What is Sheet Metal Fabrication?
Sheet metal fabrication is any process that involves assembling or manufacturing raw sheet metal. One or more fabrication processes can be used to produce the desired part, depending on the material and specifications of the project.
Sheet metal fabrication is a manufacturing technique that involves making products from flat metal sheets.
As a result, you can fabricate sheet metal using different methods involving advanced machinery to form, bend, cut, and assemble metal into any preferred shape.
The various sheet metal fabrication process is compatible with many metal materials. These include stainless steel, aluminum, copper, brass, zinc, and steel.
The thickness of these metal sheets ranges from 0.006 to 0.25 inches. Thinner gauges offer increased malleability, while thicker ones are perfect for heavy-duty applications.
In addition, sheet metal manufacturing works with the help of computer-aided design applications. It gives a 3D graphic representation of the end product of the production.
The 3D files are usually transformed into machine code (G-code) which controls the operation. Thus, the machine can make precision cuts, joins, and forms final products from different metal sheets.
How does sheet metal fabrication work?
There are several different ways to shape sheet metal, but they all boil down to two broad categories: sheet metal can either be cut or formed.
As there are many different ways of cutting and forming sheet metal, many specific tooling types are needed which can drive up costs.
This is why developing a good understanding of the various sheet metal fabrication processes available is essential to producing the most efficient design for a particular application is essential.
The most basic form of sheet metal fabrication begins with a flat sheet of metal and a blueprint (usually a DXF or CAD file). This blueprint will serve as the instructions on how to cut, form, and finish the base material.
It could be as simple as a single bend to turn it into angle iron, or laser cut and bent at the edges to make computer enclosure panels. When these processes are combined, the material is first cut and later formed, followed by finishing and joining.
Sheet Metal Fabrication Process.
Design
The design stage is where the groundwork for the project is laid out. Designers will usually create initial sketches or 2D/3D models of the product, which may be done using computer-aided design (CAD) software or by hand.
Important factors such as the intended use of the product, the required dimensions and tolerances, and any specific materials or finishes that will be needed are mapped out before the manufacturing begins.
Cutting
Laser cutting is typically the first step in the manufacturing process. Laser cutting is one of the most precise ways of cutting sheet metal as the lasers are able to follow the programmed design and cut through the material accurately.
Bending
The bending process is known as CNC folding and is a practice that can be completed using a variety of machines. For example, a manual press brake or automated panel bending machine.
The machine forms the metal part by clamping the sheet metal and applying pressure to maintain the desired curvature.
Forming
The forming process bends or deforms the material into the required shape. Different from cutting, which subtracts the material, forming actually reshapes the material without decreasing any of its mass.
Welding
There are a variety of welding techniques that can be used when working with sheet metal, including MIG welding, TIG welding, robotic MIG welding and spot welding.
- Metal inert gas (MIG) welding: A typically fast welding option that is better for thicker materials.
- Tungsten inert gas (TIG) welding: Offers greater control and precision than MIG. Best for thinner materials. You may also see it referred to as gas tungsten arc welding (GTAW).
- Robotic MIG welding: This is an automated version of more traditional MIG welding.
- Spot welding: This follows an electrical resistance welding process.
Finishing
Finishing is the last step when preparing metal products for use and makes products more resistant to corrosion, adding another layer of durability. It also helps make the surfaces look appealing.
Common finishing touches could include surface preparation, polishing and powder coating in a choice of colours, anodising, passivation, and laser marking (such as logos or etching some text).
Assembly
In a sheet metal fabrication project, assembly refers to the assembling of the required products before they are packaged and delivered to where they need to be.
6 Basic Sheet Metal Fabrication Techniques
#1. Metal Stamping.
Metal stamping fabrication works with various sheet metals. Galvanized alloys, brass, copper, aluminum, and stainless-steel stamping can be used to deliver the desired result.
Metal stamping is vital to manufacturing and assembling automotive components such as firewalls, doors, hubcaps, and trunk lids.
Metal stamping lends itself well to custom designs and features, such as high-performance and specialty components.
Metal stamping encompasses more than punching holes in sheet metal with a die. When necessary, a stamp and die can lift a sheet metal section, creating raised letters, shapes, and images on the surface.
This process works like woodworking and marble relief carving and is used in applications like minting coins.
#2. Metal Cutting.
