‘A close-up process of welding two steel sheets’
Metal sheet fabrication for steel is nothing new. It has been around for decades and continues to evolve. This process involves building functional components from raw steel sheets which are usually large and thick. It utilizes specialized tools and equipment to create complex three-dimensional shapes.
There are various techniques of steel sheet fabrication. Many times, you may need more than one to achieve the desired result. It is important to understand how each process works before using it. This article will explain what sheet metal fabrication for steel is, the different processes available, and the most common types of steel ideal for sheet metal fabrication.
What is Sheet Metal Fabrication of Steel?
Steel sheet metal fabrication is the process of turning sheets of steel into the desired shape. It involves various techniques such as bending, cutting, or joining to create durable steel parts at a low cost. To carry out this process, you have to design a model of the final part. Thereafter, mount the workpiece and required tools appropriately. Then, cut, punch, bend, and weld the part as required. The final step entails using suitable finishing processes and assembling the finished product.
When compared to most manufacturing operations, you will find out that metal fabrication of sheet steel is less expensive. Additionally, it produces lightweight parts making it ideal in industries such as aerospace and automotive where fuel efficiency is a concern.
Processes in Steel Sheet Metal Fabrication
In this section, we will discuss the different processes you can use to fabricate steel sheets.
- Cutting
Cutting involves removing excess material from a workpiece to shape it. It can either require mechanical forces to shear the part or without a shear force
Shearing
Shearing involves the application of force to split the material along the desired path. You carry out this process by placing the workpiece in between the cutting tools. This force must overcome the shear strength of the material to separate it. Shearing is ideal for applications that do not require a smooth surface finish. It can come in the form of sawing, blanking and punching.
Non-Shearing
There are other techniques you can use to remove excess material from a workpiece without shear force. The most common processes include laser cutting, plasma cutting, and waterjet cutting
Laser cutting: It uses a high-power laser beam to cut through materials. Laser cutting is a noncontact process that creates patterns with a high-quality finish.
Plasma cutting: This process uses a jet of hot plasma to melt steel sheets. Plasma cutting is fast and has a small heat-affected zone.
Water jet cutting: It employs a mixture of abrasives and high-pressure water steam to cut tough a sheet of steel. Water jet cutting is very accurate and results in smooth and burr-free edges.
- Forming
Forming involves various techniques that mechanically deform metal components to get the desired shape and size. It operates on the principle of plastic deformation and does not add or remove any material. There are four main steel sheet-forming techniques you can use; bending, stamping, rolling, and hemming.
Bending
It utilizes machine presses to bend steel sheets at a required angle. This results in a U or V-shaped part. There are two types of bending
- Press braking and
- Roll bending.
Roll bending uses matted rolls to continuously bend long strips of steel. It is suitable for detailed and complex cross-sections. On the other hand, press braking uses punches and dies to form parts with specific shapes and angles.
Stamping
This is a forming process that fabricates a steel sheet into the desired shape using a stamping press. It involves various operations such as blanking, bending, embossing, and coining. You can carry out these techniques simultaneously or sequentially. Steel sheet metal stamping ensures repeatability in high-volume production. However, it generates a high scrap rate and comes with expensive mold costs.
Rolling
This technique involves passing the metal sheet into two rollers that are rotating in different directions. Rolling sheets of steel aim to reduce thickness and ensure thickness uniformity along the part. There are two types of rolling;
- Hot rolling and
- Cold rolling.
The difference is the temperature at which you carry them out. Cold rolling occurs near or at room temperature. On the other hand, you carry out hot rolling at a temperature higher than steel’s recrystallization temperature, usually at 538 degrees Celsius.
Heming
Hemming involves rolling a steel sheet onto itself. This helps to conceal flaws, increase strength, and improve overall appearance. A hem can either be opened or closed. An open hem gives allowance for space in the bend while a closed hem doesn’t. They both help to stiffen edges and make steel parts safer for handling.
- Joining
Joining is another process of fabricating steel sheets. It involves creating a permanent or temporary joint between two or more components. You can either fuse them by welding or with the use of fasteners.
Welding
Welding uses heat, pressure, or both to join steel sheets together. It is a permanent process and can fuse steel parts with other types of metals. There are three main types of welding you can use in steel sheet fabrication. They include
- Gas metal arc welding
- Gas tungsten arc welding
- Shielded metal arc welding
They differ based on the electrode used to form the weld, shielding gas, and general application.
Fastening
Fastening is a mechanical process that uses fasteners to create permanent and nonpermanent joints. The most commonly used fasteners are screws, nuts, bolts, threaded inserts and rivets. They increase efficiency, allow for quick installation, and are aesthetically pleasing.
