Calculation of die hole size, chemical composition, main product is extruded alloy shape and nominal size and library allows tolerance, hot die material and is extruded alloy temperature and this temperature expansion coefficient of extrusion, product section geometry features and changes in the extrusion and stretching and straightening the size and extrusion mould the pressure of the plastic deformation and other factors.

The great difference of wall thickness profile, it is difficult to forming thin sections and sharp edge areas should be appropriately increased in size, width to thickness ratio of die hole wide and thin-walled profiles and the profile panel, stringer portion size can be designed according to the general type, and the web thickness dimensions, in addition to considering the factors listed in the formula besides, it is necessary to consider the factors of copper elastic deformation and plastic deformation and bending and extrusion cylinder center distance and distance. In addition, the extrusion speed and the I device with or without a bow have a certain influence on the size of the die hole.