What Are the Different Types of Sheet Metal Fabrication Techniques?

Sheet metal fabrication plays a critical role in product development. It is a multifaceted process that shapes and forms metal sheets into finished products. Part manufacturers use sheet metal fabrication extensively when creating components, including turbine blades, engine components, orthopedic implants, and surgical instruments. The final parts are lightweight and come with micron-level precision.

Furthermore, sheet metal fabrication encompasses many techniques, from cutting and forming to joining and finishing. Each process has unique advantages and serves varying roles. This article will explain what sheet metal fabrication is and the various techniques you can use to optimize part manufacturing.

What is Sheet Metal Fabrication

Sheet metal fabrication involves a wide range of techniques that transform thin sheets of metal into valuable and sturdy products. It entails cutting, bending, and joining metal sheets to produce parts with complex shapes and designs. Sheet metal fabrication is accurate and precise, as most methods are automated. It is suitable for industries such as aerospace and healthcare with tight tolerance requirements. 

Furthermore, sheet metal fabrication is versatile and compatible with many engineering materials. You can use it for aluminum, steel, copper, and nickel alloys. The final parts are also durable and have a high strength-to-weight ratio. 

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Cutting Sheet Metal Fabrication

Cutting is usually the first step in sheet metal fabrication. The cutting methods are divided into shearing and non shearing 

• Cutting With Shearing

Cutting with shearing involves applying force to remove the unwanted parts of a metal sheet. The shear force must be greater than the shear strength of the material for a cutting action to occur. Punching, sawing, and blanking come under cutting with shearing

Punching

Punching uses a punch and die set to create consistent holes in the workpiece. To carry out punching, you force the metal sheet into the die to remove excess material. This is useful when making decorative patterns or holes for different types of fasteners. 

Sawing

The tool here is a manual or electrically powered saw blade that cuts through a material. You can make different cuts when dividing the sheet metal into smaller sections. Sawing is adaptable and can work with materials with varying thicknesses.

Blanking

Blanking is similar to punching. However, the blank is useful, and you discard or recycle the surrounding material. Blanking is used when fabricating washers and gears. It is highly efficient and produces parts with uniform sizes and shapes.

• Non-Shearing Techniques 

You don’t have to always use a shear force when cutting sheet metals. Some techniques employ other means to get more complex and accurate cuts. These non shearing methods are

Laser Cutting 

This entails using a highly focused laser beam to cut through the workpiece. Rather than cutting, this technique involves melting and vaporizing to produce smooth edges. Laser cutting is noncontact and results in a small heat-affected zone. You can use it for high-precision cuts and intricate designs.

Plasma Cutting 

Another method you can use is plasma cutting. Here, a plasma torch generates a high-temperature jet of ionized gas to melt material along the cutting path. This can cut thick sheets of conductive metals. Plasma cutting is fast and produces smooth finishes.

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Water jet Cutting 

The tool here is highly pressurized water used alone or with abrasives. Waterjet cutting does not need any form of heat to work, making it ideal for heat-sensitive materials. However, the major downside of water jet cutting is its relatively slow speed.

Oxy-Fuel Cutting 

As the name implies, you use a mixture of oxygen and fuel gas to cut sheet metals. When combustion occurs, the flame heats the metal and causes it to oxidize. The result is a clean cut that may not need further processing.

Forming Sheet Metal Fabrication

Forming is another way one can manipulate sheet metals. Here, you don’t cut or join metals. Instead, you produce the desired shape while the workpiece is in solid state. The five commonly utilized forming techniques are bending, rolling, stamping, hemming, and curling.

• Bending

The bending process uses force to create angular and curved shapes. You carry out bending with tools like dies and press brakes. There are two types of bending: air and bottom bending. Air bending partially presses the metal sheet on the die. On the other hand, there is no space between the die and the workpiece with bottoming. Bending has applications in manufacturing enclosures, frames, and brackets.

• Rolling

To carry out rolling, pass the metal sheets through a pair of rollers to reduce their thickness and create a cylindrical shape. Rolling can either be hot or cold, depending on the operating temperature. Hot rolling occurs above the recrystallization temperature of the workpiece material. For cold rolling, you carry out the process at room temperature. You use rolling when fabricating pipes and cylindrical tanks.

