Sheet metal fabrication is a highly versatile manufacturing process that creates complex parts and structures from metal sheets. From cellphones and kitchenware to submarines and rockets, numerous industries utilise this process to create a wide range of products and technologies that shape our daily lives and facilitate technological advancement. This sheet metal fabrication guide comprehensively explores sheet metal fabrication, exploring everything you need to know about the process.
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Sheet metal fabrication is the process of creating parts, components, assemblies, and structures out of sheet metals, encompassing multiple operations. As the name implies, this manufacturing process is exclusive to metals, with the raw materials being flat metal sheets of various sizes, thicknesses, and metal types, depending on the project and the final product’s application.
In this manufacturing process, flat metal sheets undergo various processing stages to achieve desired sizes, shapes, patterns, and geometries. Sheet metal fabricators cut, form, and assemble pieces of flat metal sheets to create various parts and structures. These include containers, chassis, enclosures, frames, brackets and mounts, barricades, vents, and panels.
Sheet metal fabrication comprises various processes and operations. These processes can be classified into the following manufacturing stages:
- Design
- Fabrication
- Post-processing and finishing
How to 3D print parts. The 3D printing manufacturing steps
While there are many types of 3D printing, They all follow the same broadly defined steps to create a part. The actual printing is just one step, with the complete 3D printing manufacturing process from conceptualisation to the final product involving five steps.
- Creating a 3D digital model of the object
- Slicing the model and converting it to G-code
- Setting up the 3D printer
- 3D Printing the object
- Post-processing and finishing
Design
The sheet metal design stage involves creating 3D models of the structures or parts to be fabricated. In this stage, designers use CAD (Computer-Aided Design) modelling software to create digital replicas of the final product. These may be single models of standalone parts or entire assemblies. Designers meticulously apply dimensions, tolerances, and surface finishes to the model, accounting for part features and position, materials, and potential fabrication processes.
The design stage, creating 3D models, serves two crucial functions. The first is generating machine-readable language, G-code (Geometric code), for CNC (Computer Numerical Control) manufacturing. Modern sheet metal fabrication operations, such as cutting and bending, typically utilise CNC machines. These machines are controlled by embedded computers that dictate various aspects of the operation, enabling highly accurate execution. After designing a model, the designer imports it into CAM (Computer-Aided Manufacturing) software that analyses the model and generates the corresponding G-code, containing specific instructions on producing the part. Operators then program the computer using the G-code.
In addition to facilitating CNC manufacturing, the design stage ensures the feasibility and manufacturability of a sheet metal fabrication project. There are numerous factors that sheet metal fabricators must consider and rules they must follow to fabricate a part successfully. These factors and rules relate to the thickness of the workpiece, type of metal, geometries and shapes, positioning of features, and many more. The sheet metal design stage also guides the fabricators on the appropriate processes and operations required to produce a specific part or structure. See our comprehensive sheet metal design guide to learn everything you need to know about designing for fabrication.
Fabrication
The fabrication stage comprises various operations and processes performed on the workpiece(s) to achieve the final product. These operations include cutting, bending, forming, heat treatment, welding, joining, and assembly. Depending on the project, some of the operations may be optional. There are also various setup stages in which operators prepare the machines for use. Operators may also need to preprocess the material. The various sheet metal fabrication operations are later explored in this sheet metal guide.
Post-processing and finishing
Post-processing in sheet metal fabrication comprises operations carried out after fabrication that enhance the quality of the fabricated part. Post-processing operations may be aesthetic, improving the part’s appearance, or functional, creating desired properties and characteristics. The most common post-processing operations in sheet metal fabrication are heat treatment, such as annealing, tempering, and hardening, and surface finishing, such as coating, anodising, and electroplating.
Sheet metal fabricators produce metal parts and structures from metal sheets using numerous operations and processes. These operations are classified into the following:
- Cutting
- Forming
- Joining and assembly
- Post-processing and finishing
The application of these processes may vary by project. For example, a sheet metal fabrication project may require only cutting and finishing or cutting, assembly, and post-processing. Similarly, while fabricators typically perform these operations in this order, some projects may require forming before cutting or finishing before assembly.
Sheet metal cutting is the process of slicing through the workpiece. This operation has two main functions: cutting away parts of the workpiece to achieve a shape or size and cutting into the workpiece to create a pattern. The cutting technologies predominantly applied in sheet metal fabrication include:
- Waterjet cutting
- Laser cutting
- Plasma cutting
- Mechanical cutting
These cutting methods offer different advantages in terms of accuracy, precision, speed, and cutting abilities.
Waterjet cutting
A highly pressurised water jet cuts through the workpiece during waterjet cutting. The stream of water flows through a tiny nozzle, further increasing its force and stream velocity, with some machines capable of up to 620 Mpa pressure. At these speeds and pressure, the stream acts as a physical blade. The nozzle focuses the jet stream onto the metal workpiece, seamlessly cutting through it on contact.
Waterjet cutting is a CNC process, with computers controlling the movement of the nozzle, the water pressure, and the flow activation. This process may utilise plain water or water containing abrasive particles. Depending on the material, waterjet cutting can cut through various thicknesses of metals up to 300 mm (cutting speed and accuracy start to decrease above 100 mm). One of the advantages of waterjet cutting for sheet metal fabrication is that it is a cold-cutting process. Therefore, it doesn't cause heat-related issues.
Laser cutting
Laser cutting uses a high-energy laser beam generated by exciting lasering materials to cut through metal workpieces. Optics in the machine beam down the laser through a cutting head onto a workpiece below. The laser cuts the workpiece by melting through it. CNC controls the laser's movements and intensity.
