Why does uneven cooling occur during the profile extrusion process?

There are five main causes of uneven cooling during the profile extrusion process:

(1) Uneven material discharge or significant wall thickness variations in the billet result in different amounts of material and heat distribution across various cross-sectional areas, requiring differing cooling capacities from different sections of the die, which easily leads to unbalanced cooling;

(2) Poorly designed cooling water channels cause inconsistent cooling rates across different parts of the profile—some sections cool faster while others cool more slowly within the sizing die;

(3) Due to the complexity of the profile cross-section, during vacuum adsorption and cooling in the sizing die, the outer surface of the visible side of the billet is cooled first, while internal ribs fail to receive synchronized cooling;

(4) Prolonged use of the sizing die can lead to varying degrees of scale buildup in the cooling water passages, reducing water flow and potentially causing partial blockages, thereby affecting the uniformity of cooling across different regions;

(5) Long-term failure to clean or incomplete cleaning of the vacuum air channels results in deposits blocking the vacuum orifices, significantly reducing suction force, preventing the profile from tightly adhering to the die, and consequently leading to insufficient or uneven heat exchange and cooling.