NTV Scientific & Technical Firm is engaged in the restoration of not only worn-out screws, but also the restoration of barrels, honing of sleeves, boring, lining of domestic and imported cylinders with a diameter of 40 mm and length of up to 8,000 mm.

We offer a wide range of works on repair of barrels


Works on the inside diameter for the restoration of the barrel

  • Honing of sleeves - increase in diameter by 0.1 - 1 mm. This type of work is applicable when there is a nitrided layer on the working surface of the barrel (wear does not exceed 1 mm per diameter).

  • Cylinder boring - an increase in diameter by more than 1 mm. Barrel boring is advisable if honing of sleeves is not helping, when reaching the critical barrel wear in case there is no nitrided layer on the greater part of the working surface of the barrel. Boring when restoring a cylinder is carried out to not less than 2 mm (per diameter). After boring, it is recommended to carry out repeated chemical heat treatment (nitriding).

  • Nitriding is chemical heat treatment of parts to obtain a reinforcing layer on the working surface of the barrel with hardness of 700-900 HV and depth of nitrided layer of 0.30-0.50 mm.

  • Lining is the installation of nitrated liner with local wear of the barrel in the zone of entry, exit or in the area of the junction of its parts. Maximum length of the area to be lined is 500mm. Hardness of the working surface of the liner is 700-900 HV. Depth of the nitrated layer is 0.30-0.50 mm.

  • Replacement of parts of the barrel to be restored. If it is necessary to upgrade the equipment, it is possible to manufacture separate parts of the barrel (loading zone, splined liner, degassing zone) and connect them by installing flanges or an adapter coupling.

Works on the flanges

  • Flange manufacturing.

  • Repeated welding of flanges with elimination of the end and radial runout of the mating surfaces.

Works on the outside diameter of the cylinder

  • Restoration of fasteners – threads, collars, recesses, etc.

  • Changing the outside diameter of the cylinder by machining.


To determine the barrel restoration option, it is necessary to conduct diagnostics (defect identification).

Diagnostics of the barrel includes:

1) visual inspection to determine the nature of damage

2) measurement of the inside diameter of the barrel (up to 8,000mm) with an accuracy of up to 0.05 mm.

3) checking the barrel for straightness and squareness in relation to the mating surface of the mounting flange to the reducing gearbox (if necessary)

4) mapping of wear


Full diagnostics is needed to determine the actual condition of the system before the repair and, often, it saves the money of our Customers if it is revealed that there is no need for restoration operations.

Cylinder after Honing

Surface finish

You can find more detailed examples of executed works in the gallery of works

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