Laser cutting can cut through a workpiece or cut out patterns. Depending on the material, this process can cut various thicknesses of metals up to 30 mm.
Plasma cutting
In this sheet metal fabrication process, plasma generated from highly energised gas is the cutting medium. Unlike waterjet and laser cutting, this process is only compatible with conductive materials like metals. This is because plasma cutting is an electrical process. When plasma ejects the nozzle and contacts the workpiece, an electrical arc forms between them, creating enough heat to melt through it.
CNC controls the activation, intensity, and movement of the plasma.
Mechanical cutting
Mechanical cutting describes operations that utilise a physical cutting tool to cut through the workpiece.
- Sawing: This process involves running the sheet metal through a rotating or oscillating saw to cut through it.
- Punching: Punching is the process of perforating the workpiece using shaped cutting tools known as the punch and die. The die is forced into the sheet metal at high speeds, cutting out the specific shape.
- Shearing: In this sheet metal fabrication process, operators feed the sheet metal between two large blades and compress the blades till they cut through the material.
- CNC machining: Mechanical CNC machines can also cut sheet metal. These machines use a rotating cutting tool or a hard metal blade to cut through the workpiece.
Waterjet vs laser vs plasma cutting
Sheet metal forming is the controlled application of force to the workpiece to change its shape or achieve a specific geometry. This crucial sheet metal fabrication process involves forming sheet metal through various techniques to create complex shapes and structures without material removal. Sheet metal forming techniques include bending, stamping, stretching, rolling, and deep drawing.
The processes require different specialised equipment and create varying geometries. Their application depends on the desired shape and structure of the end product. A combination of these processes or multiple executions of a particular process may be required to create a part. Sheet metal fabricators may preheat the workpiece to increase its workability.
Bending
Bending involves folding the workpiece at specific points. The sheet metal workpiece is deformed along a straight axis to form a desired angle or shape. Various bending techniques and machines exist. One of the most common bending techniques is V-bending. In this technique, a punch forces the edge to be bent into a V-shaped die. Other bending techniques include U-bending, Air bending, and Roll bending.
Bending is one of the most predominant sheet metal forming operations and can create circular, cubic, and parametric shapes. This process is also critical in achieving the final geometry and has numerous considerations that vary by material thickness, bend orientation and angle, and intended shape.
Stamping
Sheet metal stamping is the process of pressing a shape into a workpiece or vice versa. In this process, sheet metal fabricators place a blank, flat workpiece in a stamping press. The press contains a die with the desired shape. When the stamping force is applied, the metal is deformed into the shape of the die.
Rolling
Rolling is a sheet metal fabrication operation that involves passing the workpiece through a set of rollers. The rollers compress the workpiece as it passes through, reducing its thickness. Fabricators use this operation to achieve uniform thickness or to make the workpiece thinner. Certain applications require passing the workpiece through different rolling machines with progressively lower distances between the individual rollers to create lower thicknesses. Rolling produces flat, straight geometries. It can also be used to create curves.
Deep drawing
In deep drawing, a punch forces a blank sheet metal into a specifically shaped hollow die. The punch and die are shaped in a way that they fit. For example, if the die is a cylindrical hole, the punch will be cylindrical with a diameter close to the die's but with clearance. The blank is placed in between the punch and die. When the force is applied, the punch stretches and draws the workpiece into the hollow die, and the workpiece takes the shape of the die. Sheet metal fabricators use drawing to create hollow container-like parts that are round or have rounded edges.
Spinning
In sheet metal spinning, operators clamp a flat metal disc or tube onto a lathe-mounted rotating mandrel. As the mandrel and workpiece rotate at high speeds, a forming tool progressively presses the workpiece against the mandrel at specific points, gradually forming it into an axially symmetrical shape. Sheet metal spinning forms cylindrical, conical, and other round geometries.
Joining and assembly encompasses techniques, operations, and processes used to assemble processed workpieces to form a final sheet metal part or structure. Typical sheet metal joining operations and techniques include.
- Welding
- Brazing and Soldering
- Fastening
- Adhesive bonding
Sheet lamination is compatible with thermoplastics, sheet metals, paper, glass, and composites such as carbon fibre and Kevlar.
Welding
Welding is the process of joining metal parts by melting the joint edges and allowing them to fuse on cooling. In this sheet metal fabrication process, operators position the parts with the weld edges in contact. The operator uses a high-energy thermal source to raise the temperature at the edges to their melting point, adding a filler material to the molten weld pool. Upon cooling, the edges solidify, creating a solid permanent joint.
Pros:
- Creates strong, permanent joints with similar strengths to the base metal
- Compatible with a range of ferrous and non-ferrous metals
- Makes it possible to create complex structures as a single unit without any visible or movable joints.
Cons:
- The heat-induced expansion and contraction of the workpiece may create residual stresses in the part.
- Requires skilled operators
Various types of welding techniques exist. These techniques vary by the energy source and consumables used. The most common in sheet metal fabrication are TIG (Tungsten Inert Gas) welding and MIG (Metal Inert Gas) welding.
Also known as Gas Tungsten Arc Welding, TIG welding uses a non-consumable tungsten electrode to produce the weld. An inert gas, typically argon, shields the weld area from contamination. TIG welding is known for its precision and is often used for welding thin materials and applications requiring high-quality welds.
On the other hand, MIG, also known as Gas metal arc welding, utilises a continuous wire electrode fed through a welding gun. It typically uses a mix of argon and carbon dioxide as shielding gas to protect the weld area from contamination. MIG welding is known for its speed, ease of use, and ability to weld thick cross-sections of steel and ferrous alloys.