• Stamping

Stamping is a cold sheet metal forming technique that involves placing the workpiece in a stamping press. You apply enough force to press the sheet metal into the desired shape to create fine details. The stamping process is fast and produces consistent results. Additionally, it produces minimal waste. However, stamping has a high initial cost with limited design flexibility.

• Hemming

Hemming describes the process of folding the edge of the metal onto itself to improve aesthetics and make the part safer when handling. You can partially or entirely flatten the edge to remove the gaps. Alternatively, it is possible to create looped and teardrop-shaped edges. Hemming strengthens the edges and makes them more sturdy. This process is applicable when making automotive body panels and consumer goods.

• Curling 

In sheet metal curling, you create a circular roll on the workpiece edge for decorative and functional purposes. You carry out the curling process gradually until the loop closes. Curling is fast and reinforces the strength and structural integrity of the part. You use it to achieve smooth edges for door handles, decorative structures, and HVAC systems. However, you need specialized dies to get consistent curls. 

Joining Sheet Metal Fabrication

Joining is usually the last step in sheet metal fabrication. It entails everything that deals with fusing two or more pieces together to make a whole. The two broad categories of sheet metal joining techniques are welding and riveting.

• Welding 

Welding is a common way of joining metal sheets. The most popular methods are TIG, MIG, and laser welding 

TIG Welding 

Tungsten inert gas welding is an arc welding process that produces clean and high-quality welds. It creates an electric arc between the non consumable tungsten electrode and the workpiece. The electric arc heats the workpieces and joins them after cooling and solidification. TIG welding has low heat input, which reduces the risk of warping.

MIG Welding 

Metal inert gas welding is another arc welding technique. Here, you feed the consumable wire through a gun. When an electric current is applied, you bring the gun close to the workpiece to initiate the arc for the welding. When MIG welding, it is essential to use an inert gas to protect the weld pool from contamination. Compared to TIG, MIG welding has higher heat input and produces more spatter.

Laser Welding 

This process uses a high powered laser beam as the heat source. You generate the laser beam using a fiber or CO2 laser, depending on the material you are working on. After that, the laser beam is focused and used to melt the workpiece above its melting point. The parts fuse when they cool and dry. Laser beam welding is accurate and very precise. It is fast and does not cause warping or distortion.

• Riveting 

Riveting is a metal fastening method that does not use heat or pressure. It is a permanent process that creates strong joints. The riveting operation begins with punching holes in the workpiece to ensure proper alignment. You then place the rivet in the pre-drilled hole and deform the tail. It flattens out and holds the two parts firmly. The lack of heat input in riveting preserves the workpiece properties.

Finishing Sheet Metal Fabrication

Most of the time, the surface finish after sheet metal fabrication is unsuitable for aesthetics and functionality. In cases like this, you must use one or more finishing techniques to maintain standards. The following are common sheet metal finishing methods.

• Mechanical Finishing 

This involves techniques like grinding, polishing, and brushing that remove surface irregularities such as burrs and seams. They help to smoothen edges and create a uniform finish. Mechanical finishing usually prepares the parts for painting or coating. 

• Chemical Finishing

You can also chemically finish a workpiece by pickling or anodizing. Pickling uses an acidic solution to remove scales and oxides. Furthermore, anodizing describes the conversion of a metal surface to an anodic oxide finish. Anodizing increases wear and corrosion resistance.

• Coating and Plating

It is possible to coat and plate sheet metal pieces as needed. The three techniques under this are powder coating, wet painting, and electroplating. It involves applying an extra protective layer for a durable and aesthetically pleasing finish. 

Conclusion 

Sheet metal fabrication is an accurate means of creating intricate and sophisticated products. It involves cutting, forming, joining, and finishing thin sheets of metal materials. Most times, you do not use one technique alone. The sheet metal fabrication methods work hand in hand to optimize the production process. Before using any sheet metal technique, you should understand how it works to make the most of it. Do you have questions or inquiries? Reach out to a reliable sheet metal fabricator today.