Extrusion Technology of Aluminium profiles for LED heatsink

by / Wednesday, 21 March 2018 / Published in Company Blog

Aluminum alloys are widely used in LED heatsink because of their light weight, good

appearance, good thermal conductivity and easy processing into complex shapes. There are mainly three types of aluminum alloy heatsinks: flat-width, comb-shaped, or fish-bone-shaped, and round or oval-shaped outer radiating fins are radial pattern. Their common characteristics are: the short distance between the fins, the formation of a groove between the adjacent two fins, the deep width ratio is large; wall thickness difference is large, the general fins thin, and the thickness of the base plate is large. Therefore, it is very difficult to design, manufacture and produce molds for heat-dissipation profiles.

 

LED heatsink profiles have a relatively small size and symmetrical shape. Products are relatively easy to produce. Most of the heatsink profiles are flat, wide, and have a large size, some are asymmetrical, and the depth-to-width ratio between the fins is large. It is difficult to produce. Need to cooperate with the ingot, mold, extrusion process in order to successfully produce heatsink profiles. The alloy used to extrude the heatsink profile must have good extrudability and thermal conductivity, and alloys such as 1A30, 1035, and 6063 are commonly used. More commonly used is 6063 alloy, because it has good mechanical properties, in addition to good extrudability and thermal conductivity.

 

The production of aluminum alloy heatsink profiles starts with the quality of the ingot, the material and design of the mold, the reduction of extrusion force, and the extrusion process.

 

Quality requirements of ingot

The surface of the ingot should be smooth and no segregation or sticking of sand. The end surface of the ingot should be flat and cannot be cut into steps or cut too much (cutting angle should be within 3mm). Because the steps or slants are too big, when the heat dissipation profile is extruded by the planar die, if there’s no designed diversion, the ingot will directly hit the mold. Because the end surface of the ingot is uneven, some places first contact the mold and cause stress concentration. , It is easy to squeeze the tooth profile of the mold, or cause the material to be discharged one after another, and it is easy to bring a phenomena of blocking or poor extrusion.

 

The mold requirements

Because the heatsink profile mold is a lot of slender teeth, to withstand a lot of pressure, each tooth should have high strength and toughness, if the performance of each other is very different, it is easy to those teeth that have poor strength or toughness break. The key to successful extrusion of heatsink profiles is the design of the mold and the precision of manufacture. Generally try to avoid direct extrusion of the ingot to the mold working belt. For the relatively mature design of the section, the use of embedded alloy steel mold is also a better method, because the alloy steel mold has better rigidity and wear resistance, is not easy to produce deformation, is conducive to the formation of the heatsink profile.

 

Reduce the squeeze force

In order to prevent the broken teeth of the mold, the extrusion force should be reduced as much as possible, and the extrusion force is related to the length of the ingot, the resistance of the alloy deformation, the state of the ingot, and the degree of deformation. For a heatsink profile with a complex shape, in addition to shortening the length of the cast rod, it is also considered to use pure aluminum short casting as the first trial extrusion, and after the trial squeezing is successful, the normal ingot casting is used for extrusion production. As to the effect of the deformation degree, since the sectional area of ​​the radiator profile is generally relatively large, the extrusion coefficient is generally within 40, so its influence is small.

 

Extrusion process

The key to the production of heatsink profiles is the first test die of the extrusion mold. If conditions permit, you can do a simulation test of the computer first to see if the work zone of the mold design is reasonable, and then try the mold on the extruder. The first tryout is very important. When the test is successful, the extrusion speed should be controlled to achieve a smooth operation. When producing heatsink profiles, the heating temperature of the mold should be taken into consideration. The temperature of the mold should be similar to the temperature of the ingot. If the temperature difference is too large, due to the slow extrusion speed when the pressure is applied, the temperature of the metal will drop, and the phenomenon of blockage or uneven flow rate will easily occur.

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