What is sheet metal fabrication?
What is Sheet Metal fabrication and what are the processes behind it?
In this article we provide a useful overview of what sheet metal fabrication is, what it is used for, some of the processes and the machinery and tools involved in producing the end product.
What is sheet metal?
As its name implies, sheet metal is metal material that has been worked into a thin, flat sheet for the purposes of further manufacture and finishing. The thickness of sheet metal ranges from 0.5mm up to 6mm, anything over that thickness being classified as metal plate.
There are several stages involved in sheet metal fabrication, which is the broad term for the journey from a piece of sheet metal to a finished item. A combination of any number of the following processes might be involved in a specific sheet metal fabrication project.
What is involved in the sheet metal fabrication process?
Design
Any fabrication project needs to start with a detailed design for the engineers to work from. At F-Tech we can work with clients’ designs or engineer our own designs from an initial proposal or by reverse engineering an existing component. Modern sheet metal fabrication uses highly advanced CAD software to create detailed and precise drawings which can then be used to programme automated equipment.
Programming
For the fabrication to take place, the designs – often in the form of complex drawings – must be turned into instructions that the computers operating the various automated tools can follow. This transformation marks the programming stage of the process
Cutting
Laser cutting is used in modern sheet metal fabrication. The heat of the laser produces an extremely clean cut through the sheet metal, with a reliably smooth edge. Computer numerical controlled (CNC) laser cutters are automated and can be used to cut highly complex shapes with complete precision multiple times.
Punching
Punching is a technique that involves a specially shaped head being brought into contact with the surface of the metal and either cutting through to leave a hole or pressing a specific shape into the surface. CNC punching can be used to punch multiple impressions into a single component at speed and with total accuracy.
Bending (CNC Folding)
CNC folding – the term generally used for bending a piece of sheet metal as detailed in a design – is performed using a range of machines including an automated panel bending machine, although manual press braking might still be used for highly specialised applications. CNC folding can deliver extremely precise folds in a piece of sheet metal along multiple axes, using specialist tools to create highly specific curves.
Welding
A common aspect of sheet metal fabrication, modern sheet metal fabrication specialists use MIG welding, TIG welding and spot welding as well as robotic welding in which the arm delivering the weld is controlled by CNC programming.
Assembly
The complexity of the assembly of a sheet metal fabrication project will vary depending on the size and purpose of the component itself and the number of different processes involved. Sheet metal assembly could involve joining several separate sheet metal components to form a more complex final component, or it could mean assembling sheet metal parts onto other parts.
Finishing
Many sheet metal components need to have a specialised coating applied for protection, aesthetic appeal or branding.
- Powder coating involves electrostatic powder being applied to the metal surface followed by heat bonding for a durable finish.
- Wet spray finishing is used to apply paint to a metal component to an even thickness of approximately 15 to 20 micrometres.
- Linishing and fettling is a specialised skill that makes welds impenetrable, producing a finish that prepares the part for a surface treatment.
- Screen printing uses a mesh to transfer ink onto the metal via a blocking stencil to create an image or pattern.
- SurTec 650 is a passivation process based on non-toxic trivalent chromium used to provide a corrosion-resistant finish before painting.
- Anodizing is an electrochemical finishing process used to apply a decorative, durable, corrosion-resistant and anodic oxide finish to the metal.
What tools are involved in the delivery of sheet metal fabrication?
Many tools are used in the delivery of deliver sheet metal projects.
CAD design software
This is the highly specialised software that enables designers to create detailed 3D drawings. CAD files are output for use by the complex machines (such as CNC mills and lathes) used in manufacturing.
Prototyping technology
Creating a prototype may be one of the most important parts of a sheet metal fabrication project, particularly if the finished component needs to be produced in large numbers. The term ‘prototyping technology’ may cover specialist machines such as CNC machines but could also include welding or laser cutting technology. The prototype helps engineers establish proof of concept, iron out any design or functional issues, and prove the design for efficiency before full-scale manufacturing begins.
Laser cutters
State of the art laser cutters can be programmed using CAD software to cut highly complex shapes through sheet metal with complete precision. The automated nature of laser cutters offers two huge advantages. First, the same precise cut can be repeated multiple times. Secondly, the machine can be programmed to work round the clock to meet tight deadlines.
Laser / punch combination
A laser punch combination set-up can be used to deliver fabrication work which requires a combination of laser cutting through the sheet metal and the punching of holes or forms. The advantage of using a combined machine is that it can be programmed to deliver both aspects of the work on each sheet of metal, rather than two separate machines having to be programmed and the material needing to be shifted mid-fabrication.
CNC punch machinery
The process of punching holes or shapes into a piece of sheet metal has been explained above. CNC punch machines deliver this work using computer programming to control the punching head and deliver multiple holes or forms at speed and with complete accuracy.
Folding machinery
Folding and bending are key processes utilised when working with sheet metal to create 3D forms. A modern sheet metal fabrication service will offer a range of machines, from manual press brakes to automated robotic folders, which means being able to deliver projects of any size and specification. An automated folding machine can deliver folds along multiple axes at speed and with complete accuracy, creating complex shapes for large scale production runs.
Robotic welders
The process of welding has been set out above, and robotic welding refers to the use of an automated arm to deliver the actual welds. The arm can be programmed from CAD designs to deliver highly complex weld lines which can be repeated multiple times with no drop in quality or precision.
Finishing plant
Depending on the type of finish required, different technologies and equipment are required to complete the finishing process.
For example, powder coating plant is a self-contained area and set of equipment within a sheet metal fabrication production line in which the powder coating is delivered. Once the plant has been installed, individual powder coating jobs can be automated and delivered with maximum efficiency.
CMM technology
CMM technology refers to coordinate measuring machine technology. It is a device used to measure the physical dimensions of a three-dimensional object along all three axes and can be either hand-controlled or automated.
Materials used in sheet metal fabrication
The materials commonly used for sheet metal fabrication include aluminium, mild steel and stainless steel.
About F-Tech Precision Engineering
F-Tech offers a complete in-house sheet metal fabrication service, which means we can take clients from initial consultation, through design and prototyping and on to manufacture.
To learn more about our sheet metal fabrication services view our sheet metal capabilities or contact our specialist team would be happy to listen to your requirements and explain exactly what we could do for you.
