One of the cornerstones of modern engineering is sheet metal fabrication, this method of manufacturing has a key role in the creation of a wide variety of products and industries. The process involves converting flat sheets of metal into complex and useful components through cutting, bending and assembling.
The flexibility and strength of sheet metal make it an indispensable material and process in engineering, shaping the landscape of manufacture and design. In this article, we explore the foundations of sheet metal fabrication and manufacturing and the following key areas:
- Its varied applications
- Key equipment involved
- The importance of precision
- Sustainable practices
- Its role in rapid prototyping and rapid manufacturing
The Basics of Sheet Metal Fabrication
Understanding the Raw Material
Sheet Metal Fabrication begins with specifying the most suitable material to be used for the component’s intended application, this includes material type and thickness (gauge). Sheet metal comes in various materials the most common being Aluminium, Steel, Galvanized Steel, Stainless Steel, Copper and Brass. These materials come in a variety of thicknesses from 0.3-6mm. The choice of material will depend on a variety of factors, such as the intended application, structural requirements and cost considerations. The characteristics of each metal must be understood and crucial in ensuring the final product meets the specifications.
Types of Sheet Metals Their Properties and Characteristics
Different sheet metal materials process unique and differing performance characteristics that influence the applications in which they are used. When making the materials selection for a component or product these characteristics must be considered carefully. For example, steel is known for its strength and durability and is used widely within the construction and automotive industry. Aluminium is prized for being lightweight and having high levels of corrosion resistance and finds extensive use within the aerospace and consumer goods sectors. Stainless Steel is valued for its high levels of corrosion resistance in harsh environments and is commonly used in the marine and industrial chemical processing sectors.
Sheet Metal in Engineering
Applications Across Industries
Sheet Metal fabrication is widespread across several industries, due to its adaptability and versatile nature. From aerospace, automotive, construction and electronics the applications are virtually unlimited. The ability to form, bend and mould sheet metal into intricate shapes and designs, makes it an ideal choice for forming components ranging from simple brackets to complex structural elements. Below we have a further look at how the automotive and aerospace sectors utilise this process.
Automotive Sector: Transforming the Road
The automotive sector heavily relies on sheet metal for a number of elements within vehicle production. The chassis, body panels and engine bay brackets are the most obvious examples of this. Sheet metal is chosen due to its formability, strength and cost effectiveness, ensuring the precision of these components during fabrication helps ensure the safety, performance and aesthetic appeal of vehicles.
The chassis provides the structural platform within a vehicle, supporting the weight of the vehicle and serving as a platform for attaching other components. The use of sheet metal within the chassis is driven by the combination of strength and formability. During normal operation, the materials’ strength, design and formed shape optimise the structural integrity and weight efficiency of the vehicle.
The outer skin of an automobile comprises mostly of painted steel body panels and is bend of aesthetics and functionality. The sheet metal’s formability is once again a key factor in choosing this process for manufacturing the body work. This allows the designers to define sleek and aerodynamic shapes of modern vehicles providing an aesthetically pleasing object while providing an effective barrier to the external elements for the passengers.
A clear example of how a car door is formed and assembled can be found in this YouTube video.
Aerospace Advancements: Soaring with Sheet Metal
The aerospace industry, where weight and mass are critical factors in design and operations leads to aluminium being an obvious choice in manufacture. From aircraft frames, engine components and bodywork sheet metal fabrication in aluminium has become the norm. This has helped to advance the development of high performance, efficient and safe aerospace systems and aircraft.
At the core of every aircraft is an airframe similar to a vehicle chassis this frame withstands the stresses of take-off, landing and flight. Within the aerospace industry weight is everything, and sheet metal’s ability to provide both strength and lightness is advantageous for components within the airframe. allowing designers to strike a balance between structural integrity and fuel efficiency to achieve an optimal design.
Equipment in Sheet Metal Fabrication
Laser Cutting for Precision
Laser cutting has revolutionised sheet metal fabrication, by offering speed, precision and complexity for the components to be manufactured. A high powered laser is used to precisely cut through the metal, allowing for intricate designs and complex shapes to be cut. This technology also reduces waste by allowing the nesting of parts within the sheet of metal, reducing wastage and increasing efficiency.
