Sheet metal fabrication is a crucial process in the manufacturing industry, with numerous applications in construction, automotive, aerospace, and other fields. The versatility of sheet metal and its ability to be formed into various shapes and sizes make it a popular choice for creating complex and intricate designs.
However, to ensure the success of any sheet metal fabrication project, it is essential to have a solid understanding of the design principles and best practices. In this article, we will provide a comprehensive guide to sheet metal fabrication design, including tips for material selection, geometric constraints, and cost-effective design strategies.
Whether you&#;re a seasoned engineer or a novice designer, this guide will help you create high-quality sheet metal parts that meet your project&#;s requirements and specifications.
For manufacturing purposes, sheet metal is classified as anything thinner than 0.25 inches. All sheet metal parts come with the requirement of having consistent width, which limits some of its applications. But ensures that the resulting part is able to fulfill the requirements of durability and longevity.
Generally, sheet metal parts are common in applications like automobile chassis and other areas where the strength-to-weight ratio is important. Sheet metal has a lower thickness and parts made of it are generally hollow. This means that they&#;ll weigh less but will have the same capacity to sustain greater loads.
There is no point in opting for precision processes for simple applications. However, avoiding precision sheet metal fabrication for high-value applications is also not feasible. Because it may cause damage to sensitive equipment due to wear and tear.
The working principle behind sheet metal fabrication is quite simple. It depends on the elasticity of the metal and the fact that cold-rolled metal performs better in terms of durability. Sheet metal fabrication consists of two methods, cutting and forming.
As its name suggests, cutting requires removing a part of the sheet to obtain the desired shape. On the other hand, forming is a bit difficult method consisting of three different processes. They mostly work together to create the form of the object you need. The process requires careful consideration of the design and manufacturability to minimize any waste and ensure perfection.
In most cases, manufacturers rely on CAD files in either the DXF or DWG model to ensure compliance with the available design. In most projects, the cutting and forming processes work in tandem as it allows for quicker results. Moreover, sheet metal fabrication generally requires no post-processing but may need some finishing and joining depending on the application.
The sheet metal fabrication process consists of two main processes; forming and cutting. These two techniques work together to create the final form of any product. While cutting is a simple process, forming has further classifications, namely stamping, bending, and punching.
Here are the basic details related to the main techniques for creating sheet metal parts:
The cutting process removes the excess sheet metal in a particular shape to obtain the final form. There are 3 main approaches when it comes to cutting sheet metal:
The bending process simply applies a great force on the sheet metal at a specific point to obtain the required shape. In some cases, the area under the bend might need some preparation. For instance, bend notches not only show the technician the location of the bend but can also facilitate the process itself.
To create a complex part in a limited time, manufacturers often select the stamping process, which is a complex form of form. The process uses a combination of different techniques using shearing, bending, and stretching to create new shapes out of sheet metal.
To create a complex part in a limited time, manufacturers often select the stamping process, which is a complex form of form. The process uses a combination of different techniques including shearing, bending, and stretching to create new shapes out of sheet metal. Furthermore, some stamping processes even go as far as joining multiple pieces using different techniques as well.
Sheet metal parts designs are quite popular in many industries because of their perceived advantages. However, there are multiple limitations to the process as well. These advantages and limitations are among the most important design considerations for manufacturers as they determine the correct applications of the metal.
AdvantagesDisadvantagesQuick turnaround when compared to other manufacturing methods.Difficult to make complex designs with intricate details, which can limit the range of shapes and forms that can be produced.High-quality parts for both production and prototyping. Requires significant investment for tooling and other equipment, which can be a barrier to small-scale production. Versatile enough to work with several metals, such as steel, aluminum, and copper. Have longer lead times compared to other fabrication methods due to the multiple stages involved in the process, such as cutting, forming, and finishing.Delivers a high strength-to-weight ratio because of the hollow design. Requires skilled labor, which can be expensive Needs no post-processing in most cases.As stated before, the design for sheet metal fabrication needs attention to some design requirements. Most of those requirements depend on the overall design of the product. For instance, a simple product would not have many requirements but an intricate geometry would naturally need more processes to be market-ready.
Generally, sheet metal fabrication requires a series of best practices that can ensure perfection and deliver the best quality in the shortest time. The general guidelines for sheet metals include the following 5 categories.
Tolerance is one of the most important parameters for a variety of applications. The general rule of thumb states that more precision requires more resources and has additional costs. So, the tolerances should be according to the application.
The perfect example of this can be the automobile industry.
The precision required for the door or any other part of the body would obviously be lower than the requirement for the chassis or some other integral part. Generally, tolerance requirements depend on the project requirements but that approach can have a lot of inconsistencies in the product.
