Aluminum foil is widely used to make heat conduction fins due to its low density, good thermal conductivity, easy processing and cheap price. The common alloys of air conditioner aluminum foil tape are 1100, 1200, 3003, 8011, etc. The tempera are H22, H24, H26. The thickness range is 0.08 to 0.2mm.
There are certain differences in the strength and plasticity of each state. The choice of which alloy grade or which state of aluminum foil to choose depends on the actual situation. From the point of view of use, air conditioners have no strict requirements on the chemical composition of aluminum heat exchanger fins. Without surface treatment, 3A21 aluminum alloy has relatively good corrosion resistance, high mechanical properties such as strength and elongation, and high hardness.
Which alloy to choose mainly depends on the final mechanical properties that the material can achieve and the processing difficulty. For example, the rolling of 1100 aluminum alloy with higher purity is easier, while that of 8011 alloy is more difficult.
Mechanical properties mainly refer to the tensile strength, elongation and cupping value of aluminum foil. From the perspective of use, it is hoped that the higher the three indicators, the better. As far as the material itself is concerned, these three indicators are contradictory, that is, when the tensile strength of the aluminum foil is relatively high, the elongation index will decrease; and when the elongation of the aluminum foil is increased, the tensile strength will decrease.
Therefore, in practical applications, the intermediate value of mechanical properties is generally taken, and the specific strength and plasticity values are related to the stamping die during heat exchange fin processing.
Generally, the punching process of heat exchange fins is divided into stretching type and non-stretching type. Stretch-type punching molds require better plasticity of aluminum foil, that is, higher elongation, and the relative strength value can be slightly lower; while non-stretch molds also require higher strength of aluminum foil, and plasticity is a secondary indicator.
There are many factors that affect the mechanical properties of aluminum foil, mainly the chemical composition and processing technology of aluminum foil. As far as the strength and plasticity of aluminum foil are concerned, by adjusting the chemical composition or changing the processing process and parameters, the plasticity or strength of the material can be changed within a certain range while keeping one side unchanged. That is to say, the matching value of aluminum foil strength and plasticity can be limitedly changed through the adjustment of chemical composition and processing technology.
Coated aluminum foil is used as a fin heat exchanger, and there are generally two types: one is normal hydrophilic aluminum foil (blue), and the other is corrosion-resistant hydrophilic aluminum foil (gold).
The normal hydrophilic aluminum foil for aircon is painted blue. This painted aluminum foil makes it impossible for condensed water to form ice bridges. This blue hydrophilic aluminum foil is generally used in the production of small heat exchangers. The high corrosion resistance hydrophilic aluminum foil coated with gold is an excellent solution in terms of corrosion resistance, the epoxy resin provides the required protection to the aluminum foil in a wide range.