Sheet Metal Fabrication: Everything You Need to Know
Before picking a new manufacturing process, it is crucial to understand the basics of sheet metal fabrication technology. That means you must become familiar with what it is, how it works, and its benefits. In this article, we go over the basics of sheet metal fabrication. We aim to share our knowledge of sheet metal fabrication technology and its many applications in many industries.
What is Sheet Metal Fabrication?
Sheet metal fabrication is the action of transforming flat sheets into usable forms. With that in mind, it is helpful to think of this metal forming process as a series of forming techniques rather than a single manufacturing process.
Differing sheet metal fabrication strategies often work in concert with each other to produce the necessary parts. Sheet metal fabrication processes include bending, punching, cutting, stamping, welding, and finishing. More details on these techniques will be covered further in this article.
Sheet metal fabrication can utilize many metal materials. Sheet metal parts are often aluminum, steel, stainless steel, copper, and brass. These metal products are so prevalent that you cannot go through a day without encountering the result of sheet metal fabrication. These products are everywhere, whether in your home or on the streets.
What is the Sheet Metal Design Process?
Most people don’t understand the basic steps involved in sheet metal manufacturing. Not knowing the fabrication process can result in unrealistic requirements and expectations for a project. Sheet metal working methods often involve a multi-step process that requires many skilled professionals and tools to complete the job successfully.
From beginning to end, the metal fabrication design process includes the following:
Every rapid prototype begins with an idea, and sheet metal projects are no exception. It starts with basic concepts of what you want as a designer. You can put these ideas down roughly to provide realistic requirements for your project. It may also involve designing a 3D model of the desired sheet metal component. The model often includes requirements for wall thickness, bend radii, hole orientation, bend allowance, and more.
Engineering & Design
After completing a 3D model, there is a need to create drawings for manufacturing. Before any work can begin, engineers need to develop blueprints to determine the sheet metal specifications required to make initial drawings.
The drawings are what gets sent to the fab shop. The drawings often include all manufacturing information, such as material selection, surface finishing, and more.
The drawings get reviewed along with other related calculations to ensure they follow requirements and specifications. Following lean manufacturing strategy simplifies the designs and reduces part counts, and such analysis suggests standardizing parts for various applications.
Additionally, engineers will get insights into developing designs that can be more easily manufactured. When the manufacturability review is complete, there will be a final shop drawing with in-depth stress/strain levels and load limitations specifications. The drawings will also aid in determining the sheet metal fabrication process.
Once there is an engineered and reviewed design, specialists carry out several processes to maintain the part’s geometry. These methods include cutting, bending, punching, stamping, and welding. Surface finishes also help to improve the final look of the created prototype. It is essential to carry out these steps in order. Rushing through the process or skipping one step may compromise the quality and integrity of the final product.
After developing the prototype, clients and quality control evaluate the product to ensure it meets their requirements. The testing may also involve using real-life conditions.
A prototype that passes testing and meets the required specification will go into total part production.
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Sheet Metal Fabrication Techniques
When considering sheet metal fabrication, it is imperative to know the techniques used. These sheet metal processing methods help to transform flat sheets of metal into three-dimensional, functional components. Below are the most common sheet metal processing techniques.
Cutting is most often the first step in sheet metal manufacturing. As you can probably guess, it consists of cutting the metal sheet. Manufacturers start with a rectangular metal sheet and cut the material to size.
With that said, There are various methods for cutting sheet metals. These cutting methods are shearing, punching, blanking, and laser cutting. Using sheers involves using force and an edge to cut through the metal.
At ATRON, we most often use sheet metal laser cutting, a shear-less process. We consider this process most suited for industrial applications. Laser cutting enables high precision (+/- 0.1 mm) and is time-efficient. We also offer plasma and punch cutting, which also provide high-precision cutting.
Stamping is a cold-forming method that transforms flat metal blanks into various shapes. The process uses a tool and die, which, when impacted, changes the form of the metal through pressure.
Stamping is a broad term within sheet metal manufacturing. It encompasses punching, bending, as well as embossing. It also incorporates flanging, which entails swiping the sheet of metal in such a way as to form flanges.
Bending is another common step in sheet metal fabrication. It consists of bending the metal sheets. Metal fabricators carry out sheet metal bending using press brakes, rolling machines, and other equipment. The sets of equipment create standard shapes such as U-bends or V-bends.
Regardless of how simple bending may seem to the average person, it is a complex process that requires highly skilled technicians. Mainly due to how metal behaves when bent. When metal is bent, it wants to bounce back to its original form, called “spring back.” To overcome this sheet metal fabrication problem, technicians must overbend the part so that its spring-back angle is the desired angle.
Punching is a technique used to create holes in a metal sheet. The method relies on a punch and die (often made from a hard metal). The materials use force to perforate holes into the metal sheet, and the die then collects the scrap material created from the spot. Punching also helps to make an indentation in the metal sheet. ATRON’s CNC punching capability can create holes up to 50 mm.
Welding is one of the final stages of sheet metal fabrication, and it is a
fundamental sheet metal process for joining metal pieces into a single part. Many welding techniques are available, including stick welding, MIG, and TIG.