Sheet metal cutting is often the first step in metal fabrication. Depending on the project specifications and thickness of the metal, a manufacturer chooses one of the following metals cutting methods:
- Water jet: A water jet cutter uses a high-powered water stream to cut metals of various thicknesses using a narrow, high-pressure water nozzle.
- Torching: A high-temperature flame from a cutting torch can cut metals prone to oxidization, including steel.
- Shearing: A sheet metal workpiece is placed flat and shears cut through it with two large scissor-like blades, pushing the workpiece toward the lower blade. Manufacturers can economically cut thin pieces of sheet metal with small manual shears.
- Sawing: Band and circular saws can cut sheet metal workpieces that are too thick for torches, water jets, and shears. Sawing is recommended for thick metal because it is time intensive.
#3. Metal Welding.
Welding metal involves joining sheet metal workpieces together by applying intense heat to bond the pieces.
The welding method depends on the equipment available, the metal type, and the material’s thickness. Manufacturers perform sheet metal welding using the following popular methods:
- MIG welding: A type of arc welding that relies on a continuous wire electrode being fed through a welding gun to generate a welding pool. A shielding gas protects the weld pool from contamination.
- TIG welding: An electric arc travels through an infusible tungsten electrode to generate intense heat, fusing 8- to 10-mm thick metal sheets.
- Laser welding: A method that fuses sheet metal workpieces by melting and bonding the metal with a solid-state laser resonator. Laser welding delivers high-quality welds with consistency.
#4. Metal Bending.
Metal bending is a vital step of sheet metal fabrication. Sheet metal is bent using bending equipment like press brakes and rolling machines.
Manufacturers rely on bending to shape the sheet metal into various products, such as by creating configurations like T-shaped corners and 90° angles.
#5. Metal Machining.
Machining is a subtractive manufacturing process that removes material from a workpiece to create a component.
While manual machining is still common, computer numerical control (CNC) machining is increasingly popular due to its speed, consistency, and tight tolerances.
CNC turning and milling are the most common processes. Turning relies on a stationary, single-point cutting tool to remove material from a rotating workpiece.
It is ideal for creating cylindrical pieces with high-precision external and internal elements.
Milling removes excess material using a rotating multi-point cutting tool on a stationary workpiece to create a component from start to finish or as a secondary finishing process.
Machining provides replicable, accurate, and precise material removal.
#6. Metal Punching.
Metal punching is a fabrication method that forms, cuts, and punches metal with a punch press as the workpiece passes through it.
A metal punching tool combined with a die set offers the versatility to create custom metal workpieces out of various metals. It is a cost-effective and efficient solution for high-volume production.
Sheet Metal Fabrication Cutting Techniques
Cutting is usually the first phase in the sheet metal fabrication process. You can cut different shapes or structures from rectangular metal sheets to meet design requirements. The main cutting techniques involved two categories: cutting without shear and with shear.
#1. Cutting Without Shear.
There are several processes that enable adequate cutting through sheet metal material without shear force.
These techniques involve extreme heat, high pressure, vaporization, and abrasive blasting to shape the sheet metal fabrication parts. They include the following:
Laser Cutting
Sheet metal laser cutting involves using focused laser beams to melt metals in localized areas. Laser cutters are compatible with a long list of metals, ranging from non-ferrous metals to mild steel and stainless steel.
This technique consists of two concurrently running sub-processes. The first one involves concentrating a high-powered laser beam on the sheet metal. The material absorbs the laser beam’s thermal energy, making it vaporize.
At the same time, the second process involves a cutting nozzle providing blowing gas for laser cutting.
This gas is usually oxygen or nitrogen. It helps to prevent the processing head from splashes and vapors during sheet metal fabricating engineering.
Plasma Cutting
Plasma cutting is a thermal cutting process involving metal with ionized gas called plasma.
The method uses substantial heat to cut the metal, which creates large burrs and an oxidized zone close to the cut area.
In addition, it allows faster cutting, high precision, and repeatability in sheet metal manufacturing.
The plasma cutting tool works effectively only on electrically conductive sheet metals. Consequently, it is one of the most suitable methods for cutting conductive materials with medium aluminum thickness.
Waterjet Cutting
This cutting process involves using a high-pressure stream of water to cut metal sheets. Waterjet cutting is versatile and can cut various hard and soft materials using pressurized water and abrasive.
It is ideal for cutting soft materials, metal foils, fabrics, or rubber. At the same time, it is suitable for cutting hard materials like copper, carbon steel, aluminum, and carbon steel.
