The aluminum foil supplied by HDMETALM is always guaranteed Excellent coating performance, uniform mechanical performance, excellent processing adaptability and excellent hydrophilic environment characteristics.

Technical Specifications

Dimension

Foil category

Bare foil

REQUEST A QUOTE

Package

Why are more air conditioning manufacturers choosing to use hydrophilic foil?

Hydrophilic foil is the main raw material for heat exchangers in air conditioners, and is widely used in household air conditioners, refrigerated cabinets, automobile air conditioners and other refrigeration equipment,
and has the following advantages over ordinary light foil.

• It can increase the anticorrosive, anti-mold and odorless functions

• The condensate is evenly distributed on the surface of the heat exchanger sheet, so that the formation of water droplets will not cause blockage between the heat exchanger sheets and affect the efficiency of heat exchange, thus increasing the heat exchange rate by 5%.

• No noise caused by vibration is reduced due to the absence of water beads.

• It can prevent the air conditioner oxidation powder from blowing into the room to produce adverse effects on human body and meet the requirements of environmental protection.

What are the types of aluminum foil used for air conditioning?

Uncoated aluminum foil

Uncoated aluminum foil is aluminum foil that has been rolled and annealed without any form of surface treatment.

The aluminum foil used for air conditioning heat exchangers in China 10 years ago and abroad about 15 years ago are non-coated aluminum foil.
About 50% of the heat exchangers used in developed countries abroad are still non-coated aluminum foil, while in our country, the ratio is around 60%.

Coated aluminum foil

The so-called coated aluminum foil is the surface reprocessing of non-coated aluminum foil to make it have some special function.

In Japan, Germany and other countries with faster technology development, the use of coated aluminum foil has a history of more than 15 years. In China, coated aluminum foil has been used for no more than 10 years.

According to the characteristics possessed by the surface of coated aluminum foil, it can be further classified as follows.

• Corrosion-resistant aluminum foil

The surface of corrosion-resistant aluminum foil products has a certain corrosion-resistant protective layer, and the air conditioner heat exchanger made of this product can be applied to more severe areas and can significantly improve the service life of the air conditioner.

At the same time, due to the improvement of the corrosion resistance of the heat exchanger, the generation of surface corrosion powder is greatly reduced, thus improving the quality of ventilation and purifying the air inside the air conditioner.

• Hydrophilic aluminum foil

Hydrophilic aluminum foil surface has a strong hydrophilic.

The hydrophilic performance is determined by the size of the angle formed after the water sticks to the surface of the aluminum foil. the smaller the an angle, the better the hydrophilic performance, and vice versa, the worse the hydrophilic performance. Generally speaking, a-angle is less than 35, which is hydrophilic.

Hydrophilic aluminum foil is generally used in the evaporator of air conditioners. Its main function is to make the moisture in the hot air condense into water droplets on the heat exchanger easily spread out and flow down the sheet. This can avoid the water beads between the heat exchanger sheet “bridge” and affect the ventilation effect of the heat exchanger, thus improving the heat exchange rate of the air conditioner, in the same conditions of cooling capacity can also save electricity.

Before, the general hydrophilic aluminum foil on the market has a good hydrophilic surface, but also has a high corrosion resistance, so that the performance of the air conditioner is more optimized.

• Water-repellent aluminum foil

The Water-repellent aluminum foil has the opposite surface performance of hydrophilic aluminum foil. That is, condensate condensation to the surface of the aluminum foil and the aluminum foil into a larger contact angle, generally in the 75. above. The larger the angle, the better the water repellent performance.

The ultimate purpose of using water-repellent aluminum foil is the same as hydrophilic aluminum foil, i.e. not to let condensate stay between the heat exchangers.

The difference is that the water-repellent aluminum foil is to increase the contact angle between the condensate and the heat exchanger, so that the condensate forms water droplets that are easy to slip off and achieve the purpose of removing the condensate between the heat exchanger.

• Self-lubricating aluminum foil

The air conditioner heat exchanger sheet is generally processed and produced by adding lubricant to its surface first, then punching and turning the edge, and finally washing away the lubricant with [trichloroethylene]. Since trichloroethylene is harmful to humans, self-lubricating aluminum foil was created to reduce this process.

Self-lubricating aluminum foil, as its name implies, does not require separate lubrication during its punching process; the lubrication during punching is carried out by a pre-treated film on the surface of the foil. Since there is no need to add lubricating oil, the subsequent trichloroethylene cleaning and drying process is also eliminated.

• Anti-mold aluminum foil

The main function of anti-mildew aluminum foil is to prevent the surface of the heat exchanger from becoming mildewed due to the use or placement for a long time, thus obviously improving the ventilation quality of the air conditioner, preventing the generation of abnormal odor and effectively improving the indoor environment of the air conditioner.

When you purchase uncoated aluminum foil what technical specifications do you need to pay attention to from the suppliers?

Chemical composition

The alloy grades of aluminum foil for heat exchanger sheet are mainly 1100, 1200, 8011, etc.

In terms of use, air conditioners do not have strict requirements on the chemical composition of aluminum heat exchanger sheets. Without surface treatment, 3A21 aluminum alloy has relatively good corrosion resistance, high mechanical properties such as strength and elongation, and high hardness. Which alloy is chosen depends mainly on the final mechanical properties that the material can achieve and the ease of the rolling process. Such as higher purity of 1100 aluminum alloy calendering is easier, while 8011 alloy is more difficult.

