Several small metal pieces are crucial parts in refrigeration equipment that are hardly noticed until they break. Flat sheet metal is used to make a variety of different parts that are precisely formed to perform their specified function, including brackets that hold a compressor in place, a cabinet’s panels, clips for tubing, and heat exchanger fins. This forming process is called metal stamping and is more involved in the production of refrigeration.
Whether you are designing, sourcing, or manufacturing refrigeration equipment, if you understand the manufacturing process, know which materials are best suited, and how to select a manufacturing partner, you will save time and money.
What Stamped Metal Parts Are and Why Refrigeration Equipment Needs Them
Metal stamping is a manufacturing technique in which a flat sheet of metal is inserted into a press and formed into the desired shape with the help of a die. The press is used to exert force on the metal to create a desired shape by cutting, bending, punching, or forming. Fast, repeatable, and scalable, whether you’re producing hundreds or millions of identical parts.
It is quite simple, but stamped parts are vital to refrigeration systems. These systems consist of numerous small parts requiring strength and flexibility, light weight, corrosion resistance, and dimensional uniformity. All of that can be achieved for a lower cost than machining or casting, particularly for parts of volume.
Stamped parts can be seen in any refrigerator, freezer, air conditioning system, or commercial cooling system. They keep everything in place, prevent damage to internal parts, guide airflow through the unit, and provide support for the tubing used to circulate refrigerant throughout the system.
Where Stamped Metal Parts Show Up in Refrigeration Assemblies
Stamped parts are used in almost every part of a refrigeration unit. Examples of this are the following:
- Cabinet panels and enclosures. The exterior shell of refrigerators, freezers, and other commercial coolers is typically stamped sheet metal, usually galvanized or coated with paint to protect it.
- Installing brackets and chassis components. Whether it is a compressor, fan, or control board, they all require something to hold them in place. Stamped brackets are inexpensive, lightweight, and strong in large volume.
- Heat exchanger components. Fins, plates, and mounting tabs used in evaporators and condensers are typically stamped from thin aluminum or copper for good heat transfer.
- Clips and fasteners. Tubing clips, retaining clips, and spring clips used to keep refrigerant lines and wiring secured are typically stamped from spring steel or stainless steel to provide a consistent holding power over time.
- Structural frames, bases. For larger refrigeration units such as commercial walk-in coolers, stamped steel frames and bases are used to support the units.
- Some terminals and electrical connectors. In the electrical section of refrigerating systems, the conductivity of copper or brass stamped parts is important.
Materials Commonly Used for Stamped Refrigeration Components
Consider the type of material used in a part for factors such as cost, weight, resistance to rusting in moist or cold conditions, and more. Here is a breakdown of the most common materials for stamped parts used in refrigeration equipment.
Cold rolled carbon steels (SPCC, SPCD, DC01-DC06): This is one of the most popular materials for stamped parts, as it is affordable, easy to form, and weld. It is suitable for brackets and structural components but is not corrosion resistant and should be treated for rust.
Hot rolled carbon steel (Q235B, Q345B, SS400): For thicker and heavier duty parts such as frames and bases. It has good strength but is easily oxidized, so it is generally required to be treated on the surface.
Stainless Steel 304 and 304L: A “go-to” choice if corrosion is an important criterion, as it is with refrigeration because moisture and condensation are always factors. It is also food safe, so it can be used for parts in proximity to refrigerated food storage.
Stainless steel 316L: Offers even better resistance to corrosion, including acidic and alkaline conditions. It is typically used for parts that will be cleaned with chemicals or in a more humid environment.
Aluminum alloy 5052. It is used for cabinet panels and casings due to its good rust resistance and easy forming characteristics.
Aluminum alloy 6061: A versatile structural aluminum for use in applications where structural strength and light weight are both important, sometimes anodized for enhanced corrosion resistance and durability.
Galvanized steel (SECC, SGCC, DX51D): It is often used in appliance casings and cabinets, as the surface is coated with zinc, giving it built-in rust protection at a medium price.
Galvalume (AZ150): It offers greater weather resistance than standard galvanized steel, which can be used for an outdoor refrigerator cabinet or unit that is exposed to the elements.
Copper and brass: Copper’s excellent thermal and electrical conductivity makes it ideal for condenser and evaporator fins, as well as electrical connectors and electrical components. Connectors and terminals are frequently manufactured from brass material, which can be plated for enhanced appearance and corrosion resistance.
Spring steel (65Mn, SK5, 60Si2Mn): Needed to maintain shape and springiness over the years of use, as it is important to be able to keep tubing and components in a refrigeration unit.
The material selection is dependent on the cost, strength, corrosion resistance, and application of the part. There are differences in the requirements of a cabinet panel versus a spring clip supporting a refrigerant line, and it should always begin with the function of the part in question.
How the Stamping Process Works for Refrigeration Parts
The stamping process consists of several stages; the sequence of the stamping process depends on the complexity of the part.
Blanking
A flat piece of metal is cut to a simple form, generally referred to as a blank, with a simple die that forms the outline of the part.
Piercing and Punching
Holes, slots, and cutouts are included to accommodate screw attachment or tubing or other assembly requirements.
Bending and Forming
The flat blank undergoes bending and shaping to form the final product. This step is used to define whether the final geometry is a simple bend, a multi-angle bend, or a more complex shape.
