In the extrusion production process of heat sink aluminum profiles, common defects include bending, twisting, deformation, slag inclusion, etc. The defects of "adsorption particles" are difficult to detect without careful observation or contact. The harm is that it is difficult to remove in the production process of electrophoretic and spray coating profiles, which affects the surface beauty of the profiles and causes waste. The main reasons for the formation of "adsorption particles" are as follows:
1、 The influence of casting rod quality
The quality of the casting rod is an important factor affecting the surface and extrusion forming of the heat sink aluminum profile. The formation of "adsorbed particles" is closely related to the quality of the casting rod. The common structural defects of cast bars include slag inclusion, looseness, coarse grain size, segregation, bright grain, etc. All of these cast bar defects have one thing in common, which is poor welding with the cast bar matrix, resulting in discontinuous flow of the matrix, which is an important factor in the formation of "adsorption particles".
2、 Influence of mould
In extrusion production, the mold works under high temperature and high pressure, resulting in elastic deformation. The working belt of the mold starts to be parallel to the extrusion direction. After being subjected to pressure, the working belt deforms into a trumpet shape, and only the cutting edge of the working belt contacts the aluminum profile of the heat sink, forming a sticky aluminum, similar to the chip tumor of a turning tool. During the formation process of adhesive aluminum, particles are continuously carried out by the heat sink aluminum profile and adhere to the surface of the profile, resulting in "adsorbed particles".
3、 The influence of extrusion process
The correct selection of extrusion process parameters is also an important factor affecting the adsorption of particles. If the extrusion temperature is too high and the extrusion speed is too fast, the more "adsorbed particles" there will be. The reason is that due to high temperature and fast speed, the flow speed of the profile increases, the degree of mold deformation increases, the flow of metal accelerates, and the deformation resistance of the metal is relatively weakened, making it easier to form aluminum adhesion.
The main influencing factors of "adsorption particles" are casting rods, molds, and extrusion processes, and the operational level of operators is also reflected in these three elements. Based on production practice, continuous analysis of problems and summarization of experience can reduce or avoid "adsorption particles", greatly improving the yield and production efficiency of heat sink aluminum profiles.