The pressure involved is usually about 60,000 psi, with a 610m/s supply of velocity to cut through different types of metal sheets. However, waterjet cutting is a better substitute for the laser cutting technique.
#2. Cutting With Shear.
The processes under this category cut metal materials using shearing force to overcome the metal’s ultimate shear strength.
They usually involve using dies, punches, and shear presses to enable adequate cutting of the metal. The techniques here include the following:
Shearing
Shearing is suitable for high-scale applications and cutting soft materials that don’t need clean finishes, like brass, aluminum, and mild steel.
It cuts straight lines on sheet metals with a flat surface. The shearing method involves applying a shear force on the surface, causing the flat metal material to split at the cutting point.
This is often the ideal process for making straight edges on a metal sheet with rough edges. It is cost-effective for high-volume operations when manufacturing thousands of sheet metal fabrication parts within a short lead time.
However, shearing may not be perfect for applications that need quality finishes due to the burrs and material deformations it causes.
Punching
Punching uses shear force to make holes in the sheet metal. In this sheet metal fabrication process, the scrap material is the material removed from the hole, while the final component is the remaining material on the die.
Punching is suitable for making cutouts and holes of different shapes and sizes. However, using the punching process can take much time. You have to match the dies and punching knives correctly.
Blanking
Blanking is an ideal process for economic sheet metal fabrication. It involves removing a portion of sheet metal from a larger piece of the stock material using a blanking punch and die.
The punch makes a “blanking force” through the sheet metal while the die holds it during the process.
The extracted material is the preferred component, while the remaining material on the die is the leftover black stock.
This process is suitable for making economic custom parts due to its high repeatability, dimension control, and excellent accuracy.
Sawing
Sawing cuts metal materials using a sawtooth tool to create a series of tiny cuts in the metal. A sawtooth uses shear force and friction to tear apart a small part of the metal material.
Band saws have various fine and marginally bent teeth suitable for cutting brass, aluminum, and other non-ferrous sheet metal.
Horizontal band saws help to cut longer bar stocks to desired sizes. On the other hand, vertical band saws help to achieve complex cuttings that need accurate contours in the metal parts.
Types of Sheet Metal
1. Aluminium: Used for automotive parts, electrical devices, and cooking vessels. Offering numerous benefits including a good strength-to-weight ratio, and high conductivity.
2. Aluminised steel: This metal combines the high strength of carbon steel with aluminium’s superior corrosion resistance. Sheets of aluminised steel are used for products intended for high-temperature environments, such as kitchen appliances.
3. Carbon steel: Carbon steel is used in the industrial and consumer markets for a range of products. It is a steel alloy that contains carbon, resulting in the material increasing in hardness and strength when it undergoes heat treatment.
4. Copper: Examples of products made from copper are sinks, roofs, rain gutters, and doors. Copper features higher electrical and thermal conductivity in comparison to aluminium but can be more expensive.
5. Galvanised steel: Sheets of galvanised steel tend to be used for making automobile bodies, water pipes, fences, roofs, and staircases. It is made by coating steel with zinc through a hot dipping process, helping to make it more corrosion-resistant.
6. High-strength steel: Military armour plates tend to be made from sheets of high-strength steel. The material is produced by alloying steel with a range of elements such as carbon, manganese, and copper. This helps to improve its hardness.
7. Stainless steel: Used for kitchen vessels, storage tanks for chemicals and food processing machinery. Stainless steel offers superior corrosion resistance, fire and heat resistance, strength-to-weight ratio, and manufacturability.
8. Titanium: Typical products made from titanium include aviation parts, medical equipment, and construction elements. It is primarily used for its high strength-to-weight ratio and corrosion resistance. It is also recyclable.
Benefits and limitations of sheet metal fabrication
As the term sheet metal fabrication covers a wide range of processes and techniques, the advantages and disadvantages very much vary depending on the process.
Below is a general snapshot of the benefits and drawbacks of fabricating sheet metal, but to have a more complete understanding of whether a particular sheet metal fabrication process is suitable for your application, more research into each individual process is needed.
Benefits of Sheet Metal Fabrication
1. Fast, affordable, and high quality for production or prototyping.
Fabrication can quickly produce prototype parts with the same precision and speed that it can produce in production.
It can also be easily customized, so if the first design doesn’t work as planned – no sweat – the very next part can be adjusted.
This customization aspect makes sheet metal versatile, flexible, and affordable when it comes to custom part creation.
