Plastic steel doors and windows are made of polychlorinated hexene (UPVC) resin as the main raw material, plus a certain proportion of stabilizer, colorant, filler, ultraviolet absorber, etc. through extrusion molding, and then made into door and window frames and fans by cutting, welding or screw connection. They are equipped with sealant strips, wool strips, hardware, etc. at the same time, in order to enhance the rigidity of profiles, Steel lining (stiffener) needs to be filled in the cavity of profile with more than a certain length. The door window made in this way is called plastic pvc sliding window.