Mechanical properties

Mechanical properties mainly refer to the tensile strength, elongation and cupping value of aluminum foil. From the use point of view, we hope that these three indicators are as high as possible, but as far as the material itself is concerned, these three indicators are contradictory to each other, that is, when the tensile strength of aluminum foil is relatively high, the elongation indicator will drop; and when the elongation of aluminum foil is increased, it will cause a drop in tensile strength.

Therefore, in practice, the middle value of mechanical properties is generally taken, while the specific strength and plasticity values are related to the processing of heat exchanger sheet punching die. The general heat exchanger sheet punching processing is divided into two types of tensile and non-tensile. Stretching type processing molds require better plasticity of aluminum foil, i.e. higher elongation rate, and slightly lower relative strength value; while non-stretching type molds require higher strength of aluminum foil, and plasticity is a secondary indicator.

There are many factors affecting the mechanical properties of aluminum foil, mainly the chemical composition and processing process 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 made to change within a certain range while keeping one side unchanged. In other words, the strength and plasticity of aluminum foil can be changed to a limited extent by adjusting the chemical composition and processing process.

According to the different mechanical properties required by heat exchangers, there are three main states of aluminum foil: H22, H24 and H26. Each state corresponds to a certain range of strength and plasticity. From the current situation of the domestic aluminum processing industry, there is no unified standard for the range of mechanical properties of each state. At the same time, the range of mechanical properties of each state is too wide in practical application, and the mechanical properties of the products cannot be well controlled to achieve the degree of satisfaction of users.

When you purchase coated aluminum foil (hydrophilic foil)what technical specifications do you need to pay attention to from the suppliers?

Coated aluminum foil is formed after surface treatment on the basis of uncoated aluminum foil. In addition to the above-mentioned performance indicators such as chemical composition, mechanical properties and geometric dimensions required for non-coated aluminum foil, it should also have good plate shape and coating properties.

Flatness of aluminum foil

First of all, the production process of coated aluminum foil requires a good plate shape, which is a prerequisite for the production of coated aluminum foil. The unit of measurement of plate shape is I. The general requirement of coating production equipment for plate shape is within 20-40 I. If it is greater than this value, a tension straightening system should be added in front of the coating equipment. The general coating equipment has a long aluminum strip running route and more handling processes and guide rollers.

Therefore, if a tension straightening system is not provided, it will be easy to fold the foil during operation if the sheet shape is not good, making production impossible. The production process of air conditioners also has high requirements for the sheet shape of aluminum foil. The general heat exchanger sheet punching production line uses the vacuum suction method for aluminum foil transfer. If the sheet shape of aluminum foil is not good and the surface is not flat, it will lead to the vacuum suction method of aluminum foil transfer cannot be carried out properly. Therefore, the plate shape is an important technical indicator not only for coated aluminum foil but also for uncoated aluminum foil.

Coating performance

As mentioned earlier there are many kinds of coated aluminum foil for heat exchangers, and the coated aluminum foil currently used in the market is mainly hydrophilic aluminum foil, so only the coating performance index of hydrophilic aluminum foil is discussed here.

Coating thickness

There is no hard rule on the thickness of coating film on the surface of aluminum foil, which is generally below 3/1m. Since the price of coatings is generally more expensive, the thinner the coating thickness is controlled to meet the performance requirements, the lower the production cost.

Coating thickness directly affects the performance index of the coating, so the coating thickness of the aluminum foil surface is required to be uniform and consistent.

Coating adhesion

Coating adhesion is an indicator of how well the aluminum foil is bonded to its surface coating. If the coating adhesion is too small, the coated aluminum foil will easily fall off the surface coating film in further processing and use, which will seriously affect the weight of the coated aluminum foil, so the stronger the coating adhesion, the better.

The coating adhesion can only be detected qualitatively, and the main detection methods are abrasion test, scratch test and cup protrusion method.

Hydrophilic performance

Hydrophilic aluminum foil will be affected by various environmental factors after a period of use.

Therefore, hydrophilicity is generally divided into initial hydrophilicity and hydrophilicity after environmental test. The hydrophilicity is mainly measured by the size of the a-angle. The initial hydrophilicity of general products requires a<100, and the hydrophilicity after the environmental test requires a<250. The measurement of contact angle a can be chosen from a special contact angle measuring instrument; it can also be calculated by the size of the area occupied by a certain volume of water drops on the surface of aluminum foil.

Corrosion resistance

Corrosion resistance is mainly reflected in three aspects:

First, alkali resistance, because the lubricant on the surface of the heat exchanger after punching needs to be removed with alkaline cleaning agent, so the functional coating on the surface of the aluminum foil must have a certain degree of alkali resistance, generally requiring 3 minutes of immersion in a 20% NaOH solution without blistering;

second, salt spray corrosion resistance, generally in the test conditions of 35 oC, 3% of the salt water spray environment requires 500 hours can not have corrosion spots. The good or bad salt spray corrosion resistance is directly related to the length of service life of the heat exchanger. In coastal areas, due to the high salt content in the air, so the heat exchanger salt spray corrosion resistance has higher requirements;

third is the resistance to heat and humidity performance, that is, in a certain temperature, a certain humidity placed under a long time corrosion resistance. This performance is also an important indicator of the weather resistance of the heat exchanger.