When choosing new household appliances, consumers often pay attention to functionality, chamber volume and design, but rarely think about the physical composition of the unit. The question of what kind of metal in the refrigerator is used in production becomes relevant if the case is damaged, the need for painting or disposal of the device. Understanding the chemical composition of materials helps to assess the durability of equipment and its resistance to corrosion.
A modern refrigeration unit is a complex composite, where each element plays its role, and metals occupy a dominant position in terms of mass. From the steel body to the copper heat exchanger tubes, all materials are selected by engineers taking into account thermal conductivity, strength and cost. In this article, we will analyze in detail what alloys your household assistant is made of and how this affects its operation.
Knowing the type of metal is important not only for theoretical curiosity, but also for practical application. For example, when transporting, it is important to know that the outer casing is thin steel, which can be easily damaged by a sharp object, while the inner shelves can be made of aluminum or plastic. Let's dive into the world of metallurgy of household appliances.
⚠️ Attention: The composition of materials may vary slightly depending on the manufacturer, model year and price segment. The data below is average for the industry.
Main body: steel and its coatings
The vast majority of the outer walls of the refrigerator that we see in the kitchen are made of cold-rolled steel. This material was not chosen by chance: it has high strength, rigidity and, importantly, magnetic properties, which allows you to attach magnets or spice holders to the door. However, “bare” steel quickly rusts, so it always undergoes multi-stage processing.
First, the steel sheet is coated with a zinc layer during the galvanization process, which creates a barrier to corrosion. Then a layer of primer and a finishing polymer coating is applied, which we see as colored or white enamel. It is this outer layer that protects the metal from moisture, grease and mechanical scratches. Premium models, especially those with a stainless steel coating, use AISI 430 stainless steelwhich contains chromium, which gives it shine and resistance to oxidation.
- 🏗️ Structural strength: Steel ensures structural rigidity, protecting the insulation and compressor from external shocks.
- 🛡️ Anti-corrosion protection: Zinc plating and polymer paint prevent rusting even in a damp kitchen environment.
- 🧲 Magnetic properties: Ferromagnetic steel allows the use of magnetic accessories on the door.
Sometimes in budget models or in hidden places (back wall, sides, hidden from view) thinner metal or even durable composite materials can be used, but the main mass is always steel. The thickness of the sheet usually varies from 0.5 to 0.8 mm, which is a compromise between the weight of the device and its strength.
Interior: plastic or metal?
Looking inside the refrigerator compartment, the user most often sees a white, smooth material. In the vast majority of modern models, the inner liner is made of ABS plastic (acrylonitrile butadiene styrene) or polystyrene. These materials are hygienic, easy to clean, do not absorb odors and are sufficiently durable at low temperatures. However, this was not always the case, and in some specific models metal is still found.
In old Soviet refrigerators or in professional commercial equipment, the internal chamber could be made of aluminum or stainless steel. Aluminum has excellent thermal conductivity, which played a key role in drip defrosting systems (“crying evaporator”): the back wall cooled and thawed evenly. In modern household appliances, the metal inner chamber has been abandoned in favor of plastic due to its cheapness, lightness and better thermal insulation.
⚠️ Attention: If you find a metal back wall inside the refrigerator, most likely it is either a very old model or professional cabinet. Be careful when cleaning: aluminum can easily be rubbed to holes with abrasive sponges.
The shelves inside the chambers are also rarely metal. Most often this is tempered glass or lattice plastic. Metal shelf guides are usually made of chromed steel or aluminum, but they do not come into direct contact with the products, being in special grooves.
Why was the metal inner box abandoned?
The metal liner (aluminum) had high thermal conductivity, which led to cold losses if the insulation was not ideal. In addition, the metal clanged when the dishes were placed, was cold to the touch and was prone to dents. Plastic decided to become warm, quiet and impact-resistant.
Cooling system: copper, aluminum and steel
The very heart of the refrigerator, hidden from the user’s eyes, is a complex system of tubes and heat exchangers. There are different metals used here, each with its own unique properties. The main material for pipelines through which refrigerant circulates has long been copper. It has excellent thermal conductivity, ductility and corrosion resistance.
However, in modern models, especially in the budget and mid-range segment, copper is often replaced with aluminum. Aluminum tubes are lighter and much cheaper, but they are more fragile and susceptible to galvanic corrosion when in contact with other metals. The joints between copper and aluminum parts are made using special adapters to avoid destruction of the system.
The evaporator (what freezes) and the condenser (what heats from behind) can be made in the form of foamed aluminum plates or steel tubes with aluminum fins. In some No Frost systems, a fan drives air through an aluminum evaporator radiator, which is hidden behind a plastic panel.