Many manufacturers and industries prefer to set quality standards to avoid those inconsistencies. While these standards are not a one-size-fits-all solution, they are an excellent tool for maintaining consistency and performance. Furthermore, compliance with industry standards also makes it easier to fulfill industrial requirements and build consumers&#; trust in the brand.
For sheet metal fabrication, the prevalent standard is ISO . This covers the tolerance requirements for multiple industries while maintaining the perfect balance between costs and processing capabilities.
For sheet metal fabrication, there are a few general tolerances that the industry uses everywhere. They are in compliance with international standards. However, there will be several exceptions to them in the case of sensitive applications like aerospace and automobile where precision is critical for performance.
General Tolerances of Sheet Metal FabricationFeaturePrevalent Tolerance RangeAdditional NotesWall thickness0.9mm to 20mm Offsets0.3mm to 0.7mm Curls>2x material thicknessAnything less than the recommended curl dimension would make the sheet brittle.Bends0.9mm &#; 1.2mm1.8mm &#; 2.4mm3.8mm &#; 5.0mm7.5mm &#; 10mm15mm &#; 20mmA +/- degree deviation is expected on all bends. Moreover, any other specifications will add to your costs.HemsInside dia = material thickness with return length to be 4x the thickness CountersinksMajor dia = +/- 0,254 mmMinor dia > 2/3 thickness Holes and slotsDia > material thicknessA diameter less than the material thickness would cause cracks in the sheet.Notches and tabsNotch width > 1.5x thicknessIn this process, a flat sheet of metal is bent into a predetermined form by applying pressure. The process requirements and details change according to the type of bending process. While there are numerous ways, the following three methods of sheet metal bending are the most common.
When it comes to the bending process, there are multiple parameters that manufacturers and designers must consider. These design requirements are what fundamentally characterize any sheet metal bend and it&#;s advisable to adhere to their standards to ensure excellent results.
Here are the 6 most important parameters for any sheet metal bending operation.
Another important process in sheet metal fabrication is cutting. In many cases, it&#;s an easier alternative that delivers fast results with acceptable precision. During the design phase, sheet metal design guidelines focus on the following 5 parameters.
During the process, the material characteristics play an important role in determining the suitable process for the specific material. Consider the example of Aluminum and Steel to understand this better. Naturally, cutting Aluminum would be simpler than dealing with steel because of steel&#;s relative strength and durability.
For material selection, the best practice is to consider manufacturability as well. For instance, if both steel and aluminum can sustain loads of a particular operation, it&#;s not always smarter to go for the stronger alternative (steel) without considering the manufacturing capabilities.
When designing a product that involves drilling holes in a sheet, it is important to consider the thickness of the sheet and the diameter of the hole. A general rule of thumb is to ensure the diameter of the hole is at least equal to the overall thickness of the sheet.
If the diameter of the hole is too small in comparison to the thickness of the sheet, it can result in the formation of cracks and brittle areas around the hole. These cracks can propagate over time and lead to durability issues that can negatively impact the overall performance of the product.
Therefore, it is important to make sure the diameter of the hole is appropriate for the thickness of the sheet in order to maintain the structural integrity and long-term durability of the product.
When materials are cut, the process can generate significant amounts of heat, which can have an impact on their properties. Specifically, the region surrounding the cut may become overheated, leading to localized hardening. To prevent this problem, it is recommended to slow down the cutting speed overall and to use coolants to regulate the temperature in the affected area. By doing so, the risk of localized hardening can be minimized.
Distortion in sheet metal fabrication refers to the warping, bending, twisting, or buckling of the metal sheet during the manufacturing process. This issue can occur due to a variety of factors, such as changes in temperature, stress, or pressure during the fabrication process. Distortion can cause significant problems in the final product, such as dimensional inaccuracies, poor fitment, and reduced strength.
The kerf is directly related to the width of the cutting tool used and the thickness of the material being cut. Essentially, it represents the width of the material that is removed by the cutting tool, and it determines how much material is wasted in the cutting process.
For example, if a laser beam has a kerf of 0.1mm, and a cut is made through a sheet of metal that is 1mm thick, then the total width of material removed from the sheet will be 0.2mm (0.1mm from each side of the cut). The kerf width may vary depending on the type of cutting process, the type of material being cut, and the thickness of the material.
It&#;s important to consider the kerf when designing parts for sheet metal fabrication, as it can affect the final dimensions of the part. If precise dimensions are required, then the designer should take the kerf into account and adjust the design accordingly. Additionally, the kerf can also impact the cost of the fabrication process, as more material may be wasted with a wider kerf.
The sheet metal design deals with multiple features that allow these parts to fulfill the requirements of the industry. Here are the 6 main common features that sheet metal parts will often have.
