Screws Construction and Regeneration

Screw manufacturing can be done following samples or drawings in various materials, with the possibility to make different profile based on the material that must be moulded.

Sintered steel screws complete our product range. These materials are chosen according to product characteristics to be processed, granting screw lifetime equal to 12 times of nitrided steel screws.

As soon as we receive the used screw we carry out the following checks

  • crest diameter
  • thread conditions
  • coupling conditions
  • kernel wear and coupling diameter

The scope of such verifications is to estimate the operations to carry out, in order to bring back the screw to the original level, operating on the wearied parts, ruined or broken off during the use. The restoration of the original diameter, essential condition to restore the capability to transport the plastic material to the original level, is done by means of welding material on the crest by means of automatic machines that assure a homogenous welding and absence of blows.
After that there is a finishing and final polishing, which assure a final rugosity lower then 0,06RA. There are several materials for repairing and the choice is based on customer requirements.


OverlayHardnessWear resistance (1-5)Corrosion resisteance (1-5)
Stellite Gr.150-55 HRC43
Stellite Gr.1245-48 HRC33
Castotig 558-62 HRC53
Base Nikel 5652-55 HRC45


Nitrided Standard – (41CrAlMo7) – 60 HRC
Characteristics: hardened and tempered steel, containing alloying elements such as aluminium, chromium Molybdenum, which during heat treatment (Nitriding), form particularly resistant nitrides, reaching hardnesses of around 1050 HV.
Suitable for: those who have no particular problems with wear and corrosion.

Hardened material – (X155CrMoV121) – 58-60 HRC
Characteristics: hardening steel with a high percentage of chromium, resulting in good toughness and high wear resistance.
Suitable for: those with significant wear problems.
Durability: 2-3 times the nitrided standard

Bimetal (wear and corrosion resistant) – 62-69 HRC
Properties: cylinders internally coated with a hard, approx. 5 mm thick, highly wear and corrosion resistant state reaching a hardness of approx. 65 HRC.
Suitable for: major wear and corrosion problems.
Durability: 4-5 times the nitrided standard