Feedscrew & Barrel Engineers.

Phone: 01706 655402

Screw Refurbishment.

 

TWS has been refurbishing screws for over 30 years and can comfortably refurbish screws up to 450 mm Ø and 6100 mm in length.

 

Screws in most cases can be refurbished quite a number of times, we currently refurbish screws in either Stellite 6, 12, 1 and Colmonoy 56.

 

When refurbishing screws we can also renew or add an additional surface coating e.g

 

  • Nitriding
  • Hard Chrome plating
  • Tungsten Coating

 

 

 

 

 

 

 

 

 

 

 

Refurbishment Procedure

 

(General procedure for the refurbishment of a standard single flighted extruder screw)

 

Pack ready for dispatch.

 

Clean screw to remove all products.

Straighten screw prior to initial grind.

Grind screw on flight tips to remove all wear and damage, and establish a clean diameter (this provides the basic surface for rebuilding the screw flight).

Repair all screw damage (i.e. Damaged and chipped flights, root damage etc).

Weld buttering layer if required (the buttering layer is used to prevent the hard surface of the flight cracking due to different thermal expansion between the base material and the Hard facing weld).

Grind the buttering layer (to achieve a nominal thickness of Hard facing material on the crest of the flight).

Preheat the screw for welding.

Post heat the screw after welding and allow the screw to cool slowly.

Straighten screw prior to grinding.

Grind flight tips to final DIA plus 0.030".

Initial side grinding and polishing of screw.

Apply surface coating or treatment as required (i.e. Re-Nitriding etc).

Final grind of flight tips to give recommended radial clearance.

Final polish of completed screw.

Final inspection.

TWS 2016