Sheet Metal fabrication is the creation of useful metallic parts and structures by the application of multiple fabrication processes. Sheet metal fabrication is basically broad term that involves various complex processes like cutting, forming, bending, welding, machining, and assembling. Fabrication shops or Fab shops are the places where the processes related to sheet metal fabrication are performed. In this article, we will explore about the materials, processes and tools required for sheet metal fabrication.
What is Sheet Metal Fabrication?
Sheet metal fabrication is defined as the processes to turn flat metallic sheets into useful products. Various special tools are used in this process to convert sheet metals into useful components by minimal efforts. It is a value-added process to create machines, structures, or component parts following engineering drawings which usually serves as the instruction sheet to produce a finished product from the base metal.
Types of Sheet Metal Fabrication Materials
There are many different types of sheet metals available that are suitable for various fabrication processes. The choice of metal depends on the final use of the fabricated parts. Common metals and alloys that are widely used for sheet metal fabrication process are:
- Carbon Steel
- Stainless Steel
Steps involved in Sheet Metal Fabrication Process
The steps that usually are followed in sheet metal fabrication job are:
- Working with blueprints– The first step in metal fabrication process is to create the blueprints to determine the sheet metal product specifications for making rough drawings.
- Creating a final shop drawing– Final engineering drawings are then prepared after rounds of checking of the rough drawings and calculations. It is ensured that the final product meets all necessary specifications and requirements. The final drawings includes in-depth calculations of sheet metal stress levels and load limitations to determine the steps of the fabrication process.
- The metal fabrication process– The sheet metal fabrication process involves cutting, bending, welding, forming, joining, and finishing.
- Product finishing– After fabrication of the component is complete, a product has to undergo the product finishing steps like sand blasting, brushing, polishing, powder coating, plating, etc. After this step, the product will be ready for commercial use.
Types of Metal Fabrication Processes
The journey to final product from raw sheet metals proceeds through various sheet metal fabrication processes. All the sheet metal fabrication processes can be grouped into the following three categories:
Sheet metal fabrication: Cutting
The most widely and frequently used sheet metal fabrication process is cutting. Variety of different types of machineries are used to cut sheet metal to manipulate it for making a component. They are:
Laser Cutting: Laser cutting is a very quick, energy-efficient, and precise sheet metal cutting process which uses a powerful laser to cut thin or medium gauges of sheet metals.
Water Jet Cutting: In water jet cutting, a high-pressure jet of water with abrasive substances is used to cut the sheet metals. As water jet cutting does not generate heat in the process, this sheet metal fabrication process is particularly useful for metals having low melting points to avoid deformation due to heat generation.
Plasma Cutting: Plasma cutting is used for thicker sheet metals. In this metal fabrication process, a jet of hot plasma is used to penetrate the metal sheets. This method is highly powerful having low set up costs, however, less accurate than laser cutting or water jet cutting.
The comparison between Laser cutting, Water jet cutting, and Plasma cutting is provided in Table 1 below:
|Sheet Metal Cutting Process||Laser Cutting||Water Jet Cutting||Plasma Cutting|
|Advantages||Wider range of materials.|
Depth control functionality can engrave and part mark.
Negligible residual burrs.
Low surface roughness.
No Heat Generation.
Wide range of materials.
Suitable for thicker sheet metals.
|Disadvantages||Heat distorsion may occur.|
Possibilities of HAZ formation.
Not suitable for thicker gauge sheet metals.
|Less precise than laser cutting.|
Not suitable for part marking or engraving.
|Produces rough cut with large burr.|
Limited to electrically conductive materials only.
Punching or Piercing: In this method, a punch and die cut precise holes in sheet metals. The sheet metal is placed between those two components and the metal punch perforates the sheet to remove circular pieces which can be used as new work pieces known as blanking. For large scale production, punching is an effective process but not cost-effective for smaller jobs.
Sawing: Different types of sawing operation can be performed to cut softer sheet metals.
Machining: In this process, sheet metals are cut using tools like a drill bit or lathe blade.
Sheet metal fabrication: Forming or Deformation
Deformation is the next major method for sheet metal fabrication processes. In this process, the sheet metal is manipulated or shaped without cutting it. Widely used sheet metal deformation processes are:
Bending: Sheet metal bending is one of the most popular deformation process. A machine known as Press brake, is used to bend sheet metals into V,U, or other complex shapes. With an increase in gauge thicknesses of sheet metals the force required to bend increases. The process of removing the bends from sheet metal is known as decambering.
Stamping: In the stamping process, a hydraulic or mechanical stamping press equipped with a tool and die is used to perform specific tasks like curling, drawing, embossing, flanging, etc.
Hemming: Hemming is a process by which the edges of a sheet metal are folded over itself or another piece of sheet metal to create rounded edge. In sheet metal fabrication process two types of hemming processes are widely involved. They are roll hemming and conventional die hemming. Conventional hemming is used for mass production. A hemming roller is used for roll hemming.
Spinning: Spinning is a metal fabrication process where a lathe machine is used to rotate the sheet metal against a tool to produce conical or cylindrical shapes.
Other sheet metal deformation processes include rolling and wheeling. Rolling involves the use of a pair of rollers to reduce its thickness whereas wheeling produces compound curves in sheet metals.
Sheet metal fabrication: Assembly
Assembly is basically joining sheet metal components produced using above mentioned cutting or bending processes. Common sheet metal assembly process consist of joining by Welding and joining using fasteners.
Welding: In the welding process, sheet metal components are joined together by melting sections with the application of heat to form a solid connection. There are various processes available that are used to weld sheet metals.
Joining using Fasteners: Similar or dissimilar sheet metal parts can easily be joined using fasteners like bolts, screws, rivets, etc.
Brazing: Brazing is a process similar to welding that operates by melting a filler without melting the sheet metals.
Adhesives: Adhesives can be used to hold metal sheets together in conjunction with other joining methods.
Applications of Sheet Metal Fabrication Process
Sheet metal is considered as one of the most versatile materials and processes in the world today. Numerous large and small components are developed by designers and engineers. Sheet metal fabrication processes are used in every industries including:
- Refrigerators, freezers, and other home appliances
- Airplane components
- Automobile parts and Chassis
- Metal sinks
- Consumer goods industry
- Electrical enclosures
- lockers, furniture, and Cabinets
- HVAC industry
- Steel shades and garages
- Electronics and robotics industry
- Stainless steel kitchen accessories, surgical instruments, tanks, vales, piping
- Construction industry
- Energy Sector
- Aluminum sheet metals in phones, laptops, light casings
Advantages and Disadvantages of Sheet Metal Fabrication
As sheet metal fabrication covers a wide area of techniques and methods, the advantages and limitations will vary depending on the process used during fabrication. The general benefits are:
- Sheet metal fabrication is fast and can produce high-quality components.
- A large number of processes are available with wide range of materials.
- High strength to weight ratio for sheet metal fabricated parts.
The main disadvantages of sheet metal fabrication process are
- Each fabrication process has their own limitations.
- High initial cost for set up of equipment and tools.
- Requirement of skilled labours for each processes