Brazing and soldering
Brazing involves using a filler metal to bond workpieces together without melting the base metals. In this process, the operators place the workpieces together. They then melt a filler metal, with a lower melting point than the base metals, over the joint. The molten filler metal flows into the gaps of the workpieces’ joints and bonds them together upon cooling.
Soldering follows the same principles as brazing, with the difference being the temperatures at which they occur. Brazing is done at temperatures above 450⁰C. While soldering is performed below 200⁰C. Both processes must be below the temperature of the base metals.
Pros:
- It can bond different types of metals together.
- The lower temperatures reduce the risk of heat-related issues in the workpiece.
- Creates leakproof bonds, as the filler metal completely seals the joints
Cons:
- Creates weaker bonds than welding. This is a result of the difference between the internal structures of the filler metal and the base metal
- Better suited to thin, small workpieces
Fastening
Fastening involves using hardware fixtures to hold sheet metal parts together mechanically. These fixtures may be incorporated into the workpiece or be external.
Threaded holes and screws: Operators create threaded holes by tapping pre-drilled holes in the workpieces. They then join parts by aligning the holes and screwing them together using screws. Other threading methods include the use of threaded inserts.
Bolts and nuts: In this method, operators drill non-threaded holes through the workpieces at the points where they are to join. To fasten them, the operator aligns the holes, passes a threaded bolt through and attaches the nut on the other side.
Rivets: The riveting process is very similar to using bolts and nuts. However, it uses non-threaded cylindrical pins with wider heads known as rivets instead. The rivet is inserted through the holes and extends out of the other end. An operator uses a hammer to flatten the other end of the rivet to be wider than the hole, securing it in place.
Pros:
- Requires less effort, time, and cost than welding and brazing
- Parts can be easily disassembled for transportation and storage
- Does not cause heat-related issues in the final product
- Facilitates the joining of metals with other materials.
Cons:
- Joints are not as strong as in welding
- Typically limited to overlapping joints
Adhesive bonding
Adhesive bonding is the use of industrial-grade adhesives to join parts together. This sheet metal assembly technique can join sheet metal with other materials such as wood and plastic
Pros:
- Simple, straightforward process
- Can join different types of materials
- Does not affect the physical properties of the parts
Cons:
- Creates relatively weaker joints
- Disassembly may require destructive processes
Sheet metal fabricators need to follow specific guidelines to ensure seamless fabrication. Designers apply most of these guidelines during the design stage, while the fabricators execute them during production. The guidelines cover various aspects of cutting, forming, and bending, including rules on dimensions, tolerance, how to create various features, feature placement, material considerations, and efficiently performing processes.
- Account for every process involved in fabricating a part, including order, accessibility, and the effect of the processes on the workpiece.
- When cutting out a shape from a larger piece of sheet metal, optimise the layout to minimise waste.
- Include relief cuts at the ends of cut lines to prevent material tearing or warping during cutting and forming.
- Account for kerf width when assigning dimensions to parts. Kerf is the width of material that is removed by a cutting process. For example, laser cutting cuts by melting away 0.1 mm to 0.3 mm of material
- Design walls with uniform thickness to ensure even distribution of forming stresses and to prevent thinning.
- Consult relevant charts, such as K-factor charts and bending charts, to obtain the right values for your project’s specific material and thickness.
- Position features in ways that they wouldn't be affected by subsequent processing. For example, holes should be designed away from bends as they may distort during bending.
- Metals tend to slightly return to their original shape after bending. This phenomenon is called springback. To account for spring back, slightly extend bend angles beyond the desired value.
- Design for the specific joining methods by accounting for accessibility, joining features, and the effect of the joining process on the part. For example, design overlapping holes for parts to be assembled via screws.
- Include features that facilitate the real-life application of the finished product. For example, incorporate ribs and gussets into load-bearing parts.
There are numerous other rules and guidelines involved in sheet metal fabrication. Many of which relate to specific features and fabrication processes. See our comprehensive sheet metal design guide for everything you need to know about designing sheet metal parts.
Sheet metal Post-processing and finishing
Post-processing refers to operations performed on a fabricated structure or part to bring it to a desired physical state or induce certain characteristics. It improves the overall quality of the finished product and may be functional or aesthetic. Sheet metal post-processing operations can be classified under heat treatment and finishing.
Heat treatment is the controlled heating and cooling of the part or structure. Sheet metal fabricators use heat treatment to receive stresses that form during fabrication and elicit desired properties. These operations always come before finishing operations. Common heat treatment operations are:
- Annealing
- Tempering
- Normalising
- Through hardening (Quenching)
- Case hardening (Carburising)
Finishing typically describes post-processing operations directed at the surface of the part. These operations alter colour, surface finish, and surface properties. Operators perform finishing operations to improve aesthetics, provide protective coatings, and induce certain properties. Common sheet metal finishing operations include:
- Bead blasting
- Powder coating
- Anodising
- Electroplating
- Chemical coating
Note that while post-processing operations are typically performed after assembly, some projects may require some of the operations before assembly. For example, a sheet metal fabricator is likely to powder coat a part before assembling it with screws.
Bead blasting
Bead blasting involves spraying a continuous, pressurised stream of tiny abrasive glass or plastic beads at the part's surface. This stream knocks off loose particles, removes burrs and imperfections, and smoothes out the surface, leaving a uniform satin or matte surface. Sheet metal fabricators predominantly use bead blasting for aesthetic finishing and as a preliminary surface preparation process for other finishing operations. Bead blasting is compatible with small to large-sized parts.