ParametersDescriptionRecommendationsCorner FilletsCorner fillets are rounded edges or corners on sheet metal parts that are created to avoid sharp edges, which can be dangerous and can also cause stress concentration in the metal, leading to failure.&#; Size: The size of the fillet should be at least equal to the thickness of the sheet metal. In other words, a 2mm fillet should be used for sheet metal that is 2mm thick or less.The recommended thickness for sheet metal depends on the specific application and the material being used. Generally, thicker metals provide greater strength and durability, while thinner metals are more flexible and lightweight. Common thicknesses for sheet metal range from 0.5 mm to 6 mm, but can vary based on the material and intended use. Here is a chart showing the recommended material thickness for some common metals used in sheet metal fabrication.
MetalGaugeMillimetersInchesSteel/Stainless Steel/Aluminum220.80.031Steel/Stainless Steel/Aluminum201.00.039Steel/Stainless Steel/Aluminum181.20.047Steel/Stainless Steel/Aluminum161.60.063Steel/Stainless Steel/Aluminum142.00.079Steel/Stainless Steel/Aluminum122.50.098Steel/Stainless Steel/Aluminum103.20.126Note: This chart provides general guidelines and the appropriate material thickness for a given application may depend on additional factors.
Sheet metal fabrication is a complex process that involves designing, cutting, bending, and assembling sheet metal into a final product. However, even the most skilled designers can make mistakes that can lead to costly rework or scrapped parts. To avoid these costly errors, it&#;s important to be aware of the most common design mistakes and take steps to avoid them.
One common mistake to avoid is providing a CAD file with no bends. A sheet metal part without bends cannot be fabricated as a single piece and may require additional parts and labor to join multiple pieces together. It is important to include bends in the design and specify the bend angles and radii to ensure the part can be manufactured correctly.
Another similar mistake includes accidentally placing features such as holes, tabs, etc. too close to a bend. What happens if you keep the features too close? You&#;ll end up with a deformed metal part that just wastes your money and time. To avoid making this mistake, you can just implement the 4T rule in all your CAD designs. The 4T rule dictates that all features should be 4x material thickness away from any bend line at least.
It&#;s always tempting to use perpendicular lines in your CAD design. However, the reality is a bit different. Bending sheet metal mostly results in a rounded tip that gives your bend a radius. Attempting to achieve a perfectly sharp corner can result in material deformation and cracking, which can compromise the integrity of the final product. To avoid this issue, it is recommended to specify a minimum bend radius appropriate for the material and thickness being used. This will allow for a smooth transition in the bend and prevent stress concentrations that could lead to failure.
For your ease, you can easily find the bend radius of your metal parts by measuring the bent area&#;s length and dividing the answer by two. While you can easily use different radii for each bent part, it&#;s far more cost effective to use the same radius for all bends.
It&#;s always best to include as many details in your CAD file as possible, including specific hardware specifications, sizes, and locations. This will ensure a smoother fabrication process and a more accurate final product.
Imagine needing a specific clinching nut such as the CLS-440-2 for assembling a model but this detail wasn&#;t included in the CAD file. There&#;s nothing else to do besides waiting for other individuals to arrange the required hardware. Obviously, this delay will increase the assembly time and cost.
Finishing is usually the last and essential step of the manufacturing process. Most people mistake finishing for only having one function, which is to make your part look better.
In reality, the type of finishing you select can also play an important part in protecting metal components against rust or corrosion. While finishing that only focuses on the aesthetics of the metal part exists, other types of finishing are designed to increase the life span of your product through their protective characteristics.
Aesthetic finishing, such as powder coating, does offer some protection. However, several finishings such as Silk Screening are only useful to add text or images to the metal parts. Chemical Conversion Finishes have the opposite function.
These finishes alter the outermost layer of your product and work as a protective coating. Besides this, you also have the Chromate Conversion finishing that gives metal parts electrical connectivity. It also provides a primer layer for painting.
It&#;s important to understand what finishing you should use and what you should avoid. The right finish depends entirely on the application of the metal part that you&#;re designing.
You have to consider the application of the part you&#;re designing from start to finish. For example, you can&#;t use unfinished steel in a marine and salty environment. Doing so will leave your metal parts vulnerable to rust and corrosion.
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Instead, select the right sheet metal by focusing on the flowing factors. Questions like the following are extremely important.
Answering these questions will allow you to understand what your technical requirements are and let you make an informed design.
U channels are an important part of any product design and their strength mostly depends on the overall strength of the material. Neglecting to take the material strength into account can result in U channels that are too weak, leading to bending or breaking under stress. To avoid this mistake, it&#;s essential to select the appropriate material and thickness for the U channel. Based on the expected load and to factor in any additional stresses, such as vibrations or impacts, that the channel may experience in use.
