Aluminum cross-sections (profiles) for the manufacture of frames are produced by various companies in a wide variety of shapes, dimensions and weights (each manufacturing company has patented its own type of cross-sections). Production takes place in series of specialized cross-sections intended for the manufacture of predetermined types of frames (ie doors or windows of a specific form and function, heavier or lighter type). An aluminum frame is assembled from cross-sections of a certain series and, as a rule, a frame cannot be made from cross-sections of different series or different companies. Aluminum frames are very light, but show less impact resistance than iron ones, due to the hollow configuration of the cross-sections and their relatively small thickness. Two important characteristics of the material that have an impact on the behavior of the frame are the high thermal conductivity and the high coefficient of thermal expansion.
The thermal conductivity of aluminum is three times that of steel. Therefore, significant heat losses are created through the cross-sections of the aluminum. A result of the high thermal conductivity are the very cold (during the winter) surfaces of the cross-sections which favor the intense condensation of water vapor on their surface. In order to solve the problem of the low thermal resistance of the common cross-sections, special cross-sections can be used which are interrupted (the inside from the outside part) by the insertion of synthetic heat-insulating material (heat-breakable profiles).
The large coefficient of thermal expansion leads to intense movements of the frame and leaf, especially in large-sized frames. Therefore, in the latter case, appropriate expansion joints must be provided. In addition to its natural color, it can easily be colored with various and impressive organic colors, unchanged by light and atmospheric corrosion by electrostatic painting.
The simplicity of applying aluminum in the construction of the frames and the wide variety of construction cross-sections (profiles) and components offered by the production companies, allow aluminum frames, in addition to their great solidity and mechanical resistance, to ensure much better tightness in air and water, from all other frame production materials.