Deep Drawing
When parts must have a dimensional depth, such as some casings or housings, the metal is pulled into a cavity of the die in a 3D shape without cutting the metal.
Finishing
Edges are deburred, and required surface treatment, plating, or coating is applied.
Progressive die stamping is typical for high-volume refrigeration components. In this technique, the metal is fed to a series of stations in a single stroke, performing a number of operations in a single press. It is efficient and maintains a high part-to-part consistency, which is very important when thousands of identical brackets or clips are required to be placed in the same assembly line without adjustment.
Precision and Tolerances in Refrigeration Stamping
When refrigeration assemblies require a tight fit—particularly when components are attached to tubing, compressors, or sealed enclosures—it can be challenging. A slightly loose bracket may not fit properly, and an imperfect panel may have a gap that will impact insulation or airflow.
The choice of tolerance control is as important as the choice of materials. Typically, manufacturers check dimensional accuracy by taking measurements with a calliper or coordinate measuring machine and with a go and no-go gauge to ensure that all parts in a batch are within the design specification. Good tool maintenance and the calibration of presses also contribute to the maintenance of tolerances over extended production runs.
Surface Treatments That Protect Against Corrosion
In refrigeration environments moisture, temperature fluctuation, and possibly cleaning agents can speed up corrosion rates on untreated metal. The following are some of the more popular surface treatments that increase part life:
Zinc plating or galvanizing provides a protective coating that gives up to the base material to prevent rust. The quality of the powder coating provides durability and water resistance and also makes it resistant to water. Stainless steel parts are usually passivated to eliminate surface contaminants and enhance natural corrosion resistance.
Many aluminum components are anodized to give them a hard oxide coating, which enhances their appearance and wear resistance. Many cabinet panels and enclosures can be painted in an easy, inexpensive manner, especially when they are made of carbon steel.
The selection of a correct treatment will depend on the location of the part within the system and the moisture and/or temperature exposure.
Quality Standards and Inspection for Stamped Refrigeration Parts
Reliable refrigeration equipment depends on parts that meet specifications every single time, not just on the first article sample. Good manufacturers typically adhere to standards like ISO 9001, general quality management, and a number of refrigeration components are required to comply with material standards like RoHS (restricted substances) standards, particularly if the product is exported internationally.
Typical inspection methods include first article inspection before full production begins, in-process checks during the stamping run, and final inspection before parts ship. Caliper, micrometer, and coordinate measuring machines verify dimensions, and visual examination identifies surface irregularities, burrs, scratches, or inconsistencies in the coatings. Some manufacturers also employ analytical process control to monitor the measurement of a part throughout a production run to detect drift before it causes a problem if there are tighter tolerances.
Choosing a Manufacturing Partner for Stamped Refrigeration Parts
Not all stamping shops have equipment that is compatible with refrigeration components. Check the manufacturer’s experience in the materials they use for refrigeration applications and quality systems, and provide a clear understanding of tolerances, lead times, and material certifications. Requesting to view sample parts, past project references, and quality documentation can provide you with a lot of information before committing to a production run.
FAQ
What materials are most commonly used for stamped components in refrigeration assemblies?
Cold rolled and galvanized carbon steel are common materials used in making cabinets, brackets, and structural components due to their low cost and malleability. The corrosion resistance properties of stainless steels (304 and 316L) are selected where protection from corrosion is particularly important, whereas aluminum alloys such as 5052 and 6061 are selected where lightweighting requirements are paramount. Copper and brass are found in heat exchangers and electrical connectors, as well as spring steel used in clips that have a longer life span.
How do I choose a qualified manufacturer for precision-stamped refrigeration components?
Check with the manufacturer for direct experience in manufacturing parts in the material types you need, an ISO 9001 quality system, and tooling and equipment that can meet your required tolerances. Also, check through previous work, asking what their inspection process is and checking if they have material certifications if required.
What tolerance ranges are typical for stamped parts used in cooling and refrigeration equipment?
Tolerances vary depending on the part and its function, but many stamped refrigeration components are held to within a few hundredths of a millimeter for critical dimensions, while less critical features may have wider allowances. The right tolerance depends on how the part fits with surrounding components, so it is best defined during the design stage with input from your manufacturer.
Which surface treatments and coatings help prevent corrosion in refrigeration environments?
Zinc plating, galvanizing, powder coating, and passivation are among the most common treatments. Zinc-based coatings protect carbon steel parts, passivation improves the natural resistance of stainless steel, and anodizing is often used on aluminum components. The right choice depends on the base material and how much moisture exposure the part will face.
What quality standards and inspection methods are used to validate stamped components for refrigeration systems?
Most manufacturers will conform to ISO 9001 quality management processes and could even adhere to material standards like RoHS. Inspection will entail initial inspection of the first article, in-process inspection, and then finally a dimension verification through use of instruments such as micrometers and measuring machines.
Work With a Trusted Stamping Partner
Though stampings may seem small, they play a crucial role in the performance and durability of a refrigeration unit. By selecting the correct material, tolerance, and surface treatment at the initial stages, you will avoid expensive work later on.
FST Metals is a company that manufactures precision stamped metal parts intended for use in tough environments, such as refrigeration units. Having vast experience working with different metals, FST Metals can assist you in bringing your design to fruition. Check out our website at fstmetals.com to get your free quote.