- 🌡️ Thermal conductivity: Copper and aluminum were chosen for their ability to quickly transfer and receive heat.
- 💰 Economic efficiency: Replacing copper with aluminum reduces the cost of the final product.
- 🔄 Flexibility: The softness of metals allows the formation of complex coils without creases.
The compressor, which is the engine of the system, also contains a lot of metal: copper in the windings of the electric motor, steel in the housing and valves. It is the compressor that makes up a significant part of the weight of the entire unit.
Comparison of metals: characteristics and purpose
To better understand why such a set of materials is used in the refrigerator, consider their properties in comparison. Each element is selected by engineers to perform a specific task: somewhere strength is needed, somewhere thermal conductivity, and somewhere lightness.
Below is a table showing the distribution of metals among refrigerator units and their main characteristics:
| Refrigerator unit | Basic material | Key property | Weight fraction |
|---|---|---|---|
| External body | Steel (galvanized) | Strength, rigidity | ~40-50% |
| Pipelines | Copper / Aluminum | Thermal conductivity | ~5-8% |
| Compressor | Steel, Copper | Wear resistance | ~15-20% |
| Fasteners and hinges | Steel | Reliability | ~2-3% |
As can be seen from the table, steel dominates in weight, ensuring the integrity of the structure. However, without copper and aluminum in the refrigerant circulation system, the refrigerator will not be able to perform its main function - to cool food.
Problems and care of metal parts
Despite the protective coatings, the metal in the refrigerator requires careful handling. The main threat to a steel case is mechanical damage to the enamel. a chip or deep scratch, moisture from the air begins to come into contact with the base, starting the corrosion process. Rust under the paint can swell the coating, making the defect noticeable and dangerous for the integrity of the wall.
To clean external metal surfaces, especially those imitating stainless steel, do not use abrasive powders, hard brushes or aggressive solvents (acetone, gasoline). These substances destroy the protective polymer layer. It is recommended to use special products for stainless steel or a mild soap solution, wiping the surface with a soft flannel cloth along the texture of the metal.
⚠️ Attention: Never use chlorine-containing products (for example, "Whiteness") to clean the metal surfaces of the refrigerator. Chlorine destroys the passive protective layer on stainless steel, causing pitting corrosion that cannot be eliminated.
If you notice blistering of the paint on the body, this is a signal that the metal underneath is already oxidizing. In this case, it is necessary to clean the damage to bare metal, treat it with a rust converter and paint it with special enamel to stop the spread of corrosion.
Disposal: the value of scrap metal
When the refrigerator has served its useful life, the question of disposal arises. Since the device consists primarily of metal, it is of interest to recycling collection points. However, simply handing it over as “black scrap” would be a mistake from a financial point of view.
The refrigerator contains non-ferrous metal (copper, aluminum), which is valued on the scrap market much more expensive than black steel. The compressor contains copper windings, the tubes can be copper, and the radiators can be aluminum. With proper disassembly, you can remove these components and hand them over separately, receiving more money than for handing over the whole unit.
However, it is worth remembering environmental safety. There is a refrigerant inside the cooling system, and the insulating layer (foam) may contain freons, which destroy the ozone layer. Therefore, independent sawing of the body with an angle grinder is strictly prohibited without observing safety measures and the presence of filters.
☑️ Preparing the refrigerator for scrapping
Frequently asked questions (FAQ)
Is the body of a stainless steel refrigerator magnetic?
It depends on the grade of steel. If ferritic stainless steel (400 series) is used, the magnets will stick. If it is austenitic (300 series, more expensive and resistant to corrosion), then the magnetic properties will be weak or absent. Most household refrigerators with a metallic coating are magnetic.
Is it possible to paint a refrigerator with regular paint?
Theoretically, it is possible, but regular paint will not adhere to smooth factory enamel and may crack from vibration and temperature changes. It is recommended to use automotive enamels or special paints for household appliances, having previously primed the surface.
Why does the back wall of the refrigerator rust?
The back wall is often exposed to moisture (condensation, floor washing) and heat from the condenser. If the factory zinc coating is damaged during transportation or production, the steel begins to oxidize. Also, the reason may be high humidity in the room.
How much does the metal body of the refrigerator weigh?
The weight of the metal is approximately 60-70% of the total weight of the refrigerator. For example, if a refrigerator weighs 70 kg, then the share of metals (steel, copper, aluminum) is about 45-50 kg. The rest is plastic, glass, insulating foam and refrigerant.
Is aluminum inside the refrigerator harmful to food?
In modern refrigerators, food does not come into direct contact with aluminum. Aluminum evaporator tubes are foamed in the housing or hidden behind a plastic panel. Direct contact of products with aluminum is possible only in older models, but aluminum oxide itself is inert and safe under normal operating conditions.