Sheet metal is a form of metal produced through industrial processes, typically by rolling or other thinning techniques to create thin, flat pieces. During this process, the metal's thickness is reduced while its surface area generally remains consistent. As a semi-finished product, sheet metal plays a crucial role in sheet metal fabrication and is widely used in modern manufacturing and construction.
Sheet metal fabrication is a precise manufacturing process that involves transforming metal sheets into desired shapes and sizes through various techniques. Numerous products you encounter daily like your stainless steel refrigerator or kitchen sinks are manufactured through this process. So, what exactly is sheet metal fabrication, how does it work, and what about its usages and benefits? In this article, you will find the answers.
What Is Sheet Metal Fabrication?
Sheet metal fabrication is the process of forming metal sheets (usually thinkness less than 10mm) into the desired shape using various manufacturing techniques. Completing a product usually involves several steps, from cutting, forming, to finishing and joining. Each step can be achieved through different fabrication methods. Often, different fabrication techniques can achieve similar end results, but the optimal choice depends on factors such as cost and specific project requirements.
This process is well-suited for producing a wide range of metal components. It supports both high-volume production of standardized products and low-volume manufacturing for custom applications such as prototyping.
How Does Sheet Metal Fabrication Process Work?
Next, we will specifically discuss the process of transforming a simple metal sheet into complex metal parts and explain the most common fabrication techniques involved.
1. Design Stage
The sheet metal fabrication process begins with a flat sheet of metal and a blueprint, usually a CAD file created using Computer-Aided Design software. This blueprint serves as the instructions on how to cut, form, and finish the base material.
Important factors, such as the intended use of the product, the required dimensions and tolerances, and any specific materials or finishes needed, are should determined before manufacturing begins.
2. Cutting
Cutting is typically the first step in fabricating sheet metal. The metal sheets are loaded onto a cutting machine. Next, the machine operates according to the cutting paths derived from the CAD model. Then the sheets are cut into the required shapes and sizes. Cutting operation is divided into two groups: cutting with and without shear forces.
Group One: Cutting Without Shearing
Cutting without shearing refers to cutting methods that do not rely on the traditional shearing action (i.e., using opposing blades or tools to slice through material). Instead, these methods remove material through processes such as melting, vaporizing, or high-pressure abrasive blasting. These methods include the following:
Laser Cutting
Laser cutting is a non-contact process that utilizes a high-powered laser beam focused on the metal sheet. The intense heat from the laser beam melts, burns, or vaporizes the material along the desired cutting path. A jet of gas, usually argon or nitrogen, then blows away the molten or vaporized material, leaving a clean, precise cut.
This method is highly accurate, capable of achieving tolerances within 0.1 mm, and can create intricate shapes and patterns with smooth edges. Additionally, laser cutting is suitable for a wide range of metals, from non-ferrous metals to mild steel and stainless steel, and can be automated for high-volume production.
Plasma Cutting
Plasma cutting uses an extremely high-temperature, high-velocity jet of ionized gas (plasma) to melt through electrically conductive materials. Generated by a plasma torch, the plasma can reach temperatures over 30,000°C, allowing it to melt metal quickly.
This process is particularly fast and well-suited for cutting thick metals. However, compared to laser cutting, plasma cutting tends to create larger burrs and an oxidized zone near the cut area. Despite this, it can still achieve acceptable tolerances for many industrial applications.
Water Jet Cutting
Water jet cutting uses a high-pressure (up to 60,000 psi) and high-velocity stream of water mixed with abrasives to cut sheet metal. As a cold-cutting method, it does not generate heat, reducing the risk of warping or creating heat-affected zones in the material.
Water jet cutting can achieve precise cuts with smooth edges and serves as a good alternative to laser cutting, though it is generally slower. Additionally, laser cutting offers extra capabilities, such as engraving and part marking with depth control, which water jet cutting cannot perform. Water jet cutting also has a larger kerf width of 0.02-0.04” (0.5-1mm), which is significantly wider than that of laser cutting.
Group Two: Cutting With Shearing
Cutting with shear refers to processes of cutting sheet metal by applying a shearing force to overcome the metal’s ultimate shear strength. The techniques included in this category are as follows:
Shearing
Shearing is a cutting process where the action is similar to scissors cutting paper. It involves using two blades — typically a moving upper blade and a stationary lower blade — to apply a shearing force to sheet metal. This force causes the material to deform and fracture along a straight line, effectively cutting it into two or more pieces.
