Causes and solutions of air bubbles on the surface of aluminum profiles

- Apr 11, 2019-

When the aluminum extruder is pressurized, there will be residual air in the aluminum profile, resulting in bubbles in the interior and surface of the aluminum profile, resulting in defects that cannot be completely solved, making the aluminum profile into waste. In order to avoid the air into the aluminum, it is important to find out the reason why the air was brought in. The following is the introduction of the four extrusion aluminum residual air inside the main factors.

The shear plane formed by the thermal shear of the rod is not perfect and vertical. Simple thermal shearing of long rods in industrial aluminum profiles will result in severe bending of the rods, resulting in an elliptical cross section of the aluminum profiles and a very large rounded corner at the end of the shearing. Even with the latest hot shears for long rods, the Angle of the edges of the sheared rods always produces an inverted circle, which is the best place for air residue.

Solution: to conduct standard inspection of aluminum bars, determined to eliminate unqualified aluminum bars.


The upset caused a residue of air. Only when the diameter of the cylinder holding the aluminum ingots is larger than the diameter of the rod can the rod be put into the cylinder holding the aluminum ingots. The gas must be vented when pressure is applied to the rod inside the aluminum cylinder causing the rod to expand to the diameter of the cylinder. The gas is not vented out and remains inside the aluminum ingot and eventually becomes a bubble.
Solution: according to the minimum size of the inner lining of the extrusion cylinder, configure the extrusion gasket, replace the extrusion cylinder regularly, check the corrosion and wash of the extrusion cylinder and the extrusion pad, measure the extrusion cylinder, and configure the appropriate extrusion gasket according to the inner and outer diameter of the extrusion pad; Clean the extrusion barrel once per shift with cleaning gasket, and etch and wash the extrusion barrel regularly.Air residue is caused by the connection of two aluminum rods. Because the surface of the two studs is essentially flat, the probability of carrying air in is very small. The sawing quality directly interferes with the amount of air carried between the two stubs. At present, there is a new high technology to prevent the two short rod contact, to eliminate the possibility of air entry.
Solution: determine the reasonable rod length of aluminum rod according to the process parameters such as the single weight of profile and the number of discharge.