Sheet metal fabrication is the process of turning flat sheets of steel or aluminium into metal structures or products, by cutting, punching, folding and assembling. Sheet metal can be cut, bent or stretched into nearly any shape, which is generally done by cutting and burning the metal.
The first step in a sheet metal fabrication is the actual cutting and shaping of the material. In this sense, sheet metal fabrication can be considered a subtractive manufacturing process (like CNC machining), because usable parts can be made by simply removing sections of material.
The cutting processes used in sheet metal working are sawing, milling, filing, drilling, broaching, and thermal cutting. All of these methods are separating processes. To do these processes, the sheet metal is cut with relative movements. This enables power from outside sources to convert into friction and deformation. The process of cutting involves using different kinds of tools and machines. For example, hand tools are used for shaping, sanding, and shaping. Power tools are used for drilling, shearing, and welding.
Sheet metal fabrication: Cutting
Manufacturers can cut sheet metal using a variety of different pieces of machinery, some of which are unique to sheet metal fabrication.
One of the key methods for cutting sheet metal cutting is laser cutting, a laser cutting machine is the most common one. Engineers and designers prefer this machine because the traditional process can be time-consuming.
A laser cutter uses a powerful laser intensified with a lens or mirror and accurate cuts. It is a precise and energy-efficient machine, that can create intricate shapes and small holes in sheet metal, suitable for thin or medium gauges of sheet metal but may struggle to penetrate the hardest materials.
The laser cutter machine is similar to the shaper but has a stationary cutting tool and linear motion, it uses a focused beam of light to cut sheet metal, its speed is high, around 20 to 70 inches per second, and has the advantage of cutting a wide range of materials in a short amount of time. Moreover, Its accuracy allows for extremely precise cuts and tight tolerances and can create precise small cuts and very tight tolerances, they are great for the precise cutting of sheet metal. Moreover, these machines don’t leave any burrs on the edges of the metal, making polishing and buffing easier.
Water jet cutting
Water jet cutting is a sheet metal fabrication method, that uses a high-pressure jet of water (mixed with an abrasive substance) to cut through the metal to make a precise and accurate cut, a water jet machine can be used to cut almost any type of 2D shape out of sheet metal. Water jet cutters are particularly useful for cutting sheet metals with a low melting point since they do not generate heat which could unduly deform the metal. Additionally, this type of cutting doesn’t cause any burrs.
Water jet cutting machine
A water jet cutting machine is a type of water jet that can cut almost any shape out of sheet metal. The width of a water jet cutter is usually between 0.02-0.06 inches. The machine produces clean edges and does not require secondary finishing. The main benefit of waterjet cutting is that it does not produce chips. It is a very precise and flexible machine. Its adjustable pressure and guide arm make it a versatile machine for any application.
A third sheet metal cutting option is plasma cutting. A plasma cutter creates an electrical channel of ionized gas which forms a jet of hot plasma that easily penetrates even thick gauges of sheet metal. Although less accurate than laser or water jet cutters, plasma cutters are fast and powerful with low setup costs.
These three cutting machines can be used on other materials besides sheet metals, but there are some techniques used solely for sheet metal fabrication.
The process of punching (sometimes called piercing), for example, creates precise holes in sheet metal using a punch and die. The sheet metal is placed between the two components, and the punch forces itself through the metal to reach the die.
In the punching process, the punched circular pieces of removed material are turned into scrap, but these circular pieces can also be used as new workpieces: this is called blanking.
Manufacturers use blanking to punch pieces in specific shapes from sheets or strips of raw material. The punched-out piece is called the “blank,” hence the term “blanking.” Blanking is most often performed with tools made from hardened steel or carbide, which work on metals like aluminum, carbon steel, stainless steel, and even plastic.
Blanking has many benefits, but manufacturers must take some considerations into account before embarking on a full course of metal blanking. Although this process is a quick and cost-effective way to produce a large number of identical pieces, these punched-out pieces may have burrs or cracks on the edges. However, these drawbacks can be avoided by using high-quality tools, and they can be corrected by post-processing the blanks.