All three methods have the function of joining metal together by melting the edge of the part and adding filler, creating a metallurgical bond between the pieces and strongly fusing them. Welding is only necessary, of course, if a product comes with two or more separate components.
Metals to Choose From
There is a wide range of materials used in sheet metal engineering. Making the best choice for your product is vital to ensure optimal quality. Your choice should depend on your desired end product and overall expectations. Here are some of the sheet metal materials used in fabrication:
There are several stainless steel types. They can be austenitic stainless steel. These are non-magnetic metals with high nickel and chromium levels. Most often used due to their resistance to corrosion and formability. Ferritic stainless, on the other hand, is magnetic and suitable for non-structural or decorative applications. Martensitic stainless also give strong and corrosion-resistant products.
Hot Rolled Steel
A type of steel produced when a series of roll processes (at over 1700 degrees Fahrenheit) create steel. You can quickly form such steel into large pieces due to its flexibility.
Cold Rolled Steel
This is essentially hot-rolled steel with further processing, and they are smoother and come with better tolerances.
These are also referred to as galvanized sheet metal materials. They come with a protective coating to prevent rust and support easy sheet metal processing methods due to increased flexibility.
Another popular choice for the manufacturing sector. It comes with an excellent strength-to-weight ratio, and it also comes with many characteristics that help it meet many application requirements.
Working on brass is easy, thanks to its lower zinc content. Copper metals also come with protective oxide layers to prevent corrosion. Both materials are desirable in architectural products for aesthetically pleasing looks.
Surface finishing is another typical process of custom sheet metal fabrication. The metal surface finishes have both aesthetic and functional benefits.
Some of the surface finishes you can apply on sheet metal are:
This method involves high-speed shooting sand or other abrasives against sheet metal. Thus, it gives the sheet metal a matte texture to prepare it for coating.
In this method, a cloth wheel buffs the metal surface, making it look shiny.
This involves directly spraying powdered paint onto the metal part. This is followed by baking the component in an oven to form a wear-resistant layer.
Anodizing helps to give a component with excellent rust resistance properties, and it also improves the hardness and durability of the surface.
These are finishes that provide good conductivity and corrosion resistance. This coating process best serves as a base for paint and gives a golden surface finish.
Here are some design elements to consider when modeling a sheet metal part:
Uniform thickness is significant for any geometry. Geometries with more than one wall thickness will require sheet metals of different thicknesses. Therefore, the alignment and orientation of parts may be inaccurate or take time.
Keeping the inside bend radius of sheet metal equal to its thickness is vital, and this will help to avoid distortions and fractions in the final parts. Maintaining the bend radii consistently across the region ensures cost-effectiveness and good orientation.
Bend Allowance and Deduction:
The material needed to be added to the actual lengths of the parts to help develop a flat pattern. Bend deduction is the required material to be removed from the height of the flanges to help get a balanced design.
K factor is the sheet metal process ratio of neutral axis to material thickness. This value changes concerning the various physical properties and thicknesses of materials used.
Holes and Slots Orientation:
These factors are also critical. Holes and slots’ diameter should at least be as large as the thickness of the sheet metal. Also, holes should be reasonably spaced and should never be too close to the edge of the material.
Other features are hems, notches, tabs, curls, fillets, and countersinks.
Sheet Metal Tips
It is essential to note some practical sheet metal fabrication design tips for better efficiency when creating components.
Specifying hole sizes, alignment, and locations in a sheet metal design is vital. Hole diameters lesser than the thickness of sheet metal may result in long burnish, high punch loading, and excessive burr. Therefore, hole diameters should be greater than the sheet metal’s thickness.
Also, the distance between holes should be at least twice the sheet metal thickness. In cases where a cut-out must be near the edge, spacing between the hole and the border should be at least the sheet thickness.
Collars and bend relief near pierce areas help to strengthen sheet metal parts. Grain structures are also essential to avoid cracks in parts with tabs or lugs. Lugs should not be parallel to the grain direction, leading to cracks forming. Instead, they should be perpendicular or slightly less than 45 degrees towards the grain direction.
Keep the punch-to-die clearances large to avoid premature wearing out of the punch. You tend to increase stiffness by putting beads on bends and chamfers at corners. This way, you can reduce the spring-back effect. A sheet metal part can easily maintain its flatness and strength by coining around flared holes.
Why Choose ATRON's Sheet Metal Fabrication
ATRON’s technical sales team, mechanical designers, and machine operators excel at helping you produce your sheet metal Project. We can do it whether it’s structural/architectural metal work, machine refurbishing, or prototyping projects.
Whether it is a simple component or a complex automated machine, our precision metal fabrication and design services are capable of taking your project from idea to reality.
We provide a complete package of services by following industry standards and using top-of-the-line software (AutoDesk, SolidWorks, CAD) and equipment. We will produce solid models, a complete drawing package, proof of concept pieces, or your finished product.
ATRON has almost 30 years of experience in Engineering & Design, Laser Cutting, CNC Punching, Forming & Rolling, Welding, Finishing, Assembly, and more. Let us know how our team can assist you.