In the vast field of manufacturing, sheet metal fabrication occupies an extremely important position. Sheet metal, which is made of various metals and comes in diverse thicknesses and forms, has a long and storied history. From the exquisite jewelry in ancient Egypt to the sturdy armor in the Middle Ages, its presence has run through the long history of human craftsmanship. Since the Industrial Revolution, it has achieved rapid development by virtue of its own advantages and has now widely penetrated into numerous industries.

The Mysterious World of Sheet Metal Fabrication Technologies

Cutting Processes

Cutting is a crucial initial step in sheet metal fabrication. Shearing was once a traditional cutting method, but due to its limitations in efficiency and precision, it has gradually been replaced by more advanced techniques. Punching, on the other hand, performs excellently in cutting metal by using a punch press and dies. It is particularly suitable for quickly forming simple parts and is also highly efficient in punching holes. Moreover, when combined with laser cutting, it can create complex and delicate patterns. Laser cutting is undoubtedly a star technology in modern sheet metal cutting processes. It uses various gas lasers to precisely carve out clean edges on the metal without the problem of tool wear. Different types of lasers can achieve excellent cutting performance for different thicknesses and materials of metal. Photochemical machining, taking a different approach, skillfully removes metal through chemical etching with the help of CAD-generated templates, showing unique process charm.

Bending Processes

Bending processes endow sheet metal with a rich variety of shape changes. In terms of straight-line bending, most metals can be bent along a straight axis under the action of various presses, and the bending shapes are extremely diverse. Press brakes are good at creating sharp bending effects, while rolling and forming methods can shape continuous single-axis curves, adding unique line aesthetics to sheet metal products. The hemming process focuses on enhancing the strength of the metal edge and is divided into two types: open and closed hemming. Moreover, hemming can also create a rounded edge to meet specific functional requirements, such as playing a key role in occasions where a smooth transition or enhanced structural stability is needed.

The Diverse World of Sheet Metal Materials

Stainless Steel

The stainless steel family is rich in variety. The standard stainless steel includes the 300 series (non-magnetic) and the 400 series (magnetic). Among them, 316-grade stainless steel stands out for its excellent corrosion resistance and good high-temperature strength, and is widely used in many environments with strict corrosion resistance requirements. 304-grade stainless steel is renowned for its outstanding formability and weldability and has become one of the most widely used stainless steel varieties. In the 400 series, 410-grade stainless steel can be further enhanced in performance through heat treatment, and 430-grade stainless steel, with its relatively low cost, occupies a place in application scenarios where the corrosion resistance requirement is not so high. In addition, spring-like stainless steel, due to its special performance characteristics, requires special equipment and processes to achieve the desired manufacturing effect during processing.

Cold Rolled Steel (CRS)

Cold rolled steel is mainly used to improve the surface finish and forming accuracy of hot rolled steel. Among its family, 1008 and 1018 alloys are common choices and play an important role in meeting specific manufacturing needs.

Pre-plated Steel

Pre-plated steel includes hot-dip galvanized steel and galvannealed steel. These pre-plating treatments can provide an additional protective layer for the steel, effectively enhancing its corrosion resistance and enabling it to maintain good performance in various environments.

Aluminum Alloy

Aluminum alloy is favored in sheet metal fabrication due to its moderate price, light weight, high strength, and good corrosion resistance. Different grades of aluminum alloy can accurately meet the application requirements of different fields, from daily necessities to industrial equipment, providing strong support for the lightweight and high-performance of products.

Copper/Brass

In the category of copper/brass, electrolytic tough pitch (ETP) copper is often chosen by designers because of its good conductivity and processing performance. Cartridge brass, on the other hand, may play a unique role in some specific designs, adding a different texture and functional characteristics to the product.

Key Considerations in Sheet Metal Design

Process Characteristics

Sheet metal fabrication is a non-additive and non-subtractive manufacturing process, which determines that the thickness of the part remains basically constant during manufacturing. Of course, in special cases, the thickness can be increased by welding, etc., but this will undoubtedly bring a significant increase in cost. Therefore, this factor needs to be fully considered at the beginning of the design.