Tumbling
In the tumbling process, the part is placed in a vat of vibrating granular tumbling media over a specific period. The media progressively knocks off impurities and smoothes the part as the vat vibrates. Tumbling is limited to small to medium-sized parts, depending on the size of the vat.
Powder coating
Powder coating involves applying a thin layer of electrostatic, coloured polymer powder to the part’s surface, followed by curing. This process creates a smooth, coloured, visually appealing protective layer on the part, thus improving aesthetics and providing corrosion and weather resistance.
Powder coating is a more durable option than painting and is compatible with all metals. However, it cannot be easily applied to internal surfaces.
Anodising
Anodising is an electrochemical process that creates a layer of stable oxide coating on a part or structure. In this process, the part is submerged as an anode in a bath of acid (typically sulphuric or chronic), and an electric current is applied, causing the formation of a metal oxide layer. Anodising creates a smooth, highly resistant, visually appealing surface.
There are three main types of anodising, with the difference between them being the type and temperature of acid used and the duration of the process. These methods form layers with different characteristics. The types are Type I (Chromic acid), Type II (sulphuric acid), and Type III (sulphuric acid at a lower temperature and higher voltage).
Type II produces a layer thickness of 0. mm to 0. mm, while Type III produces a thickness of 0.025 mm to 0.05 mm. The Type II coating is also very receptive to dyes, providing numerous colour options. Anodising is typically used with aluminium but is also compatible with titanium, zinc, and magnesium.
Electroplating
Electroplating is an electrochemical process that deposits a thin layer of another metal on the surface of the sheet metal fabricated part. Common metals used in electroplating include gold, silver, and copper. In electroplating, The finished part is immersed in a solution containing plating metal ions. An electric current is applied, causing the ions to deposit onto the part's surface.
Electroplating improves corrosion resistance, improves surface finish, and creates a visually appealing surface. This process makes it possible to create a part with the properties of a particular metal without having to fabricate the entire part from the metal. For example, rather than creating a costly pure solid gold part, a sheet metal fabricator can create a part from steel and electroplate it with 70 to 90% less gold.
Annealing
Annealing is the process of heating the part or workpiece to a specific temperature, followed by slow, controlled cooling. This process relieves internal stresses, improves ductility, and reduces hardness.
Normalising
Normalising is similar to annealing but utilises air cooling at room temperature rather than the slow, controlled cooling utilised in annealing. This air cooling results in a more uniform grain structure and improved mechanical properties.
Through Hardening
Also known as quenching, this process involves heating the workpiece to a high temperature and rapidly cooling it via immersion in a quenching medium such as oil, water, or air. As the name implies, hardening increases the workpiece's hardness and resistance to wear, abrasion, and deformation.
Tempering
Tempering is typically performed after hardening to increase the toughness and reduce the brittleness of hardened parts. It involves reheating the workpiece to a specific temperature, holding that temperature, and then allowing it to cool on its own. The temperature determines how much of the hardness is reduced. Tempering creates a balance between hardness and toughness.
Quality control inspection is a critical aspect of sheet metal fabrication that ensures that the final products meet the required standards and specifications. Effective quality inspection involves three main stages: visual inspection, dimensional inspection, and nondestructive testing.
Visual Inspection
Visual inspection is the first line of defence in quality control. It involves thoroughly examining the sheet metal parts to identify any visible defects, such as surface imperfections, scratches, dents, or discolouration. Inspectors typically use magnifying glasses, mirrors, and machine learning cameras to aid in detecting defects, ensuring that each part meets visual quality standards before proceeding to further processing.
Dimensional Inspection
Dimensional inspection ensures that the fabricated parts meet the specified dimensions and tolerances. Inspectors use tools like callipers, micrometres, and high-precision lasers to measure the thickness, width, length, and numerous other dimensions of the sheet metal components. These precise measurements help identify any deviations from the design specifications, allowing for corrective actions to be taken before further processing.
Non-Destructive Testing
Non-destructive testing (NDT) is crucial for detecting internal defects without damaging the parts. Ultrasonic and radiographic testing are two common testing methods.
- Ultrasonic Testing uses high-frequency sound waves to identify flaws such as cracks, voids, and inclusions within the metal. The sound waves are transmitted through the material, and the reflected waves are analysed to detect irregularities. Ultrasonic testing is particularly useful for detecting defects in thick or complex parts that cannot be visually inspected.
- Radiographic Testing employs X-rays or gamma rays to create images of the internal structure of the components. It effectively identifies internal defects like porosity, inclusions, and cracks. The resulting radiographs provide a detailed view of the metal's internal condition, ensuring its reliability and safety. This method is often used in critical applications such as the aerospace and automotive industries, where material integrity is paramount.
Both ultrasonic and radiographic testing provide valuable information about the integrity of the sheet metal parts, ensuring their reliability and safety. These methods help manufacturers maintain high-quality standards and prevent the use of defective materials in final products.
Geomiq provides industry-leading post-production quality inspection involving these and more procedures. Every single order is subjected to thorough standard inspection for the utmost quality. You can also request advanced or custom inspection. Our numerous ISO certifications, including ISO : and ISO :, testify to our absolute commitment to superior quality standards. Visit our quality assurance page to learn more about Geomiq’s quality guarantee.
Sheet metal fabrication is compatible with various metals and their alloys. These materials are selected for different applications based on their properties, availability, and cost. The table below lists common sheet metals and their properties, common applications, and relative cost. Note that the table contains common sheet metals and is not exhaustive. In addition, each of the metals listed has alloys with varying properties.
Common sheet metals and their properties, applications, and relative cost
Geomiq offers these and more sheet metal material options. See our materials page to learn more. Not sure about the right material for your application? Contact us to discuss your project with our team of engineering professionals and select the best material for your application.
