Causes and Solutions of Bubbles Appearing on the Surface of Aluminium Extruded Profiles

When the aluminium extruded profile is pressurized, air will remain in the aluminium profile, causing air bubbles to appear inside and on the surface of the aluminium profile, resulting in defects that cannot be completely resolved, making the aluminium profile waste. In order to avoid air entering the aluminium profile, be sure to find out why the air is being brought in. Introduced below are the main factors of air trapped inside the four aluminium extruded profiles.


Ⅰ. Air residue due to hot shearing of long bars of aluminium extruded profiles


The shear plane formed when the rod is thermally sheared is absolutely not perfect and vertical. The simple thermal shearing of long rods in industrial aluminium profiles will cause the bending of the column rods to be very serious, resulting in an oval cross-section of the aluminium profile and a huge rounded corner being cut. Even with the latest hot rod shears, the edge angles of the rods being cut are always rounded, and these rounds are the best places for air to stay.


Solution: Carry out standard inspection on aluminium rods, and resolutely eliminate unqualified aluminium rods.


Ⅱ. The upsetting of aluminium extruded profiles leads to the residue of air


Only when the diameter of the cylinder containing the aluminium ingot is larger than the diameter of the rod, the rod can be put into the cylinder containing the aluminium ingot. After the pressure is applied to the rod inside the aluminium ingot cylinder, the rod must expand to the diameter of the cylinder, and the entrained gas must be discharged. The gas is not discharged, and it will eventually become bubbles in the aluminium ingot.


Solution: configure the extrusion gasket according to the minimum size of the inner lining of the extrusion cylinder, replace the extrusion cylinder regularly, check the erosion and washing of the extrusion cylinder and the extrusion pad, measure the inner and outer diameters of the extrusion cylinder and the extrusion pad configure the appropriate extrusion gasket according to the size, use the cleaning gasket to clean the extrusion cylinder once per shift, and etch and wash the extrusion cylinder regularly .


Ⅲ. The connection of two aluminium rods of aluminium extruded profiles leads to the residue of air


Due to the contact of the two aluminium rods, air will remain. Because the surface layers of the two stub rods are basically flat, the probability of entraining air is very small. The quality of the sawing directly interferes with the amount of air carried between the two stubs. At present, there is a high-tech that can prevent the two short column rods from being connected to eliminate the possibility of air entering.


Solution: Determine the aluminium rod with a reasonable rod length according to the process parameters, such as the single weight of the aluminium extruded profiles and the number of discharge counts.


Ⅳ. Aluminium extruded profiles lead to air residue


When extruding aluminium profiles, it is necessary to avoid the entry of air, so as to avoid air residue, which will cause various defects in post-processing.


1. Improper oiling will cause product bubbles.


Solution: Use the correct oiling method and reduce the amount of oiling; strengthen the training of employees' operating skills before they work.


2. The excess pressure is too thin, causing the metal of the shunt hole to be pulled out during shearing, leaving a gap in the shunt hole of the mold.


Solution: Reserve reasonable excess thickness according to the tonnage of the extruder, and the aluminium rod with a reasonable rod length is determined according to the process parameters, such as the single weight of the profile and the number of discharge counts.


3. The extrusion die is designed with a flat die welding chamber, and the shunt hole of the shunt die is too large to cause air bubbles to flow into the cavity.


Solution: Reduce the size of the flat die welding chamber, reduce the die hole of the split die, and keep the distance from one side of the extrusion cylinder more than 5MM.


4. Extrusion die design case


For example, in the mold design of the motor shell, the product often has bubbles and other phenomena due to the mold in the production process of the aluminium extruded profiles of the motor shell. At the same time, the life of the mold is not long, and the mold fails prematurely. After the die fails, the interchangeability of the motor housing is poor.

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0086-755-29991176