Here is the general installation method for the conical twin screws of a plastic extruder:
1. Preparation Work
Clean relevant components of the extruder, including the barrel, screws, coupling, etc., to ensure there is no debris or dirt.
Check whether the new screws meet the specifications and whether there is any damage or deformation.
Prepare required tools, such as wrenches, screwdrivers, micrometers, etc.
Ensure the extruder’s frame is level with the ground, and adjust it if necessary.
Release all heaters on the screw barrel and connectors.
2. Installing the Screws
Insert the two screws symmetrically into the barrel, first pushing the screws tightly toward the small end of the barrel. Observe the position of the screws; typically, the screw heads should be flush with the barrel, or may be 1-2mm longer or shorter than the barrel.
Push the tails of the screws tightly backward toward the gearbox side and measure the backward distance (assume this distance is 22mm). Determine the thickness of the screw plug based on the relative position of the screws and the barrel in the first step:
If the screws are flush with the barrel in the first step, the screw plug thickness should be 17mm (22mm – 5mm).
If the screws are 1mm longer than the barrel, the screw plug thickness should be 18mm (22mm + 1mm – 5mm).
If the screws are 1mm shorter than the barrel, the screw plug thickness should be 16mm (22mm – 1mm – 5mm).
Generally, set the screw plug thickness to 17mm first, then adjust it according to actual conditions.
Tighten the screw plug into the screw shaft, then install the large nut onto the barrel. Reconfirm the screw position to check whether it has retracted by 5mm (4-6mm is acceptable).
Observe the gap between the two screws from the feed inlet to ensure it is uniform.
3. Final Inspection
Before starting the machine, reconfirm that the screws have retracted toward the gearbox side. Otherwise, when the machine starts, the screws will move forward to the small end of the barrel, which may cause issues such as immobility.
Do not operate the extruder without feeding material, as this may cause the screws to move forward and get stuck.
