Defect characteristics of surface cracks on aluminum profiles: The surface of aluminum profiles exhibits longitudinal, fish-like, repetitive, intermittent breaks, which are severely disconnected.

Causes of surface cracks in aluminum profiles:

(1) The extrusion coefficient of aluminum profile is too large, the extrusion temperature is too high (rod, barrel, die three temperature), and the extrusion speed is too fast;

(2) The squeezing force is unstable, suddenly high or low, or the speed difference between multiple speeds is obvious, and the speed change is sudden when shifting;

(3) When the aluminum alloy profile is extruded, the head end presses (presses) too fast, the tail end runs or does not decelerate, and a large amount of aluminum penetrates into the dead zone;

(4) The quality of the rod is poor, the rod is overburned, large grains, and loose. Pressure surplus (V3 aluminum) is too thin;

(5) The design and manufacturing of the extrusion mold with a severe flow velocity ratio is unreasonable.


Elimination of surface cracks on aluminum profiles:

(1) Profiles with excessive extrusion coefficients can be produced on a small machine with an appropriate extrusion ratio; in addition, the extrusion temperature must be controlled strictly according to the production process requirements and an appropriate extrusion speed must be used;

(2) The operator is concentrated, the speed is stable, the pressure cannot be high or low, and the manual operation is coordinated when changing gears;

(3) The front and rear ends of the aluminum profile stoppage are dead zones or V3 volume (aluminum rod surface) aluminum, which has many impurities, poor quality, and insufficient viscosity, so the extrusion speed of the head and tail of the profile should be slowed down;

(4) The surface of the aluminum rod should be fine and clean without oil stains, the internal organization must meet the standards, and the pressure surplus should remain normally (5% of the rod length);

(5) The designer of the extrusion die shall design and manufacture a qualified die with uniform flow velocity.