Design Guidelines

When designing sheet metal parts, a series of guidelines need to be followed to ensure the manufacturability and quality of the product. First of all, universal tool configurations should be adopted as much as possible. For complex parts, the parts manufactured by universal tools can be combined by welding or riveting. In the design of bends, a specific distance needs to be maintained between the features and the bends. For example, following the 4T principle can effectively avoid deformation problems during manufacturing. Due to the limitations of the working method of the press brake, special caution is required when creating closed geometries in the design. Compared with machining and 3D printing, the tolerances of sheet metal are relatively loose and are comprehensively affected by various factors such as materials and manufacturing processes. However, suppliers usually provide relevant tolerance information for design reference. To simplify the production process, a single part should adopt a unified bending radius as much as possible, such as 0.030 inches. At the same time, maintaining a standard distance (4 times the material thickness) from the bend to the edge is also an important design point. In terms of assembly, welding thin materials is prone to problems such as deformation and insufficient welding strength. Therefore, other assembly methods such as riveting or using PEM hardware can be considered. When using PEM hardware, the requirements of the manufacturer for the installation position and material thickness must be strictly followed to ensure its normal operation.

The Art of Sheet Metal Surface Finishing

Purposes

There are two main purposes of sheet metal surface finishing. One is to protect the material from corrosion and extend the service life of the product; the other is to meet the aesthetic needs and enhance the visual attractiveness of the product. In many cases, a surface finishing method can achieve both purposes simultaneously, mainly through direct changes to the metal surface or the application of other materials and processes.

Specific Finishing Methods

The sandblasting process uses abrasive jets to clean and roughen the metal surface. This treatment method is widely used in the surface treatment of stainless steel and carbon steel and is often used as a pretreatment step before painting to provide a good surface foundation for the subsequent painting process. The brushing process uses abrasive brushes to clean and score the metal surface. This unique surface treatment method is common in aluminum and stainless steel products and can directly serve as the final surface treatment in many cases, showing a low-key and delicate texture. The polishing process can give the metal surface a bright and lustrous effect and is often used for stainless steel, aluminum, and copper. It can be used as the final surface treatment method or as a preparatory step for other surface treatments (such as electroplating). However, it should be noted that the polishing treatment is not suitable for metals that need to be painted. The powder coating process uses the method of electrostatically applying dry powder and then curing with heat. The surface treated in this way is more durable than traditional paint and can maintain good performance in relatively harsh environments, but it may be slightly inferior in aesthetics. The electroplating process includes various methods such as electrolytic plating and electroless plating and can achieve multiple functions such as corrosion prevention, improved solderability, and surface hardening. The specific processes include passivation, chromate coating, anodizing, galvanizing, nickel plating, tin plating, etc. Each process is targeted at specific needs and metal materials, providing a comprehensive solution for improving the surface performance of sheet metal products.

Strategic Considerations in Choosing Sheet Metal Fabrication

When deciding to adopt the sheet metal fabrication method, a rigorous design process is required. First, the preliminary design plan should be determined based on the functional requirements of the product. Then, when choosing materials and specifications, a delicate balance needs to be struck among factors such as strength, weight, and cost. In this process, CAD models and finite element analysis (FEA) tools can be used to optimize and verify the design. The prototyping and testing stages are crucial as they can help identify potential problems in the design and make timely adjustments. It is worth noting that even after the design is completed, the production methods and costs offered by different suppliers may vary significantly. Therefore, it is necessary to request quotations from multiple suppliers and make a comprehensive comparison to select the most suitable partner to ensure that the product can be produced with the best quality and cost-effectiveness.

The Wide Range of Applications of Sheet Metal Fabrication

Products fabricated by sheet metal are ubiquitous in our daily lives and industrial production. In the automotive field, numerous car parts are formed by sheet metal fabrication processes, from the body shell to the internal bracket structures. The application of sheet metal materials provides strong support for the lightweight and safety of automobiles. In the home appliance industry, the shells, chassis, and other components of various electrical appliances are also largely made of sheet metal. Their good formability and processability can meet the diverse design requirements of home appliance products. In the aerospace field, many structural parts in aircraft components are also made of sheet metal. While ensuring strength, it can effectively reduce the weight of the aircraft and improve flight performance. In addition, products such as metal sinks, electrical enclosures, cabinets, busbars, and mounts are also typical applications of sheet metal fabrication. They, by virtue of the characteristics of sheet metal materials and the advantages of the manufacturing process, play an indispensable role in their respective fields.