The applications of sheet metal fabrication are almost endless. This highly versatile manufacturing process is used in numerous industries to produce a wide range of products. Research and Markets estimates that the global Sheet Metal Fabrication Services market will surpass £15 billion by . From providing shipping containers that support global trade to building vehicles for outer space exploration, sheet metal fabrication is practically indispensable to civilisation.
Aerospace
Sheet metal fabrication is indispensable in the aerospace industry and is widely employed in aircraft and outer space applications. Numerous aerospace components and machines are manufactured from sheet metals. These include aircraft bodies, fuselages, skins, engine components, and spacecraft. A characteristic of sheet metal fabrication that is especially beneficial to the aerospace industry is its compatibility with various metals. This characteristic makes it possible to meet the various high demands of the industry. For example, sheet metal fabrication is compatible with aluminium for strong, lightweight aircraft parts and titanium to withstand the heat of spacecraft takeoff and the frigid temperatures of space. SpaceX’s Falcon 9 rocket is manufactured using sheet metal fabrication techniques from various aluminium and lithium alloys.
Automobile and transportation
Sheet metal fabrication is the predominant manufacturing process in the automobile industry. Over 50% of car parts and components are manufactured from sheet metal, using a variety of sheet metal fabrication processes. Automobile parts such as body panels, quarter panels, floor pans, frame rails, inner fenders, brackets, mounting plates, bumpers, fluid tanks, casings, and more are all manufactured via sheet metal fabrication techniques, including cutting, stamping, rolling, drawing, welding, and numerous others.
This manufacturing process is fast, highly scalable, precise, and compatible with various metals, making it perfect for the automobile industry. Sheet metal fabrication extends beyond automobiles to other automotive and locomotive vehicles. Buses, lorries, trailers, rail cars, trains, and even tractors all predominantly feature sheet metal parts. In addition, maritime transportation is also facilitated via sheet metal fabrication. Marine vehicles, such as ships, submarines, and deep-sea trawlers, are all made from sheet metals.
Construction, building and architecture
The application of sheet metal fabrication in the construction industry is as vast and varying as the industry itself. Sheet metal is applied in building cladding, roofing sheets, doors and windows, plumbing and waste management, HVAC, power and gas supply, finishing, facades, railing, structural elements, gates, and decorative elements. Sheet metal fabrication’s vast construction applications are due to the durability, strength, high weather resistance, manufacturability, versatility, aesthetic qualities, and other beneficial properties of various sheet metals, including steel, aluminium, and copper.
One of countless examples of sheet metal fabrication in the construction industry is the Walt Disney concert hall in Los Angeles, USA. This building features an iconic stainless exterior comprising curves and complex shapes that the builders created using advanced sheet metal fabrication techniques.
Industrial machinery and equipment
This sheet metal application cuts across various industries. Many of the equipment and machinery used in production, agriculture, manufacturing, and oil and gas industries have sheet metal components, brackets, enclosures, and frames.
Packaging, storage, and transportation
Sheet metal was one of the earliest forms of packaging and continues to be the go-to packaging material for numerous products. Sheet metal fabrication produces small to medium-sized containers for canned foods, beverages, paint, aerosols, gases, oils, and chemicals.
Manufacturers also produce large industrial-sized containers for storing various solids, liquids, and gases from sheet metal. This application cuts across various industries, including agriculture (silos), oil and gas (fuel storage tanks), shipping and logistics (Maritime containers), food and beverage production (production tanks), chemical processing (mixing and storage tanks), and many more.
Consumer goods
Various Manufacturers utilise sheet metal fabrication to produce numerous consumer items. These items include the following:
- Electronics: Phones, tablets, TVs
- Electrical appliances: Electric irons, electric kettles, microwaves
- Kitchenware: Cookware, utensils, countertops, sinks
- Bathroom fixtures: Sinks, shelves, plumbing
- Musical instruments
- Garbage bins
- Sports goods
- Furniture
- Personalised items
Defence
The versatility of sheet metal fabrication makes it indispensable in the defence industry. This manufacturing method provides various metal options with the unique properties often required in defence applications. Examples include tungsten alloys for armoured tanks, copper and brass for ammunition, carbon steel for weapons, and titanium for military satellites.
Capability: Sheet metal fabrication can produce numerous complex cubic and parametric geometries, as well as various curves, shapes, and patterns. In addition, sheet metal manufacturers can use sheet metal fabrication techniques to produce extremely high-quality, durable parts and structures.
Versatility and availability of options: Sheet metal fabrication has various capabilities and characteristics that make it a highly versatile manufacturing process. This process can create standalone parts or whole assemblies, small or large structures, and one-off or large-scale productions. It is also compatible with numerous metals.
Another characteristic that adds to sheet metal fabrication’s versatility is the availability of processing options. At every stage of processing, there are several options to choose from, depending on the project. For example, cutting options include waterjet, plasma, and laser cutting. There are also various forming options, such as drawing, bending, spinning, etc. In addition, sheet metal fabrication is compatible with numerous finishing options.
Scalability: Most sheet metal fabrication processes can either be automated or process multiple parts simultaneously. This characteristic makes fabrication highly scalable and suitable for large production volumes. Most applications of sheet metal fabrication are carried out on an industrial scale using automated production lines.
Materials: Sheet metal fabrication is compatible with hundreds of pure metals, alloys, and super alloys. There are suitable sheet metals with unique properties for almost every possible application.