- Finishing
Finishing is usually the last step in steel sheet fabrication. This step is important to enhance appearance and improve corrosion and wear resistance. It also promotes adhesion and aids easy cleaning. There are different finishing techniques available for fabricated steel sheets. Some of the most common ones include coating, plating, and polishing. The one you use depends on the purpose and what you are trying to achieve.
Types of Steel Used in Sheet Metal Fabrication
‘Stainless steel laser cutting process’
There are different types of steel manufacturers use. Most are suitable for metal fabrication. However, there are a few exceptions. The use of tool steel is limited because it may be difficult for beginners to work with it as it increases wear and tear on tools. When fabricating steel sheets, go for any of the types described below.
Carbon Steel
Carbon steel is a popular choice in sheet metal fabrication. It is adaptable and retains its mechanical properties when you work on it. Generally, carbon steel contains iron as the base element and 0.12 – 2% carbon. Note that there are different grades of carbon steel based on the carbon content. The more the carbon content, the harder it is and the lower the melting point.
Low Carbon Steel
It contains 0.12%-0.29 carbon. As a result, it is more ductile and you can easily fabricate it. Low carbon steel has uses in flat rolled components such as vehicle body panels and wires.
Medium Carbon Steel
This type has a carbon content between 0.30 to 0.59%. In certain instances, it may contain additional manganese content making it possible to quench and temper it easily. One can use medium carbon steel for gears, crankshafts, axles, and many other automotive parts.
High Carbon Steel
The carbon content in high-carbon steel is from 0.6 – 1%. The physical properties of high-carbon steel differ from the types we’ve previously described. It has applications in manufacturing springs, knives, and swords. When using high-carbon steel, it is important to coat the fabricated parts because of the tendency to rust.
Ultra High Carbon Steel
It has a very high carbon content ranging from 1.25 to 2%. It is the most durable and has a tensile strength of up to 1100 MPa. This makes it the most suitable option when producing axles and punches.
Stainless Steel
Stainless steel is another type you can use when carrying out sheet metal fabrication. It is easy to manipulate and work with. Stainless steel contains iron, about 10.5% chromium, and a carbon content usually less than 1.2%. The high chromium content makes it stable when exposed to corrosive environments. There are over 150 grades of stainless steel available. They are usually grouped under three main types
Austenitic
Austenitic stainless steel sheets are nonmagnetic and you can alter their shape easily without deforming. Common grades under this type include 301, 304, and 316. However, engineers use #304 the most because it is affordable and highly resistant to corrosion.
Martensitic
This type has a martensite crystal structure. Martensitic stainless steel retains its magnetic properties when hardened or annealed. However, it has limited weldability and formability properties. Martensitic stainless steel comes in different grades; 410, 420, and 440 are the most sought-after.
Ferritic
Ferritic stainless steel has a low carbon content usually 0.2%. For this type, you may need special skills to harden and temper it using any form of heat treatment. However, it may be the go-to sheet if you want to use the part in oxidizing environments. It is loaded with up to 27% chromium which increases its resistance to harsh chemicals.
Alloy Steel
The last classification is alloy steel. It contains other elements such as aluminum, nickel, and copper to improve its mechanical properties. Alloy steel maximizes the benefits of these elements. As a result, they are harder, stronger, and wear-resistant. There are two types of alloy steel you can use for sheet metal fabrication. They have a varying percentage of alloying elements and unique applications.
Low Alloy Steel
It contains less than 8% additional elements. Hence, it is suitable for piping systems and railway lines
High Alloy Steel
This type has more than 8% alloying elements. It has applications when manufacturing components of power-generating equipment.
Applications of Steel Sheet Fabricated Parts
The following are some common practical applications of steel sheet fabricated parts.
Automotive Components
Steel sheet fabrication is revolutionizing the automotive industry. You can use various grades of stainless steel and carbon steel. You would find it in body panels, chassis components, and seat structures.
Consumer Goods
Steel sheet fabrication is a cost-effective option when compared to CNC milling. It produces durable and high-quality parts such as metal frames for tables, chairs, and components of gym equipment. These steel fabricated parts are of a high quality and are easy to maintain.
Agriculture Equipment
Steel sheet fabrication is an important technique in building farm equipment and machinery. These include tractors, harvesters, silos, and storage bins. These parts are strong and can withstand demanding tasks.
Aerospace Parts
Steel is one of the most common metals that aerospace manufacturers use. Aerospace sheet fabricated parts include engine covers, fuselages, and wings. Steel sheets are tough and provide an excellent strength-to-weight ratio.
Conclusion
Steel sheet metal fabrication is a combination of different techniques that helps to shape parts. It is a cost effective way of producing light weight and durable components. Additionally, it is versatile process as there are many steel grades you can use. However, you have to carefully consider the properties of the different types of steel before using any.
