We offer extrusion, injection, and conveyance screws for a variety of applications servicing a multitude of polymer processing venues
Depending on the severity of the polymer flow environment, UNITED offers packages manufactured of the following base materials:
- 4340 HT carbon steel with hardened
alloy welded flight lands
- CPM 10v high chromium tool steel
- D-2 Tool Steel
- Stainless -300/400 series
We offer full cap flight encapsulation applied via a plasma transfer automated welding system, allowing the least amount of base material dilution into the hardened alloy. This results in highly wear-resistant flight lands and maximizes the life of the extruder screw.
Along with material and hard surfacing specification, UNITED offers custom screw profiles that maximize the performance of the processing feed screw. This is the most important feature of the screw. Over recent years, manufacturing technologies in the four and five axis arenas have allowed us to offer a variety of both distributive and dispersive mixing profiles. This allowance has afforded UNITED the ability to maximize production with both single and multiple polymer flows on the same extruder without screw change outs. Alloys and coatings offered are as follows:
Rebuilt Feed Screws
Almost all larger screws of 2.5" (65mm) diameter are available for rebuilding at the end of the initial screw life. The rebuild process follows along the same lines as a new screw, but allows for savings in both raw materials and limiting downtime. Generally, a 40% to 50% savings can be expected by rebuilding as opposed to purchasing new. The percentage savings raises with the larger diameter screws. UNITED exposes a screw to a pre-inspection involving a variety of non destructive metallurgy tests to deem the screw fit to be rebuilt and carry a new screw guarantee. It is important to maintain original equipment tolerance between screw and barrel to maximize performance and longevity of the components. At the time of screw rebuilding, barrels can be re-sleeved or honed oversize and the screw built to the correct clearance to insure product integrity.