(I): the extrusion coefficient of aluminum profile is too large, the extrusion temperature is too high (three temperatures of bar, barrel and die), and the extrusion speed is too fast.

(II): the extrusion pressure is unstable, high and low, or the speed difference between multi speed regulation is obvious, and the speed conversion is sudden fast when shifting.

(3): when extruding aluminum alloy profiles, the head end pressing (Stamping) is too fast, the tail end running speed or not slowing down, and a large amount of dead zone aluminum infiltrates.

(IV): the quality of the rod is poor, the rod is overburned, with large grains and loose. The residual pressure (V3 aluminum) is too thin.

(V): the design and manufacture of the extrusion die with the velocity ratio seriously misaligned is unreasonable.