A modern household refrigerator is a complex engineering structure, where each element performs a strictly defined function. The appearance and interior space are familiar to everyone, but few people think about what lies between the two visible layers. It is the internal structure of the case that ensures the preservation of cold, energy efficiency and durability of the entire system.
Understanding of this what are the walls of the refrigerator made ofis necessary not only for inquisitive users, but also for those who plan to repair or modernize equipment. Knowing the materials helps you properly care for the surface, avoid damage during transportation, and understand why you shouldn’t thoughtlessly drill holes in the body. The structure of the walls is a multilayer “pie” created taking into account the requirements of thermodynamics and safety.
In this article we will analyze in detail the composition of the external and internal panels, the types of insulating materials and the technological features of their connection. You will find out why manufacturers are abandoning some old materials and what new products are appearing in the premium segment. This knowledge will help you choose a reliable model and extend its service life.
External body: metal and decorative coatings
The outside of the refrigerator is its face and the first line of defense against external influences. The basis for the production of external walls is cold-rolled steel sheet. This material is not chosen by chance: it has high strength, rigidity and excellent stamping ability, which allows you to create cases of complex shapes without loss of geometry.
Metal thickness usually varies between 0.5–0.7 mm. This is enough to withstand the loads during operation, but without making the structure heavier. However, bare steel is susceptible to corrosion, so it undergoes multi-stage processing. First, the surface is degreased, then coated with a layer of zinc phosphate for adhesion, and only then the main protective and decorative layer is applied.
- 🎨 Polymer coating: the most common option is known as “powder painting.” Creates a matte or glossy texture that is scratch-resistant.
- 💎 Stainless steel: used in luxury models. Often has a special coating Anti-Fingerprintthat repels fingerprints.
- 🪵 Imitation materials: Modern technologies make it possible to apply the texture of wood, stone or leather to the metal, which fits the equipment into any interior.
It is important to note that the side walls in modern models are often heated. This is not a defect, but an engineering solution: condenser tubes are laid in thin-walled metal, which release heat to the environment. Therefore, the outer surface may be warm to the touch, especially in the hot season or when the compressor is actively operating.
Internal chamber: plastic and its varieties
If metal reigns outside, then inside the refrigerator rules the show. plastic. Internal walls, shelves and drawers are made of special polymers that must meet strict sanitary standards. The material must be inert, not absorb odors, not emit toxins upon contact with products and withstand temperature changes.
The main material for the production of the inner liner (liner) is ABS plastic (acrylonitrile butadiene styrene). It is characterized by high impact resistance and rigidity. However, ABS has a weak point - low frost resistance. When strongly cooled, this material can become brittle, so it is rarely used in freezers or in combination with other additives.
⚠️ Attention: When cleaning the interior walls of the refrigerator, it is strictly forbidden to use abrasive sponges, hard brushes or aggressive solvents (acetone, gasoline). ABS plastic is easily scratched, and bacteria instantly multiply in microcracks, and the tightness of the thermal insulation may also be broken if the damage is through.For freezer compartments and drawers, it is often used polystyrene. It is cheaper and holds low temperatures well without cracking in the cold. However, polystyrene is more fragile when subjected to mechanical shock (for example, if you drop a heavy frozen carcass) and can turn yellow over time under the influence of ultraviolet radiation if the refrigerator is located near a window.
Thermal insulation: the core of the refrigerator compartment
Between the outer metal shell and The inner plastic liner contains the most important layer - thermal insulation. It is the quality of this layer that determines how much electricity your refrigerator will consume and how quietly it will operate. The task of the insulator is to make it as difficult as possible for the heat exchange between the warm air of the kitchen and the cold inside the chamber.
For a long time, polyurethane foam (PPU)was the industry standard. This is a foamed polymer that is pumped in liquid form into the space between the walls, where it hardens, forming a monolithic structure with millions of microscopic cells filled with gas. Gas (formerly freon, now environmentally friendly cyclopentane or isobutane) has thermal conductivity several times lower than air.
Modern technologies make it possible to make walls thinner, maintaining or even improving the insulating properties. This is achieved through:
- 🧱 Vacuum panels (VIP): used in premium models. A board with a evacuated filler has a thermal conductivity 5-10 times lower than that of polyurethane foam, allowing the walls to be made very thin.
- 💨 Improved formulation PPU: use of gases with a lower thermal conductivity coefficient and control of the size of foam cells.
- 🛡️ Multilayer insulation: a combination of different materials to block all types of heat transfer.
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