The machinery used for shearing can be powered by hand, hydraulics, electricity, or pneumatics, depending on the material's thickness and the required cut length. Shearing is often employed in high-volume operations, particularly in the initial stages of metal fabrication, to cut large metal sheets down to size before further processing. It is also used to trim sheet edges or to cut out flat parts with straight edges.
Blanking and Punching
In blanking, the metal sheet is placed over a die, and a punch is driven through the sheet, shearing it along the edges of the desired shape. The piece that is cut out, known as the "blank", is the intended part, while the remaining sheet is typically scrap. This process is often used in mass production to create parts that require a consistent, repeatable shape, such as automotive components, coins, and metal tags.
Punching, on the other hand, is the opposite; the material that is punched out is scrap, while the remaining sheet is the desired product. Punching is commonly used to create holes, slots, or specific cut-outs in sheet metal, often for purposes like ventilation openings, fastening, or as part of an assembly process.
Sawing
Sawing cuts through the material by moving a toothed blade back and forth (in a reciprocating motion) or continuously (in a circular motion). The teeth on the blade remove material as they move through it, creating a cut along the desired path. Sawing is used for cutting materials to size, either in preparation for further processing or as a final operation.
3. Forming
The cut pieces of sheet metal are then shaped into the desired form through various sheet metal forming techniques while maintaining their solid state. However, these techniques differ in their applications for creating custom sheet metal fabrications. This section will explain the essential methods for forming sheet metal.
Sheet metal bending is a widely used forming technique that involves using press brakes to fold or bend metal into angular or curved shapes. In this process, the sheet metal is placed onto a die with a specific geometry, such as U-shaped, V-shaped, or channel-shaped dies, and a punch presses the material into the die along a straight axis to form the desired shape. This method is particularly cost-effective for low to medium-scale production.
Rolling
Rolling involves passing sheet metal through one or more pairs of rotating rollers to reduce thickness, ensure uniformity, or impart desired mechanical properties. The rollers can be adjusted to various diameters and angles to achieve the desired shape. This process can be performed at room temperature (cold rolling) or at elevated temperatures (hot rolling), depending on the material and the desired properties of the final product.
Typical products created through rolling include discs, stampings, wheels, tubes, and pipes. Rolling is essential in industries that require mass production of metal components with consistent quality and thickness.
Hemming
Hemming, like the hem on pant legs, is a process in which the edge of sheet metal is folded or rolled over onto itself to form a two-layered edge.The process typically occurs in two stages. In the first stage, the sheet metal is bent to an intermediate angle, often around 90 degrees, using a V-die. It is then removed and placed into a flattening die to complete the hem.
The primary purpose of hemming is to strengthen the edges of sheet metal parts, preventing them from being sharp or prone to deformation. It also enhances the aesthetic quality of the metal, creating a smooth, rounded edge with a clean, finished look, which is important in applications like automotive body panels or appliance covers.
Curling
In curling, the edge of a sheet metal is rolled into a loop or ring shape, creating a rounded, tubular edge. The process first uses a series of rollers or specialized curling dies to gradually form the metal into the desired curved shape. Then, the metal is progressively shaped into a loop, which can be either fully or partially closed, depending on design requirements.
Like hemming, curling is often used to eliminate sharp edges, enhance the visual appeal of the metal part, and increase its structural integrity.
Stamping
Different from previous forming processes, stamping is a technique that integrates both cutting and forming operations to produce complex parts from sheet metal. As a typical cold-forming technique, stamping occurs on a press, utilizing a die and a punch to shape raw materials into various forms. Depending on the type of die used, there are several stamping methods, such as progressive die stamping, deep draw stamping, and fourslide stamping. Stamping is highly efficient, precise, and cost-effective, making it especially suitable for mass production.
4. Joining
If multiple sheet metal parts need to be joined, it can be achieved through the following joining techniques:
Welding
Welding is one of the go-to techniques for joining metal parts. It involves melting the base materials (the metals being joined) and often adding a filler material to form a molten pool, which solidifies into a strong joint as it cools. Shielded Metal Arc Welding (SMAW), Metal Inert Gas (MIG) Welding, and Tungsten Inert Gas (TIG) Welding are different sheet metal welding techniques frequently used.
Fasteners are mechanical devices used to hold two or more parts together. Depending on the type and application, they can be either permanent, like rivets, or removable, such as bolts and screws.