Benefits of Blanking
Machinery used for blanking ranges from simple punches and dies to sophisticated CNC machinery. Blanking equipment can quickly be configured to end product specifications, and the process itself takes little time per part as it involves simply feeding the primary metal stock continuously into the blanking machine.
Because of this, blanking can perform long production runs that require little or no changes to the machinery or base material. The straightforward process also allows you to construct materials to strict tolerances with little part-to-part variation, and technology has become so sophisticated that it can build multiple geometries using a single process.
Furthermore, because the primary metal stock can be reused, blanking can help manufacturing firms reduce their material waste. Due to these benefits, blanking is commonly used to mass produce components for industries such as aerospace and automobile manufacturing. It’s also used for high-volume fabrication of parts for common household appliances.
5 different Types of Blanking Methods
Compound Die Stamping
This type of blanking is used to precisely manufacture complex steel parts. In this process, workers or automated equipment feed a steel strip through the stamping machine, which punches out a blank every three seconds. This simple, precise, and fast technique enables firms to produce steel components in bulk.
Continuous Strip Blanking
As implied by the name, continuous strip blanking continuously feeds metal substrates through a machine. This allows punching machines to produce uniform end products around the clock, with each product having the same characteristics of those before and after it. This process is a great way to develop coins, bottle caps, and medallions.
Progressive Die Stamping
Progressive die stamping uses coiled strips of thin flat metal as its base material. In this process, progressive die machines sequentially stamp, trim, and bend workpieces to make the finished parts, which exit the machine in conjoined strips. After performing this task, the machine separates individual parts from the strip, which results in the creation of several identical parts.
Square Sheared Blanking
Square sheared blanking is a fine process that uses specialized clamping tools to produce square-edged and contoured blanks. This process is a great way to create panels, casings, and any other component that requires a uniform square shape.
This process combines metal cutting and metal blanking procedures to create highly specialized blanks. When cutoff blanking, manufacturers blank metal sheets and then cut the metal at the sheets, allowing the production of long, flat pieces.
Best Materials to Use When Blanking
Performs blanking on carbon steel, stainless steel, and aluminum. Each material brings unique properties to the process.
Metalworkers use carbon steel to make industrial equipment and household tools like knives because of this material’s exceptional strength and hardness. Carbon steel’s hardness varies depending on the amount of carbon present within it, and the higher the carbon content, the harder the alloy is.
Carbon content in carbon steel ranges from 0.8% to 2.11%, and the typical value is about 1.5%. Carbon steel is more cost-effective than other materials of comparable hardness, thus making it a popular raw material to use as a substrate, such as a sheet metal, angle iron.
Stainless steel has low carbon content but a large amount of chromium, which ranges from 10% to 30% of the final material. This chromium content makes stainless steel highly resistant to corrosion and heat.
Stainless steel may also incorporate other metals like aluminum, copper, and titanium to enhance various attributes, and even nonmetals like phosphorous and sulfur can be used to improve resistance to certain types of corrosive substances. Stainless steel is thus a versatile alloy that can take on a variety of uses depending on its composition.
Aluminum’s softness and flexibility make it very suitable. In fact, aluminum is the most common metal used to create industrial and household products because of this material’s low cost, ease of extraction, and properties like lightness, durability, and recycling potential.
For these reasons, many applications in the automotive, aerospace, energy, and packaging industries use aluminum in large quantities. Aluminum is a very cost-effective way to produce high volumes of components.
This cutting process uses a drill bit to create a hole with a specified diameter. Depending on the diameter of the hole, it can produce a perfect circle. Thread-tapping: This process produces threads inside the drilled hole. Countersinking: This process removes the sharp edge from a drilled hole and creates a deep level for the blind bolt head. Hardware insertion: This type of sheet metal fabrication is a great way to provide a higher-quality thread for load-bearing applications.
