Correct selection method of aluminum alloy extrusion speed

Extrusion speed refers to the outflow speed of the product or the speed at which the main plug of the extruder moves forward. In actual production, the outflow speed of the product is controlled by adjusting the forward speed of the main plunger. Extrusion speed is an important factor affecting production efficiency and also affects product quality (such as product surface and size, etc.), so an appropriate extrusion speed is crucial.
The extrusion speed of 6063 aluminum alloy profiles (die outflow speed) ranges from 9 to 60m/min, among which the solid parts are 9 to 20m/min.

Huawei aluminum alloy

The extrusion speed is related to factors such as alloy type, ingot state and size, product shape, degree of deformation (or extrusion coefficient), deformation temperature, tool (mold) structure, and process conditions.

1.1: Influence of ingot quality
The quality indicators of ingots are mainly grade one grain size, less hydrogen content (below 0.1.mL/100g aluminum), less and fine slag particles (remove slag particles above 0.008mm), uniform metallographic structure, no cracks, looseness, and pores and elemental segregation. In this way, the plasticity and deformation of the ingot are good, the extrusion force of the aluminum profile is reduced, and the extrusion speed is increased. Otherwise, the extrusion speed will be slow and the die loss will be large.

1.2: Influence of extrusion temperature
When metal is extruded, as the temperature rises, the non-uniformity of metal fluidity will increase. During the entire extrusion process, the temperature of the ingot in the deformation zone also gradually increases, and the faster the extrusion speed, the higher the temperature, and the temperature rise can reach about 100C. When the metal temperature in the deformation zone exceeds the maximum allowable critical deformation temperature, the metal will enter a hot and brittle state and form extrusion cracks. Therefore, when the ingot temperature is high, the extrusion speed must be gradually reduced during the extrusion process. The 6063 aluminum alloy ingot is generally preheated to 480~520C, and the extrusion barrel is preheated to 400~450C.

1.3: profile shape
The impact of size and shape The external dimensions and geometry of the concave profile have a significant effect on the metal outflow velocity of the extruded product. The general rule is: the geometric shape of the product is simple, the symmetry is good, and the product with a small width-to-thickness ratio can be relatively higher; on the contrary, the extrusion speed of the product with complex geometric dimensions, large width-to-thickness ratio, large wall thickness difference, and poor symmetry should be relatively slow. Some. Under the same conditions, the thinner the wall thickness of the product, the more uniform the deformation of the product along the cross-section, the smaller the tendency to produce extrusion cracks. Therefore, the extrusion speed can be faster.

1.4: Influence of deformation degree
The greater the degree of deformation of the product, the greater the extrusion force required, and the greater the heat of metal deformation, so the outflow speed of the product is slower; on the contrary, the degree of deformation is small and the metal flow is uniform, and the extrusion speed can be faster.

1.5: Influence of mold structure
When extruding aluminum alloy profiles, which type of core to use is determined by the characteristics of the profile. Generally, the solid profile adopts a flat die, and the hollow profile adopts a tongue type or a split combination die. For 6063 alloy, the flat die has less resistance than the tongue die or the split split die, so the extrusion speed can be higher. For the mold core with the same structure, the wider the working belt of the mold core, the greater the friction between the alloy and the working belt surface, the greater the additional tensile stress on the surface of the product, and the higher the tendency of extrusion cracks on the surface of the product. Therefore, the extrusion speed need to be reduced accordingly. Secondly, from the perspective of the surface friction between the metal and the core working belt, the harder and smoother the core working belt, the faster the extrusion speed should be.