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Reasons for the formation of “adsorbed particles” on the surface of extruded aluminum profiles

Posted by: Alloy 2021-07-15 Comments Off on Reasons for the formation of “adsorbed particles” on the surface of extruded aluminum profiles

In the extrusion production of aluminum profiles, common defects are relatively intuitive, such as bending, twisting, deformation, and slag inclusion. The defect of “adsorbed particles” is difficult to find without careful observation or touching by hand. The hazard is: in the production process of electrophoresis and spraying profiles, it is difficult to remove them, which affects the appearance of the profiles and causes waste products.

The main reasons for the formation of “adsorbed particles” are as follows:

1 Influence of mold

In extrusion production, the mold is working under high temperature and high pressure, which will produce elastic deformation. The working belt of the mold starts to be parallel to the extrusion direction. After being pressed, the working belt deforms into a horn shape. Only the cutting edge of the working belt touches the sticky aluminum formed by the profile, which is similar to the cutting edge of a turning tool. During the formation process of sticky aluminum, particles are continuously carried out by the profile and adhere to the surface of the profile, resulting in “adsorbed particles”.

2 The influence of extrusion process

The correct selection of extrusion process parameters is also an important factor affecting the “adsorbed particles”. If the extrusion temperature is too high and the extrusion speed is too fast, the more “adsorbed particles” will be. The reason is that due to the high temperature and high speed, the flow speed of the profile increases, the degree of mold deformation increases, the flow of metal is accelerated, and the resistance to deformation of the metal is relatively high. Weakened, the phenomenon of aluminum sticking is more likely to form.

3 The influence of casting rod quality

The quality of cast rods is an important factor affecting the surface and extrusion of aluminum profiles. The cause of “adsorbed particles” has a lot to do with the quality of the cast rod. The common structural defects of cast rods include slag inclusion, porosity, coarse grains, segregation, bright grains, etc. All these casting rod defects have one thing in common, that is, they are not well welded to the base of the cast rod, causing the flow of the base to be inconsistent. Continuity, which is an important factor in the formation of “adsorbed particles”.

The influencing factors of “adsorbed particles” are mainly three aspects: mold, casting rod, and extrusion process. The operating level of the operator is also reflected in these three elements. On the basis of production practice, the problems are continuously analyzed and the experience is summarized. It can reduce or avoid “adsorption particles”, greatly improving the yield and production efficiency of the profile.

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