Accuracy: Incorporating advanced CNC machinery significantly increases the accuracy and precision of sheet metal fabrication processes. Computers can control various aspects of fabrication, including cutting, forming, and bending. CAD also provides manufacturers with the ability to account for potential errors right from the design stage
Requires skills: Sheet metal fabrication requires highly skilled personnel from design to finishing. Most steps require meticulous execution. Fabricators must also follow numerous rules to ensure manufacturability, mitigate challenges during manufacturing, and achieve high-quality finished products. In addition, certain metal fabrication processes, such as welding and powder coating, are manual, increasing the possibility of error and the need for highly skilled workers.
Involves multiple operations: Unlike CNC machining and 3D printing, which typically involve one or two processes, most sheet metal fabrication projects require multiple processes. This significantly increases the fabrication time for one-off and manual productions.
Affects material properties: The deformation and temperature changes that workpieces undergo during fabrication may affect the internal structures of the metal. These changes can lead to stresses in the material and negatively impact its properties.
Generates waste: The sheet metal cutting process typically generates scrap from the trimmings and cutouts. However, this issue is mitigated by the fact that most sheet metal is recyclable.
Conclusion
The Basics
What is sheet metal fabrication?
Sheet metal fabrication is the process of bending, cutting, and/or punching sheet metal to form into a functional part. The basic process can be simplified into three main steps. First, a 3D model of the design is created using CAD software. Then the CAD file is converted into machine code and the machine is set up. Finally, the machine precisely forms the sheet metal into the desired shape using one or a combination of the processes mentioned above.
Parts are manufactured from a single piece of sheet metal so designs should have a uniform thickness to them. Sheet metal comes in a range of thicknesses from 0.5 mm - 6 mm, anything thicker than this is considered metal plate, thicknesses up to 20 mm can be manufactured. Parts manufactured using sheet metal fabrication are known for their durability and can scale from one-off prototypes to high-volume production.
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What are the different types of sheet metal fabrication?
Laser Cutting
One of the key methods for cutting sheet metal is using a laser cutter. Laser cutting uses a high energy beam that is intensified with a lens or mirror to burn/vaporise the material to form a cut. It is a very quick and precise method for cutting sheet metal and has a reduced chance of warping due to the small heat-affected zone. C02 and fibre lasers are most commonly used and can cut material up to 10 mm thick.
Water Jet Cutting
Another sheet metal cutting method is water jet cutting. Water jet cutting uses an extremely high-pressure jet of water (which can also be mixed with an abrasive substance) to form the cut in the material. It is a preferred fabrication method over laser cutting when cutting materials with a low melting point such as plastics and aluminium to prevent unwanted deformation.
US Metal Spinning supply professional and honest service.
Plasma Cutting
The third and most powerful sheet metal cutting method is plasma cutting. Plasma cutting works by creating an electrical channel of extremely hot, electrically ionised gas (plasma) which melts the material to form the cut. It is an effective method for cutting material over 10 mm thick, however, the precision of the cut is not to the same level as laser or water jet cutting.
Guillotining
Sheet metal guillotines are an effective method for creating clean, accurate cuts in sheet metal. The sheet is fed between two blades which are then compressed together at a high force to deform the sheet until it eventually produces the cut. Guillotining is a quick and inexpensive method for producing high-quality cuts, although it can leave the metal with a slightly deformed edge.
Punching
Sheet metal punching uses a similar cutting mechanism to guillotining however, it uses a shaped metal tool (known as a die) to make the cut. The die is forced into the sheet metal at a high speed to perforate the sheet. Dies of standard shapes (circle, square, rectangle) are commonly used however, custom tooling can be made for punching more complex shapes. This method is better suited for high volume production due to the cost of manufacturing the die.
Bending
Bending is a fundamental manufacturing process to form sheet metal into functional parts. Sheet metal is bent using a machine known as a press brake comprised of an upper tool (punch) and a lower tool (V-die). Material is placed between the tools and the punch presses down into the V-die to form the bend. The bend angle is determined by the depth the punch is pressed downwards into the V-die.
Assembling
Cutting and bending are two ways of forming sheet metal, assembly is the third way. Assembling sheet metal components can be achieved using mechanical fasteners such as bolts, screws and rivets. Or they can be joined using the process of welding, where two or more parts are fused together using intense heat and then allowed to cool to form a join.
Advantages of CNC Sheet Metal Fabrication
✅ Cost-effective
Sheet metal fabrication is a fast and cost-effective solution for manufacturing a one-off prototype design up to a high volume production run of thousands of parts. With the ability to automate a lot of the process the manufacturing process can efficiently scale to very high volume production.
✅ Material Selection
A broad range of materials can be used for sheet metal fabrication. Sheet metal can be made from a variety of materials that each have their own individual characteristics and offer unique characteristics.
✅ Lightweight
A lot of materials that are known for their durability come with a weight penalty. Metal sheets are lightweight so sheet metal fabrication can offer the durability of a material with the combination of being lightweight and highly portable.
Disadvantages of CNC Sheet Metal Fabrication
❌ Complex Designs
Sheet metal fabrication is a very flexible manufacturing process however, some materials are not malleable enough to be formed into highly complicated shapes or designs. So there are some design limitations on what materials and thickness of material can be used when designing complex components.
❌ Fixed Uniform Thickness
Parts are formed from a single piece of sheet metal which restricts the design to a uniform thickness throughout.
Sheet Metal Design Guidelines
Bending
As mentioned earlier sheet metal is bent using a machine known as a press brake comprised of an upper tool (punch) and a lower tool (V-die). Material is placed between the tools and the punch presses down into the V-die to form the bend.
