Bımetallıc Barrel And Screw – Protectıon Agaınst Wear

Today’s plastics parts must meet the very specific needs, thus often requires some abrasive or corrosive additives (such as Glass fibre, CaCO3, Colours etc.) to achieve the specific characteristics. It is essential to take measures for continuous production. Former produces higher durability through hardened or Bimetallic Screws and Barrels as well as Nitrided ones.

Bimetallic Screws

Screws flight, exposed to wear, leads to reduced capacity and disruption of process conditions. In order to protect the screw flights and to postpone the wear, we apply abrasion and corrosion proof coating layer on the top of the screw flights. 

Bimetallic Screws Coating Alloys

Protection TypeBase of AlloyComponentsHardness R.T. (HRC)Wear ResistanceCorrosion Resistance
F 58FeC,Si,Mn,Cr,Mo,V,W56-60 HRc******
C 12CoC,Cr,W48-50 HRc*******
C 1CoC,Cr,W52-57 HRc********
N 56NiC,Si,Cr,B,Fe50-55 HRc********
N 57NiC,Si,Cr,B,Fe,W50-55 HRc*********
NW 83NiC,Si,Cr,B,Fe,W56-60 HRc**********

We offer proper corrosion or abrasion proof alloy depending on your process conditions and by this mean, screw life can be extended 2-5 times comparing to standard nitride screws.

Hard Surface Coatings

Hard surface coatings are applied using methods such as HVOF, PVD, PCD to increase screw surface strength, wear resistance, surface roughness, surface gloss and other surface properties.

Hard Surface Coating

Coating TypePlating ThicknessHardnessWear ResistanceCorrosion Resistance
Hard Chrome Plated200-300 µm800-1000 HV******
WC Plated250-300 µm900-1050 HV*********
TiN Plated3-4 µm2500 HV*******
CrN Plated3-4 µm3400 HV*****

Bimetallic Barrels

If the lifetime of the barrel is not long enough because of abrasive or corrosive additives or fillers, the right solution is bimetallic barrel. Thanks to special centrifugal casting technique for application of highly abrasion and corrosion proof alloys on the wear surfaces of the barrel. These alloys allows to run the barrel long time without changing it even with up to 50 % glass fiber including materials. Former will offer you proper base material for extrusion or injection molding with the suitable coating alloy for the efficient lifetime.

Bimetallic Barrel Protection Alloys

Protection TypeBase of AlloyComponentsHardness R.T. – (HRC)Wear ResistanceCorossion Resistance
F 121FeCr,Mo,Ni,B,C65-69 HRC******
N 115Ni-CoCr,Mo,Co*,B49-53 HRC******
N 216NiCr,Mo,Co,B,W*,C53-57 HRC*********

Materials And Abrasion Wear

Processing of glass fibre, calcite, reinforcing materials or similar additives, especially which cause high abrasive and corrosive wear, will shorten the life of the plasticizing unit. With the correct selection of screw and barrel material and the appropriate hardening method, your machine will continue to operate for longer periods of time by showing minimal irregularities.

Depending on the raw material and processing conditions, choosing the right design, steel and hardening method constitutes the basic 3 factors determining the life of the screw and barrel. Former Machine can guarantee optimum operating life by providing the most appropriate solution for your process. There are 3 types of wear on the barrel and screws. These are abrasive, corrosive and adhesive wear.

Abrasive wear; hard abrasive materials (glass fibre, glass containing materials, silica, calcite, talc, flame retardants) are due to long contact with each other in high temperature and pressure conditions.

Corrosive wear; It consists of the chemical interaction of any component in the formulation with the screw and creates pits in the form of tingling on the screw surface.

Adhezif wear is due to the contact of metal surfaces with each other. With the rotational movement of the screw, there is a continuous interaction between the screw pitch and the inner diameter of the barrel at high pressures. As a result, it will be observed that metal is stripping from the body of the screw or barrel.