Forming with Accuracy
Typically most sheet metal fabrication components or products have a forming element to them, whether that be folding, bending, press forming or stamping as demonstrated in the car door video. Typically if bending or folding are required then a press bake is used to create the desired fold to the correct angle, the press brake is capable of performing straight uniform folds into the metal. Press forming and stamping requires the manufacture of a male and female die for the component being created, and allow the flat sheet to be pressed into the desired shape. This type of manufacture lends itself to mass production due to the cost of manufacturing the dies.
The Importance of CAD is Sheet Metal Design
Computer Aided Design (CAD) software plays a pivotal role in sheet metal fabrication. Design engineers use CAD software such as SolidWorks to create detailed and accurate 3D models and 2D Drawings facilitating the seamless transition from concept to reality. When the components are designed using CAD clash detection can take place as well as developing the net shape and calculating for the bend radii of the component.
Finally CAD can be taken one step further to accurately nest parts for laser cutting making the best use of the entire sheet and reducing wastage. Further modern press brake machines can be programmed from the 3D model to carry out the folding of the parts, reducing human error, waste and increasing efficiency.
Balancing Aesthetics with Structural Integrity
When it comes to sheet metal fabrication, the structural integrity of the component can not be undermined by the aesthetics of the product. These elements must strike a balance with each other, there is little to no point in having a component that looks good but is not strong enough to do the job. The best real world example of the confluence of these elements is automotive bodywork.
The creases and lines in the sheet metal don’t just make the vehicle look good, adding to the overall appeal of the product to customers; they also significantly increase the strength of the sheet metal making the product more robust in everyday use.
Precision in Sheet Metal Manufacturing
Tolerance and Quality Control
Achieving precision in sheet metal fabrication has traditionally been a difficult task to complete. This has been simplified by the use of modern machinery such as laser cutters and Computer Numerically Controlled (CNC) press brakes, as these have a higher degree of accuracy than traditional machinery.
Meticulous attention must be paid to the tolerances of both the machines and components to get the best results. Tolerances dictate the permissible variations in the dimensions of a component ensuring the component will perform as specified. As well as manufacturing the components each batch needs to be checked against the technical drawing of the part to ensure the components are being manufactured correctly and that the machine limits have not slipped due to wear.
Quality Assurance Measures
Stringent quality assurance measures are integral to delivering a quality component and product when performing sheet metal fabrication. There are several steps that need to be performed along the way:
- Material inspection
- Dimensional check of blanks before forming
- Post fabrication dimension checks
- Post fabrication testing
To ensure components are being delivered that conform to the customer’s specifications these checks will be routinely carried out. Depending on batch component quantity size 10 in 100 or 1 in 1000 will be checked to ensure conformity.
As the world increasingly embraces sustainable practices, the manufacturing sector, including sheet metal fabrication must look to become more sustainable also. Engineers must look to optimise the design of their products and components to ensure these can be made as efficiently as possible, as well as reducing the environmental impact which can drastically reduce the cost. Simple ways of reducing the environmental impact of sheet metal fabrication include:
- Component reduction is products
- Efficient nesting of similar blanks within the sheet
- Using simulation tools within CAD to optimise the design of components
- Recycling sheet metal scraps and waste
Rapid prototyping and Rapid Manufacturing
Accelerating Product Development
This manufacturing process can be used to significantly accelerate product development cycles. The ability to rapidly develop a 3D model to a physical prototype, allows engineers to iterate and test quickly. This reduces the overall time to market and provides agility to sectors sensitive to innovation and responsive market demand.
The rapid prototyping of sheet metal components allows engineers to validate the design before full scale production commences. This enables higher quality products to be delivered to customers.
Sheet Metals Roles in Just-in-Time Manufacturing
Just-in-Time (JIT) manufacturing, is a philosophy aimed at minimising the inventory and production costs of components within the assembly of products. Sheet metal fabrication aligns well with this idea as components can be made to the demand of the wider supply chain or assembly line for a product.
The added benefit of streamlining this process with the supply chain or assembly lines includes reducing waste and improving energy efficiency. Sectors that rely heavily on this method such as the automotive, aerospace and construction sectors have proved this work time and again, providing consumers with cheaper products more efficiently.
In conclusion, sheet metal fabrication stands as a pillar of modern engineering, contributing to the manufacture of diverse products across many industries. From the basics of understanding the raw materials to precise manufacturing using sustainable practices, sheet metal’s versatility makes it an indispensable player in the dynamic world of engineering and manufacturing. As technology continues to advance, sheet metal will continue to play a prominent role in shaping the world of tomorrow.