Bimetallic cylinders and nitrided cylinders

If the screw is considered core, the cylinder must consequently be considered as the body of the plasticisation group. This component is of utmost importance since it must strengthen and secure the other group components.

Production of a Bimetallic Liner


The internal structure of a liner (bimetallic cylinder) is composed of various mineral types (see tables below) atomised and centrifuged by the process that you can see in the following video.

Video contribution submitted by Reiloy Gmbh

Processing and Inspection Phases


In the following video you can see the various and multifaceted phases of the production process (turning and milling) and a detail of an inspection of a plasticising cylinder.

Video contribution submitted by Reiloy Gmbh


Brixiaplast offers a range of bimetallic cylinders that cover various classes of use. Using the latest-generation centrifuge equipment, the powders are efficiently and homogeneously distributed and are thus free from distortions and porosity, reaching roughness parameters min. 0,15 μm, max. 0,8 µm.The durability life of our bimetallic cylinders varies 5 to 10 times more than that of other cylinders.

Iron Base – Chemical Composition (weight -%)

MaterialeDurezza HRC - (RT 300°C)Resistenza all’usura (abrasione)Resistenza alla corrosioneDil termica (25-400°C) - (1/MK)CrMoVNiBC
B1265-68 ( 55-57 )• • •12,81--42,13,6
B2165-69 ( 58-62 )• • •• • •14,2106-43,82

Suitability: (• good) to (• • • • excellent)

Nickel Base – Chemical Composition (weight -%)

MaterialeDurezza HRC - (RT 300°C)Resistenza all’usura (abrasione)Resistenza alla corrosioneDil termica (25-400°C) - (1/MK)CrMoVNiBC
B1552-56 ( 49-53 )• • • • •13,172353,8--
MASTER B2560-65 ( 53-57 )• • • • •• • • •11,541,5152401,9

Suitability: (• good) to (• • • • excellent)


Cylinder Dimensions

Cilindri bimetalliciMonovitebivite
DIAMETRO INTERNO15 - 400 mm35 - 180 mm
LUNGHEZZA9000 mm2500 mm
Cilindri bimetalliciMonovitebivite
DIAMETRO INTERNO14 - 300 mm35 - 180 mm
LUNGHEZZA9000 mm2500 mm


Cylinder Standard: This type of material is used for the transformation of polymers that do not cause abrasive and corrosive wear. Our continuing research into product improvement has us pushed over time into selecting the best steel available on the market. This material must be hardened with a nitriding thermal treatment.




Generally we use type NT5 72H vertically, which obtains a hardness of 950-1100 HV for a depth of 0,4 – 0,5 mm. It is possible to achieve various degrees of hardness and depth depending on the duration of treatment exposure. The vertical position of the components ensures uniform application with consequent homogeneity in the nitrided state.




We apply this treatment to the material when the needs arises to achieve a hard surface that is both homogeneous, neither too fragile nor able to loosen. This causes further material stability by eliminating internal tensions caused by cracks or fissures. The permeability of the treatment reaches up to 0,8 mm with hardness 1000 – 1050 HV.

A special CR-V-fused alloy is used for cylinders subjected to an elevated internal pressure.

Maximum permissible pressure inside the cylinder depends on the external D pressure for different diameters of hole B.



Brixiaplast offers solutions to improve screws and cylinders in the extrusion field to meet every need. In extrusion, the cylinder is typically lined internally in the supply zone in order to facilitate the loading of the material (or a supply socket is inserted).

In addition to classic nitrided standards, we also supply bimetallic cylinders with anti-wear screws with various special alloys depending on the application.The profile and correct geometry of the screws are designed and implemented taking into account the material and final product in a way to achieve maximum productivity.

The accrued experience of Brixiaplast centers on the production of parallel cylinders and screws that adapt better as a final product to the production of profiles and tubes. Thanks to the inter-meshing screw design, finished products have the following advantages:


    • Optimum material plasticisation


    • Improved mechanical quality of final product


    • Lower cost of additive resins


    • Perfect degassing of volatile elements


    • Excellent fuse homogeneity