When metal is cut, it is typically not shaped as desired. The process of drilling and forming leaves rough edges and sharp spots on the component’s surface. Post-processing includes polishing and rinsing. Depending on the project, the component may be painted or coated. These coatings can protect against corrosion, UV rays, and heat. Assembling is the last step in a sheet metal fabrication service. This final step involves attaching the components and ensuring that all parts are connected.
When creating many holes, similar equipment can be used for the perforation of sheet metal.
Differences Between Punching and Blanking
Punching and blanking are often confused with each other since both processes remove pieces from a base sheet of material. Adding to the confusion is the fact that the same terms, punch and die, are used in both operations.
A simple way to remember the difference between the two processes is to note that an alternate term for punching is piercing. Manufacturers sometimes refer to this process as piercing because the desired end product is the pierced sheet of metal, not the metal that’s been punched out of it.
As discussed above, the punched-out slugs created by are the end products of the process, and unused sheet metal is discarded or reused after the slugs have been obtained.
There are many other operations that follow, but differ from, the basic process. Some of these include:
- No matter the type of hole-punching process used, it will result in quality parts at tight tolerances.
Sheet metal fabrication: Deformation
Another major category of sheet metal fabrication processes is sheet metal deformation. This group of processes contains myriad ways to change and manipulate sheet metal without cutting into it.
Sheet metal bending
One of the main deformation processes is sheet metal bending. Using a machine called a brake, a sheet metal company can bend sheet metal into V shapes, U shapes, and channels to an angle of up to 120 degrees. Thinner gauges of sheet metal are easier to bend. It is also possible to do the opposite: sheet metal manufacturers can remove the horizontal bend from strip-shaped pieces of sheet metal with the process of decambering.
The process of stamping is another deformation process, but it can also be thought of as a subcategory of its own. It involves the use of a hydraulic or mechanical stamping press equipped with a tool and die, and its operation is similar to punching — though the material does not necessarily have to be removed. Stamping can be used for specific tasks like curling, drawing, embossing, flanging, and hemming.
Spinning is a sheet metal fabrication process unlike other deformation techniques in that it uses a lathe to rotate sheet metal as it is pressed against a tool. The process looks similar to CNC turning or even pottery spinning, and it is useful for creating rounded sheet metal parts: cones, cylinders, etc.
bending, stamping, Spinning, and sheet metal fabrication methods less common sheet metal deformation processes include wheeling, which is used to make compound curves in sheet metal, and rolling, in which sheet metal is fed between a pair of rollers to reduce its thickness (and/or increase consistency in thickness).
Some processes sit halfway between cutting and deformation. For example, the process of sheet metal expansion involves cutting multiple slits in the metal and then stretching the sheet open like an accordion.
Sheet Metal Bending
Sheet metal bending is an operation that involves using forces to change the shape of a sheet. This is done to achieve the desired form or shape needed for a manufacturing process. The external force used alters only the external features of the sheet it is an effective way of making products with different shapes used for different processes, Also known as press braking, flanging, die bending, folding, and edging.
It guarantees simplicity and it is an efficient way of forming new products.
Read more: An introduction to 12 types of sheet metal bending processes
Sheet metal fabrication: Assembly
Sheet metal cutting and deformation are two ways of forming sheet metal. A third way is an assembly, either by using common fasteners or by other methods.
Although it is not always considered a fabrication process, the assembly of disparate components of sheet metal parts using fasteners bolts, screws, and rivets is an important part of the overall manufacturing process. Other sheet metal fabrication processes like punching may be carried out explicitly to make holes for rivets and other fasteners.
Sheet metal components may also be joined together using the process of welding, in which heat is applied to melt a section of the metal where it joins with another component. The melted metal of the two components fused to form a solid connection. Common sheet metals like stainless steel and aluminum have good weldability, although different metals may weld better with certain types of welding: arc, electron beam, resistance, etc.