When parts approach high volumes, sheet metal becomes even cheaper per-part with exceptionally consistent results.
2. Vast number of techniques and materials.
In this article alone, fourteen types of sheet metal fabrication are mentioned. These varying techniques allow make it possible to create relatively complex parts by cutting flat sheets, bending parts into place and adding holes, slots, and notches cut in all the right places.
Together with the wide range of compatible materials and its ability to withstand (even thrive) in high heat, thermal conduction, electrical, and corrosive environments, sheet metal can be suitable for a diverse number of applications.
3. High strength to weight ratio.
Sheet metal can be useful when trying to keep a project lightweight. Adding bends to sheet metal increases the structure’s strength tremendously because it increases the stiffness in multiple axes. Adding a finish to the sheet metal can also make the material resistant to corrosion and scratches.
Limitations of Sheet Metal Fabrication
1. Capability limits per technique.
Each technique has limits that make combining different processes a necessity. This can be an advantage, but it can also create longer processing times.
For example, a laser cutter cannot make tiny holes, so a drilling or punching process would have to be included.
2. High initial capital for tooling and equipment.
Some processes, like stamping and roll forming, require custom tooling and equipment to be created to run the process.
These custom tools can sometimes be very pricey and only profitable when manufacturing lots of parts.
3. High labor cost for some types.
Some processes require much manual labor, which can drive up the cost per part. Automation can cut down on this labor time cost but is only feasible when high quantities are required.
4. Bending operations designs are intricate.
Bending can be a convenient operation since 3D parts can be created from flat sheets. However, it can also be very complex due to the calculations or trial-and-error aspect of the design cycle. If hole and shaft alignment is necessary, it’s not always straightforward.
Industrial Applications of Sheet Metal Fabrication Parts
Several industries use sheet metal fabricated parts in their daily operations. Here are some of these industries:
1. Automotive.
The sheet metal fabrication process paved the way for the innovative design of automobiles due to the availability of production-grade materials.
The metal-forming capabilities of this technology help create perfect frames from thin metal sheets.
Hence, most car parts undergo punching and laser operations. For example, most vehicles’ hoods, fenders, side panels, and roofs are sheet metal engineering products.
2. Aerospace.
Custom sheet metal fabrication facilitates the production of several space-worthy components and lightweight parts.
Components used in the aerospace industry usually require tighter tolerances and high precision.
Therefore, you can combine metal sheets like aluminum and steel with improved methods to create complex spacecraft and aircraft designs.
3. Healthcare.
Sheet metal engineering helps to detect design errors and proffer reliable solutions due to medical tools’ quality and accuracy demands.
Sheet metal prototyping and manufacturing are ideal for MRI applications and for producing scalpels and surgical instruments.
You can automate these processes to prevent human error and improve accuracy in fabricating medical devices.
4. Enclosures.
Sheet metal fabrication helps produce economic housing enclosures to safeguard sensitive gearboxes and equipment.
In addition, fabricated parts protect tools from the environment, preventing dust from getting in.
Likewise, using sheet metal fabricating techniques, you can make various cut outs for cable connections, such as glass windows, LED panels, light pipes, and HDMI.
When to Use Sheet Metal Processing
1. Low Part Volume.
When you need a relatively small quantity of parts or components, sheet metal processing can be a cost-effective choice.
It allows for efficient production of low to medium volumes without the need for expensive tooling or molds, making it suitable for prototyping and small batch production.
2. Size.
Sheet metal processing is ideal for creating parts of various sizes and thicknesses. Whether you need large panels or small brackets, sheet metal can be cut, bent, and formed to meet your size requirements.
3. Intricate.
Sheet metal processing allows for the creation of intricate and complex shapes with high precision. CNC (Computer Numerical Control) machines can be programmed to cut and form sheet metal with intricate patterns, holes, and features.
4. Multiple Forming Steps.
If your design requires multiple forming steps or operations, such as bending, punching, and welding, sheet metal processing is well-suited for such tasks. The process can be broken down into various stages to achieve the desired final shape.
5. Frequent Adjustments.
Sheet metal processing offers flexibility in making adjustments to the design or production process. Tooling can be modified relatively easily to accommodate changes in design or specifications, making it suitable for projects with frequent adjustments.
6. Prototyping.
Allows for rapid iteration and modification of designs without the need for costly tooling changes. CNC machines can quickly adapt to new designs, making it ideal for testing and refining prototypes.