto-components, bearing races, OCTG products, drill rods, boilers, heat-exchangers, etc.

Apart from tubes, ISMT manufactures a variety of value added products such as cold rolled and machined rings for bearings and constant velocity (CV) joints, swaged and machined axles for trucks, steering columns for two-wheelers and ready-to-hone tubes for hydraulic cylinders.
Hot Finished Seamless Tubes Cold Finished Seamless Tubes
Value Added Products
Starter gears for automobiles Spindle axles for automobiles Cages for constant velocity joints
Starter gears for automobiles Spindle axles for automobiles Cages for constant velocity joints
Multi-track sleeves for linear bearings Shaped tubes OCTG Couplings
Multi-track sleeves for linear bearings Shaped tubes OCTG Couplings
Inner races for bearings
Inner races for bearings
TubesAt ISMT we have invested in sophisticated facilities and developed specialized processes for the manufacture of bearing tubes. Apart from producing tubes from standard bearing grade steels such as SAE 52100 and DIN 100 Cr6, the company also produces tubes from tailor made steels.

The steel used for the manufacture of bearing tubes is produced exclusively through the electric arc furnace route, is ladle refined and is vacuum degassed. As a result, the steel is extremely clean ensuring a high fatigue life for the bearing.

ISMT supplies bearing tubes to the major bearing manufacturers throughout the world.

Tube Tolerances

Oxygen Content
Oxygen content < 15ppm. On specific request oxygen content < 10 ppm can be offered.

Inclusion Rating
The tubes are tested to ensure that the steel is free from injurious imperfections such as piping, cracks, porosity, segregation or injurious inclusions as referred to in ASTM-381. The inclusion rating is evaluated in accordance with Plate III of ASTM E-45 ensuring that the length of any inclusion does not exceed 0.65 mm and that the worst field of each inclusion type from each specimen does not exceed the limits given below.

Inclusion Rating Worst Field
A B C D Type
2.0 1.5 - 0.5 Thick
1.5 0.5 - 0.5 Thin

Heat Treatment / Microstructure
The tubes are spheroidized and annealed to ensure that the microstructure consists of spheroidized commentate in a ferrite matrix with carbide size conforming to Plates 2 to 4 as per IS 4398-1972 and CG 2.1 - 2.3 as per SEP 1520-78. We ensure that there is no carbide network and the structure is free from segregation of carbides in either streak or cluster form.

Condition Brinell Hardness
Hot finished, spheroidized 230 BHN max.
Hot finish, spheroidzed & peeled 230 BHN max.
Hot finished, spheroidized & stress relieved 207 BHN max.
Spheroidized, cold pilgered / roto-rolled 250-320 BHN

Decarburisation Depth
Hot finished: 0.50 mm max. per side
Cold finished: 0.20 mm max. per side

Dimensional Tolerances**
Description Size Range Tolerance
OD (mm) OD (mm) Wall t (%)
Hot rolled 38 - 75
>   75 - 100
> 100 - 125
> 125 - 200
+/- 0.4
+/- 0.5
+/- 0.6
+/- 1.0%
+/- 5%
+/- 5%
+/- 5%
+/- 10%
Hot rolled and Peeled >   36 - 120 +/- 0.40
    - 0.00
+/- 5%
+/- 5%
+/- 5%
+/- 10%
Cold pilgered / Roto rolled
  19 - 80
> 80 - 91
+ 0.30
- 0.00

+ 0.40
- 0.00
+/- 5%

+/- 5%
**Note: Tighter tolerances can be offered on specific request.

Eccentricity     Straightness
Hot finished & peeled 10% of wall thickness   Cold pilgered / roto-rolled 1 : 1000
All other tubes OD < 125mm: 5% of wall thickness
OD > 125mm: 10% of wall thickness
  Hot finished / hot finished & peeled 1 : 600
Tubes are generally supplied in random lengths of 3 - 4.5 mts with 10% up to 2mts.

End Preparation
Square cut & one end chamfered.

Size Range
Hot Finished Bearing Cold Pilgered Bearing
ISMT Limited is one of the few companies in the world to offer just-in-time delivery of hardened ring sets for the manufacture of bearing races, bearing bushes and sleeves for linear bearings. These rings are manufactured through a process of cold ring rolling (on Bad Deuben machines) and / or machining.

  • » Inner and outer races (with or without sealing groove for ball bearings)
  • » Angular contact ball bearings
  • » Needle roller bearings
  • » Cylindrical / spherical roller bearings
  • » Self aligning bearings
Bearing - Rings
Bearing - Rings Bearing - Rings Bearing - Rings
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