Precision extrusion tolerances for aluminum profiles

The minimum wall thickness of the profile is only 0.4 mm, and the tolerance requirement is ±0.04mm. The extrusion production process is quite strict for equipment, molds and processes. This extrusion technique is often referred to as precision extrusion.

1. Precision extrusion technology requirements

Generally speaking, aluminum alloy thermal extrusion deformation degree, extrusion temperature and speed changes, extrusion equipment on neutral, mold deformation, etc. are easy to affect the accuracy of profile size, and their mutual influence factors are difficult to overcome. Figure 3 shows the factors that influence precision extrusion.

2. Requirements for the mold

Mold is the most direct factor affecting the size accuracy of extruded products, to ensure that extrusion products in the production interruption surface size unchanged or little change, mold rigidity, heat resistance, wear resistance to meet certain requirements.

First of all, to ensure that the mold is not easy to deform at high temperature and high pressure, has a high heat resistance, more stringent for precision extrusion, the requirements in the operating temperature (around 500 degrees C), mold material yield strength is not less than 1200N/mm2. In the nitride layer hardness and thickness, the hardness of the nitride layer is generally required to be above 1150HV, the depth of the nitride layer is between 0.25 mm and 0.45 mm, and the change of mold size after nitride should be within 0.02mm.

For solid profiles and hollow profiles with suspended walls on the section, the elastic deformation of the mold should also be considered, in order to ensure a certain stiffness of the mold, the thickness of the mold or special pads with similar shapes can be considered.

In order to control the change of profile opening size, a drainage channel can be opened on the mold to control the flow of metal.