5. Surface Finishing
The final product is given surface finishing operations to enhance the appearance, corrosion resistance, and durability. The types of finishes available for sheet metal are no different from those used for other metal fabrication processes. How suitable a finish is depends heavily on the part’s individual requirements and the properties of the selected material. These finishing operations include bead blasting, polishing, powder coating, anodizing, and plating.
The Materials Used for Sheet Metal Fabrication
The materials used in sheet metal fabrication have mechanical properties similar to their base metals, so the selection of sheet metal materials can be primarily based on the specific requirements of your project.
In addition, since sheet metal fabrication typically involves processes like bending, stamping, or welding, there are a number of factors to pay particular attention to when selecting an appropriate material, like ductility, machinability, weldability, tensile strength, corrosion resistance, etc. A key principle is to choose materials that can be easily manipulated without losing their physical properties. Here are some common examples of such materials.
Aluminum alloys offer high machinability, an excellent strength-to-weight ratio, and corrosion resistance. They are often used in applications where weight reduction is critical, such as in the transportation and aerospace industries. Consumer goods like phones, laptops, and other electronics frequently feature durable and lightweight aluminum casings.
Stainless Steel is an alloy with high tensile strength and resistance to corrosion and high temperatures. It is widely used in applications such as surgical instruments, cutlery, kitchen accessories, and sinks. Stainless steel is also extensively utilized in industrial environments for storage tanks, valves, piping, and other essential components.
Hot Rolled Steel is processed at high temperatures, above its recrystallization point. This makes the steel easier to shape and form, which is why thicker sheets and plates are typically only available as hot rolled—they are easier to produce this way. However, the surface finish of hot rolled steel is usually rougher than that of cold rolled steel, and the dimensional tolerances are less precise. As a result, it is often used in applications where precise shapes and a smooth surface finish are not critical, such as in larger structures like steel sheds and garages.
Cold Rolled Steel is rolled at room temperature, offering increased strength, hardness, smooth surface finish, and tighter tolerances. Ideal for applications requiring precise shapes and smooth surfaces, like home appliances, lockers, and cabinets.
Galvanized steel is steel that has been coated with a layer of zinc to protect it from corrosion. Sheets of galvanized steel are commonly used in outdoor applications or environments where rust resistance is crucial, such as in roofing, fencing, automotive bodies, and HVAC ductwork.
Carbon steel is widely used in both industrial and consumer markets for a variety of products. It is a steel alloy that contains carbon, which increases its hardness and strength when subjected to heat treatment. Known for its durability, high tensile strength, and affordability, but carbon steel is less resistant to corrosion compared to stainless steel.
Copper and brass are widely used in sheet metal fabrication due to their excellent corrosion resistance, conductivity, and workability. Copper, known for its superior electrical and thermal conductivity, is commonly used in electrical wiring, plumbing, and heat exchangers. Brass, an alloy of copper and zinc, combines these properties with enhanced malleability and a distinctive gold-like appearance, ideal for decorative applications, plumbing fixtures, and musical instruments.
Titanium, like aluminum, has a high strength-to-weight ratio, but it also provides exceptional strength and superior corrosion resistance. These attributes make it a go-to choice for extreme environments, including aerospace applications such as aircraft structures and engine components, as well as in military and high-performance automotive industries. Additionally, due to its excellent biocompatibility, titanium finds widespread use in medical devices and implants. However, its hardness and strength also make it more difficult to machine, resulting in increased tool wear and higher production costs.
Benefits and Limitations of Sheet Metal Fabrication
Since sheet metal fabrication encompasses a diverse array of processes and techniques, the advantages and disadvantages can differ significantly depending on the specific method used. The following provides a general overview of the pros and cons of fabricating sheet metal. However, to fully determine if a particular sheet metal fabrication process is suitable for your application, it’s essential to explore each process in greater detail.
Benefits
Prototypes to Volume Production Are Possible
Most sheet metal fabrication techniques are highly automated, which enables the rapid creation of prototypes with exceptional precision and accuracy. For example, laser cutters can achieve cuts with tolerances as tight as 0.0005 inches. This precision and efficiency aren't limited to prototyping; they can be easily scaled for mass production. Processes like stamping, which use molds or dies, allow for the production of thousands or even millions of parts with consistent results.
Vast Options of Techniques And Materials
As discussed in the previous section, various techniques are associated with the sheet metal fabrication process. This flexibility ensures that no matter what your project requires — whether it’s complex shapes, precise cuts, bending parts into place, or adding holes, slots, and notches in exactly the right locations—sheet metal fabrication can meet those needs.
