It is not uncommon for the screen of a screw press to wear out. Abrasion from dry manure is a cause. Also, operating with a worn screw puts increased loading on the machine. This can cause the screw to shift sideways, leading to rubbing between the screw and the screen.
When a screw is tight against a screen, the screen material bows outward, minimizing wear. Consequently wear tends to occur where there are reenforcing rings on the screen that prevent it from bowing away from the screw.
Screen Patch Kits are available for all the Series KP presses. The patches supplied by Vincent are made of 11 gauge steel (1/8" thick) with 3/8" hole perforations. This assures plenty of draining surface even when extensive patching is required.
The patches can be welded in place without having to remove a screen from a press.
The kits can be used only if the screen is still relatively intact. If it has been torn into two or more pieces or if it has been beer-canned, it is likely beyond repair.
The kits consist of a series of pairs of half-cylinder sleeves that fit around the outside of the screen. Each sleeve is about 180º so that the two pieces of a pair can be wrapped around a worn or torn part of a screen.
Once the sleeves are in position they should be TIG welded in place. (Stick welding can be made to work.) The width of the patch sleeves is such that they fit between two adjacent reinforcing rings of the original screen. The patches are welded to these rings and to each other.
The patches, like the original screens, are made of stainless steel.
In a bind, patches can be made of any sheet metal. Because of the excess of open area in the original screens, patches need not be made of perforated material.