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Aluminum profiles: Wall Thickness

Aluminum profiles: Wall Thickness

Extrusion is a plastic flow

Extrusion pressing is a plastic flow process in which the flow rate of the material through the outlet should be the same at all points of the cross-section of the extruded profile. The technological pressing window is determined by several factors, one of which is the profile wall thickness. Other factors that affect the pressing process include aluminum alloy, drawing ratio (the ratio of the cross-sectional area of ​​the profile to the transverse area of ​​the workpiece).

Factors for minimum wall thickness

Heat release

Heat generation is a key factor. Pushing aluminum through the matrix generates heat. The greater the degree of molding (the degree of deformation, the coefficient of drawing, etc.), the more heat is generated. High temperature creates problems for the quality of the profile surface in the form of scoring and cracks.

Tolerances

Tolerances highly depend on wall thickness. If the wall thickness is too small, it is very difficult to provide the necessary parameters of the metal flow and, therefore, small tolerances.

Alloy

The type of alloy greatly affects the minimum achievable wall thickness. Alloys with a high content of alloying elements are harder to compress than alloys with a low content of alloying elements and therefore require thicker walls.

Cross Section Complexity

In the general case, it is easier to obtain thin walls on simple profiles, compared to complex profiles. In hollow profiles with multiple channels, it can be very difficult to fill cavities between mandrels with metal. This, in turn, can cause increased tolerances on such walls.

Smaller profile - thinner than the wall

It is easier to get a thin wall on a small profile than on a large one.

Specific pressure

A press with high specific pressure (the ratio between the pressing force and the cross-sectional area of ​​the container) is usually more suitable for pressing profiles with thin walls.

The minimum wall thickness of 6xxx alloy profiles

The main parameters that control the minimum wall thickness when pressing aluminum profiles from 6xxx series alloys are the following:

Pressing force.

  • The maximum pressing speed at the exit of the die.
  • More complex matrix design and more complicated manufacturing.
  • Geometric tolerances for wall thickness.
  • Stability of geometric tolerances during the entire pressing process.

In addition to the technological limitations mentioned above, there is a very important economic aspect that must be taken into account. Most extruded aluminum profiles sell "by weight" and the production of thin-walled profiles may not be so profitable.

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