Furthermore, the process allows you to choose from a wide range of sheet metal materials, far beyond the few mentioned in the last part. This extensive variety enables sheet metal fabrication to be applied across numerous industries.
High Strength to Weight Ratio Parts Manufacturing
Sheet metal manufacturing is ideal for producing lightweight yet high-strength components, especially in industries like aerospace and automotive. During the sheet metal fabrication process, operations such as bending and stretching induce work hardening, which increases the material's strength. Additionally, the incorporation of design features like reinforcement ribs, strategic bending angles, and edge curling can significantly enhance the strength and rigidity of the parts without increasing the material thickness.
Limitations
Capability Limits Per Technique
Each technique in sheet metal fabrication has its limitations. For instance, certain materials may deform or crack during welding, and laser cutting may not perform well with highly reflective materials like copper or aluminum. These limitations often necessitate the combination of multiple processes in production. This can involve transferring parts between different machines, with each step requiring reconfiguration, which increases production time. Moreover, the use of multiple machines and additional labor can drive up production costs.
High Initial Cost for Tooling and Equipment
Sheet metal processing requires a series of special equipment, such as laser cutting machines, punching machines, bending machines, and welding equipment. Modern sheet metal processing usually relies on multi-functional CNC equipment, which can improve production efficiency and product quality, but the purchase and maintenance costs are also relatively high.
In addition, for sheet metal processing, particularly in mass production, customized molds such as stamping and bending molds are frequently needed. Designing and manufacturing these molds requires high-precision technology and materials, leading to significant mold costs.
Bending Operations Designs Are Intricate
It may sound simple to bend 2D plates into 3D shapes. But in reality, bending operations require careful consideration of factors such as material properties, bend angles, bend radii, and the sequence of bends. Designing intricate bends involves managing potential issues like springback (where the metal tries to return to its original shape after bending), material thinning, and internal stresses that can lead to cracking or distortion. As designs become more intricate, these factors become more challenging to control, which can limit the feasibility or efficiency of the bending process.
Applications of Sheet Metal Fabrication
Last, let's take an overview of the various industry applications of sheet metal fabrication.
Automotive
Sheet metal fabrication, because of its ability to form large-area parts and its compatibility with a wide range of materials, can create extremely strong frameworks. Body panels, chassis components, door frames, and seat frames are all made from sheet metal that has been cut by laser and punching operations and formed in stamping processes. Additionally, the frame and exhaust systems are roll-formed and then bent into shape using CNC tube benders. Undeniably, sheet metal fabrication is indispensable in automotive manufacturing.
Aerospace
In the aerospace industry, engineers use sheet metal fabrication to create high-precision, lightweight, and high-strength components such as fuselage sections, wing structures, and engine nacelles. These components are made from materials like aluminum, steel, and even titanium and tungsten. Using advanced fabrication techniques, they are formed into large, smooth, and complex shapes that can withstand the stresses of flight while ensuring optimal performance and fuel efficiency.
Construction
Sheet metal fabrication in the construction industry is primarily used for manufacturing structural components, exterior cladding, and functional elements, such as metal roofing panels, corrugated metal siding, and metal 2x4 or 2x6 framing members. These components not only provide excellent protection but are also durable and aesthetically pleasing.
Healthcare
The healthcare industry places a high emphasis on precision and antibacterial properties, making stainless steel the preferred material. Combined with advanced sheet metal fabrication techniques, stainless steel is widely used to produce medical equipment enclosures, surgical instrument trays, medical storage cabinets, and toolboxes.
Enclosures
Sheet metal fabrication helps produce the enclosures of household appliances and electronic products, protecting sensitive gearboxes and equipment. It can also safeguard tools from environmental impacts and prevent dust from entering. Appliances made of aluminum and powder-coated steel are very popular among consumers. By using sheet metal fabrication techniques, you can create various cable connection cuts, such as those for windows, LED panels, light tubes, and HDMI ports.
Conclusion
In this guide, we covered everything you need to get started with sheet metal fabrication — but there’s plenty more to learn. If you’re interested in gaining more in-depth knowledge about sheet metal design, click here for more expert insights.
Chiggo offers comprehensive sheet metal fabrication services to create high-quality metal products while delivering an exceptional customer experience. If you're unsure about which process is best for your project, contact us! We’ll provide the most suitable solution to ensure the quality of your products at a competitive price.