Bend relief
When a bend is made close to the edge of the sheet it runs the risk of tearing. To eliminate this a relief should be added to help control the sheet metal material behaviour and prevent unwanted deformation during bending operations. The relief cut should be rectangular with a depth more than the bend radius and width greater than the material thickness. A corner relief notch should be added if two bends extend all the way to the edge of the part. Various cutouts shapes can be used to create the relief but the depth should be no deeper than the material thickness plus bend radius.
Bend height
To ensure a high-quality bend the height of the bend should be at least 2x the thickness of the material plus the bend radius. If the height is too small the sheet metal will not deform correctly when bending.
Bending next to holes
If a hole is placed too close to a bend line it can be pulled out of shape by the action of the bend that is too near to it. Sometimes this is not an issue if it is simply a clearance hole for a screw or bolt however, for holes that are to be threaded this will cause tapping issues.
There are two formulas that can be used to ensure the holes in your design do not fall into the bending deformation zone when close to a bend. If the hole has a diameter less than 25 mm, the hole should be placed at a distance 2x the thickness of the material plus the bend radius from the outside edge of the bend (d = 2t + r). If the hole diameter is greater than 25 mm, the hole should be placed at a distance 2.5x the thickness of the material plus the bend radius from the outside edge of the bend (d = 2.5t + r). If the holes need to be placed close to a bend they should be drilled out after the bending operation. This will increase part cost due to the additional machining time.
Laser cutting
There are a few things to be aware of when using laser cutting to process your parts. First, the high-intensity laser creates extreme heat in the part in order to create the cut. This creates a heat-affected zone (HAZ) along the edge of the cut. For most parts, this change in the microstructure is not an issue but for critical parts, this should be considered as the HAZ causes a reduction in material strength.
The second thing to consider is that the cut line will have a taper to some degree due to the shape of the laser. The laser cannot be focused perfectly straight through the focusing lens and as a result, the laser creates an hourglass-shaped cut. This is only noticeable on parts thicker than 1.5 mm so only needs to be considered when working with thicker sheets.
The third thing to consider is the laser burns away a portion of the material when it cuts through. This is known as laser kerf and can range from 0.05 mm - 1 mm depending on the material type and other conditional factors. Most modern CNC machines automatically adjust to take into account this offset to ensure the final dimension of the part is correct.
Curls
Curling sheet metal is the process of forming the edge of the sheet into a hollow ring. This method is commonly used to remove sharp edges from the workpiece so that is safe to handle.
When adding curls to your design, the outer edge radius of the curl must be greater or equal to 2x the material thickness. If you need to add holes near to a curl feature in your sheet metal, ensure they are positioned at a distance greater than the curl radius plus the material thickness. A bend feature should be located no less than the distance of the curl radius plus 5x the material thickness from a curl feature.
Countersink holes
Countersink holes are conical shaped holes and are added to parts to allow the head of a countersunk bolt/screw to sit flush with the surface of the sheet metal.
Countersinks should be a distance of 8x the material thickness from another countersink, 4x the material thickness from the material edge and 3x the material thickness from a bend.
Hems and seams
Hemming and seaming are two similar fabrication methods where the edge of the sheet is rolled/folded over on itself. Hemming is the process where the edge is folded back on itself to sit flush, while a seam joins the edges of the two materials. Hems are commonly used to remove sharp edges so they are safe to handle, improve the appearance and reinforce the edges. Seams are used to join two pieces of sheet metal together. For example, the join between the lid and the can on a baked bean tin is a seam.
The inside diameter of an open hem should be no less than the thickness of the material, and the folded sheet should return back against the sheet at least 4x the thickness of the material. For a flattened hem, the folded sheet should return at least 8x the thickness of the material. A teardrop hem is used when the material does not have the ductility required to form a flattened hem. The same design rules apply to a teardrop hem as they do to an open hem.
Holes and slots
When adding holes in sheet metal it is recommended to keep the diameter of the hole larger than the thickness of the sheet metal so punching equipment can be used. If a smaller hole is required punching cannot be used at the tool may break so a laser cutter needs to be used. Holes can tear if they are placed too close to a bend.
The minimum distance a hole should be from a bend is, 2x the material thickness plus the bend radius. Slots are even more prone to deforming so they should be placed at a distance of 4x the material thickness plus the bend radius from the bend. It is also important to consider how close a hole or slot can be placed to the edge of the material to avoid tearing. It is advised to place holes and slots at least 2x the material thickness from the edge. Ideally, the distance between holes should be kept at a distance of 5x the thickness of the material.
Notches and tabs
Notches are added to sheet metal by either a shearing or punching process. Usually, this method is a precursor to a forming process such as bending but they are also sometimes the sole purpose.
The minimum width of a notch should be at least the material thickness and the depth no greater than 5x the width. For bends, notches should have a width of 3x the material thickness plus the bend radius and a depth no greater than 5x the width. The width of tabs should be at least 2x the material thickness or no lower than 3 mm.
Fillets
Much like curling, fillets can be added to sheet metal to remove sharp edges, making parts safer and easier to handle. It is recommended to add a fillet with a radius equal to or greater than 0.5x the material thickness.
Wall thickness
It is important that parts maintain a uniform thickness throughout. Get It Made has the capabilities to manufacture sheet metal from 0.5 mm - 20 mm.
Sheet Metal Materials
A broad range of metals can be used for sheet metal fabrication and the selection should depend on the mechanical properties, thickness and desired form. The most common metals will be outlined below with their unique properties and benefits.
Hot Rolled Steel (HRS)
Hot rolled steel is steel that has been roll-pressed at very high temperatures, over 900°C, which is above the re-crystallisation temperature. The result is a steel that is much easier to form and therefore easier to work with but it is harder to keep to tight tolerances.
