Aluminum alloys are widely used in radiator materials because of their light weight and beautiful appearance, good thermal conductivity and easy processing into complex shapes. There are three main types of aluminum alloy radiator materials: flat and wide, comb-shaped or fishbone-shaped; round or oval outer fins are radial and branch-shaped. Some of the radiator profiles are smaller in size and symmetrical in shape, which are easier to produce. Most of the radiator profiles are flat and wide in shape, with large external dimensions, and some are asymmetrical. Production is difficult. It is necessary to cooperate from ingot casting, die and extrusion process to successfully produce radiator profiles. At present, 6063 alloy is widely used because it has good mechanical properties in addition to good extrudability and thermal conductivity.

The production of aluminum alloy radiator profiles should start from the quality of the ingot, the material and design of the mold, the reduction of the extrusion force and the extrusion process.

Heat sink aluminum profile
1. Quality requirements of ingots

The surface of the ingot should be smooth, no segregation tumor or sticky sand and mud is allowed. The end face of the ingot should be flat, and it should not be cut into steps or the inclination is too large (the inclination should be within 3mm). Because of the stepped shape or too large a cut slope, when extruding the heat dissipation profile with a flat die, if there is no design guide, the ingot directly touches the die. Due to the uneven end face of the ingot, some places contact the die first, resulting in stress concentration. , It is easy to break the tooth shape of the mold, or cause the discharge sequence to be different, and it is easy to cause the phenomenon of mold blocking or poor extrusion molding.

2. Requirements for molds

Because the molds of the radiator profiles are many slender teeth, they have to withstand a large extrusion force, and each tooth must have high strength and toughness. To fracture those teeth with poor strength or toughness. Therefore, the quality of mold steel must be reliable, and it is best to use H13 steel produced by reliable manufacturers, or choose high-quality imported steel. The heat treatment of the mold is very important. It should be quenched by vacuum heating. It is best to use high-pressure pure nitrogen quenching to ensure that the performance of each part of the mold is uniform after quenching. After quenching, three times of tempering are required to ensure that the hardness of the mold has sufficient toughness under the premise of HRC48-52. This is an important condition to prevent the mold from breaking teeth.

3. Reduce the extrusion force

In order to prevent the broken teeth of the die, the extrusion force should be minimized, and the extrusion force is related to factors such as the length of the ingot, the deformation resistance of the alloy, the state of the ingot, and the degree of deformation. Therefore, the cast rod of the extruded heat-dissipating aluminum profile should not be too long, which is about (0.6 to 0.85 times the length of the normal cast rod). Especially when trying out the mold and extruding the first cast rod, in order to ensure the smooth production of qualified products, it is best to use a shorter cast rod, that is, a cast rod with a normal cast rod length (0.4 to 0.6) times. mold. For radiator profiles with complex shapes, in addition to shortening the length of the cast rod, pure aluminum short casting can also be considered for the first trial extrusion. After the trial extrusion is successful, the normal ingot is used for extrusion production.

4. Extrusion process

The key to the production of radiator profiles is the first trial of the extrusion die. If conditions permit, you can first do a simulation test on the computer to see if the working belt of the die design is reasonable, and then try the die on the extruder. The first mold test is very important. The operator should let the main plunger move forward and move slowly at a low pressure lower than 8MPa. It is best to have someone use a flashlight to look at the exit of the mold, and wait for every heat dissipation of the extrusion mold. After the sheets are uniformly extruded out of the die hole, the extrusion can be gradually accelerated and accelerated. When continuing to extrude after successful mold trial, attention should be paid to control the extrusion speed to achieve smooth operation. When producing radiator profiles, attention should be paid to the heating temperature of the mold, and the mold temperature should be close to the ingot temperature. If the temperature difference is too large, due to the slow extrusion speed when pressing, the metal temperature will drop, and the phenomenon of mold blocking or uneven flow rate is easy to occur.