Refurbishment and Repairs – Screws
Repairs
We can carry out minor repairs to damaged screw flights which may have been caused by a foreign part passing through the feed opening and into the screw channels. The damaged area is prepared for rebuilding with weld and final grinding to the original flight profile. We aim to complete minor repairs through our fast track production planning where standard turn round for flight repairs is 24 Hours, delivered to us before 16:00 hrs collection or despatched the following day by 15:00 hrs. (Standard working week).
In certain situations for minor flight repairs, we can carry out onsite repairs. Working to a clearly defined field service procedure our trained and experienced welding technicians will attend to minor repairs at your location.
Refurbished Screws
Most screws are suitable for a number of refurbishments before the thermal stresses imparted by re-welding could result in weakening the structure of the base metal and lead to subsequent fracture.
Refurbishment can be a cost effective option compared to purchasing new, and by bring the component to a serviceable standard and re-establishing the correct clearance between screw flight tip and barrel wall, the refurbished screw will provide extended service life with processing and production levels similar to the standard of a new component.
Screws can normally be refurbished to standard diameter through local weld repair or surface treatment and rebuilding of the flight profile. Before any refurbishment is undertaken a thorough inspection is made of the screw to determine the extent of wear, corrosion or other damage and to establish the scope of work necessary to bring the screw to serviceable standard. If there is excessive wear or corrosion on the root diameter or flight it may not be possible to make a repair, it is therefore important to monitor the wear rate of the screw and barrel to ensure both long term processing efficiency and that corrective action, either replacement or refurbishment, is planned with minimum disruption to your production. MAGOG offer a condition monitoring service to help identify any potential issues and predictive planning for replacement or refurbishment.
 | 1. Worn and damaged screw |
2. Magog refurbishing |  |
 | 3. Magog finished product |
Rebuilding of the screw flights follows a standard process: first preparation grinding the screw(s) to achieve a uniform outside diameter across the flights, which are then re-built using a special grade High Speed Toolsteel that is applied by means of a TIG welding process. What makes the Magog system unique is that we have developed a process whereby we are able to integrate the hardfacing with the parent steel of the screw. This gives optimum cohesion of the materials and significantly reduces the risk of cracking and delamination of the hardfacing. Furthermore, when the refurbishment of the screw is completed, there is a minimum of 1.5mm on diameter of hardfacing on the flights. Final grinding of the flights ensures the correct diameter and parallelism of the finished part.
Where screws are refurbished in conjunction with the refurbishment of barrel, and the barrel bore is honed to parallel and concentric, the screw diameter will be finished to achieve the original design standard clearances.