✅ Good formability making it suitable for a variety of shapes and forms
✅ Suitable for high volume productions
✅ Lower cost than cold rolled steel
❌ Lower achievable tolerances compared to cold rolled steel
❌ Rougher surface compared to cold rolled steel
Cold Rolled Steel (CRS)
Cold rolled steel goes through the same high temperature rolling process as HRS however, an additional room temperature rolling process is performed on the steel. The result is a steel with closer tolerances and an increase in material strength by up to 20%.
✅ Increased strength and hardness compared to HRS
✅ Tighter tolerances make true edges and square corners achievable
✅ Less spring back when forming
❌ Increased cost compared to HRS
❌ Requires additional finishing to prevent corrosion
Aluminium
Aluminium is easily alloyed with additional materials such as copper, magnesium and silicon meaning it comes in lots of different grades making it suitable for a variety of applications. Al is pure aluminium with very high electrical conductivity, formability and corrosion resistance but comes at the cost of lower mechanical strength. Al has the highest mechanical strength out of the non-heat-treated alloys combined with great fatigue resistance. However, the main advantage of this alloy is its ability to be formed into complex shapes.
✅ Corrosion resistant
✅ Weighs ~1/3 of other materials like steel
✅ Great formability, workability and weldability.
❌ Increased cost over steel
❌ Lower mechanical strength compared to steel
Stainless Steel
There is a range of stainless steels grades that can be used for sheet metal fabrication, all of them having a chromium content of over 10.5% making them corrosion resistant. The 300 series sheets of steel are the most commonly used as they do not require heat during the fabrication process. SS304 is ~25% cheaper than SS316 but doesn't have as good mechanical strength or resistance to corrosion in saltwater.
✅ Presence of chromium creates corrosion resistance
✅ Suitable for a wide variety of additional manufacturing processes
✅ Excellent combination of strength and hardness
❌ More expensive than aluminium and steel
❌ Corrosion can occur at thick weld points
Cold Galvanised Steel
Cold galvanised steel is steel that has had a protective zinc coating applied to its surface by brushes, sprayers or electro galvanising. The paint includes binders that cause it to mechanically bond to the steel.
✅ Provides protection against corrosive environments
✅ Cost effective way to protect steel
✅ Low maintenance and increases the life expectancy of parts
❌ Extra cleaning step required before coating
❌ Doesn't offer as good protection as hot galvanised steel
Cost Reduction Tips
This section will outline some simple adjustments you can make to your designs to help reduce the overall part cost. There are three main areas that will significantly affect the cost of your part:
- Design - Complex parts result in increased manufacturing time.
- Material - The cost of the bulk material and how easily it can be machined.
- Quantity - Cost per unit reduces with an increase in quantity due to fixed setup costs.
Design
Use simple bends
As a general rule of thumb, the more complicated your part is the more expensive it will be to manufacture. Therefore, when designing your parts try to keep the bends as simple as possible. Small bends relative to the material thickness are often inaccurate and difficult/expensive to produce.
Only apply tight tolerances to critical components
To manufacture holes, walls and threads to tight tolerances is an expensive process as it increases the overall manufacturing time for each part. Post-machining inspection using a micrometre or CMM tool is also required, further adding to the cost. It is therefore advised to only add tolerance call-outs to critical features in your design.
Design to a standard sheet gauge
Ensure your part is designed around a standard sheet metal gauge to prevent the need for additional machining. Thicker sheets may restrict your achievable design capabilities, so ensure the common gauge you select is suitable for all your bends and design features.
Keep the bend line consistent
When you have multiple flanges along the same edge it is advised to bend them all along the same bend line. If each flange is bent along a separate bend line the machine technician will have to reposition the part multiple times, increasing machining time and cost.
Use standard holes
Standard holes sizes can be drilled quickly and accurately with drill bits. However, if you require a non-standardised hole CNC machining will need to be used, increasing the cost. It is also important to keep holes a suitable distance away from the edge of the part to avoid creating a problematic thin wall feature.
Material
Two factors affect the cost of certain materials for sheet metal fabrication, the raw material cost and the machinability. Raw material costs do fluctuate over time however we keep our material prices consistent so part costs remain fixed for repeated orders. Machinability refers to how easily the material can be machined. The better the machinability of material the quicker the machining time, resulting in reduced cost. Yet the main cost of using a certain material is the bulk material price.
It is advised to select the lowest cost material that has the properties which meet your design requirements. If you are unsure about what material to select, submit a quote with us for a range of different materials to give you an idea of the price range.
Quantity
Without any design changes, the cost of your part can be reduced significantly by just increasing the order size. Our engineers have to perform the part setup, programming and tool choice which is a fixed cost. By manufacturing multiple parts at the same time the fixed cost can be shared, making each individual part more economical.
Getting Your Part Made
1) Design and export your CAD file
Use the Sheet Metal Design Guidelines to help design your parts ready for machining. Then please export your 3D CAD files to STEP, IGS or PARASOLID format. Unfortunately, we can only accept STL files for 3D printing projects. We cannot accept OBJ files as they do not correct geometric data for manufacturing.
2) Create an engineering drawing
We highly recommend sending supporting PDF engineering drawings for each part. This is required when a part has: thread holes, critical dimensions, tolerances, specific finishing requirements. In some circumstances such as highlighting a threaded hole, we can accept an annotated screenshot. To understand learn how to specify threads, see our threads terminology page, and our metric thread chart.
If you are looking for more details, kindly visit Custom Metal Shapes.
3) Get a Quote in 24 hours
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