No matter how simple a design is, there are high chances that it would require some welding or other mechanical joints. Some designers make the common mistake of overestimating the welding capabilities of the unit, which in turn increases the complexity and costs.
The best way forward to avoid such issues is to implement strict design for manufacturing (DFM) practices. This ensures that all features are according to the prevalent standards.
The term sheet metal is used quite widely in the industry. However, the metal used is generally one of the following.
While sheet metal generally works well without any processing, some applications take exception to this rule. The following processes are some of the most common post-processing steps for sheet metal products.
The sheet metal fabrication design guide is made to introduce all the basic concepts of the process to anyone. Manufacturing partners need to fulfill the varying requirements of the industry and comply with the ever-changing industrial standards.
RapidDirect is an experienced manufacturing partner that can help take your design from concept to production. Whether you are a startup looking to bring a new product to market or an established company seeking to streamline your manufacturing processes, our team can provide the expertise and support you need.
At RapidDirect, we understand the importance of manufacturability and how it can impact the success of your product. Our team of experts is equipped with the latest tools and technologies to provide a comprehensive design for manufacturing (DFM) analysis. We will work closely with you to optimize your design for manufacturability, identifying potential issues early on to minimize the risk of production delays or quality issues.
In addition to our sheet metal fabrication capabilities, we also specialize in CNC machining, injection molding, and 3D printing. Our manufacturing facilities are equipped with the latest equipment and technology. We can meet the needs of a variety of industries, including aerospace, automotive, medical, and consumer products.
When you partner with RapidDirect, you can trust that your products will be delivered on time, on budget, and with the highest quality standards. Contact us today to learn more about how we can help bring your design to life and accelerate your time to market.
DFMPro provides pre-configured design guidelines DFM rules for design which helps to develop better quality parts at reduced cost. Some of the common sheet metal design guidelines included are minimum distance between holes, cutouts, slots, distance between holes, cutouts, slots to part edge and bends, multiple bends in same direction, minimum bend radius, minimum radius of rolled hem, open hem and tear drop hem, minimum flange width, minimum size of slots, holes and many other design guidelines.
DFMPro sheet metal design guidelines are highly customizable and provides the flexibility to configure the available sheet metal design rules as per organization specific design rules.It also provides the ability to add new design for manufacturing rules easily into its existing database
The section below contains examples of some design guidelines for sheet metal. These guidelines may help companies to avoid rejections and rework due to engineering errors leading to higher cost of quality and delay in the delivery to customer.
Minimum Distance from Extruded Hole to Part EdgeExtruding metal is one of the most extreme pressure applications in press working and generates lot of friction and heat. If an extruded hole is too close to the part edge, it can lead to deformation or tearing of the metal. It is recommended that the minimum distance between the extruded holes to part edge should be at least three times the thickness of sheet.
Minimum Distance Between Extruded HolesCertain distance should be maintained between two extruded holes in sheet metal designs. If extruded holes are too close it can lead to metal deformation. It is recommended that the minimum distance between two extruded holes should be six times the thickness of sheet metal.
Minimum Hole DiameterThe diameter of the hole in sheet metal part should not be very small, small holes are created by piercing operation and for manufacture small holes, small sizes punches are required. Small hole size in sheet metal requires smaller size punching tool which may leads to break during the operation. It is recommended that the diameter of the hole should be equal or more than the thickness of the sheet metal.
Maximum Embossment DepthEmbosses are small, shallow formed projections on the surface of stamped parts. During this operation, stretching is the main deformation mode resulting in high tension. Thereby the metal is subject to excessive thinning or fracturing. Consequently, the depth of the embossed feature is restricted by the material&#;s thickness and ability to stretch in addition to the emboss geometry.It is recommended that the maximum depth of embossment be less than or equal to three times material thickness.
Minimum Bend RadiusMinimum bend radii requirements can vary depending on applications and material. For aerospace and space applications, the values may be higher. When the radius is less than recommended, this can cause material flow problems in soft material and fracturing in hard material. Localized necking or fracture may also occur in such cases. It is recommended that minimum inner bend radius should be at least 1 times material thickness.
Curl Feature GuidelinesCurling sheet metal is the process of adding a hollow, circular roll to the edge of the sheet. The curled edge provides strength to the edge and makes it safe for handling. Curls are most often used to remove a sharp untreated edge and make it safe for handling.It is recommended that:
Hemming is nothing but to fold the metal back on itself. In Sheet Metal hems are used to create folds in sheet metal in order to stiffen edges and create an edge safe to touch. Hems are most often used to remove a sharp untreated edge and make it safe for handling. Hems are commonly used to hide imperfections and provide a generally safer edge to handle. a combination of two hems can create strong, tight joints with little or minimal fastening. Hems can even be used to strategically double the thickness of metal in areas of a part which may require extra support. It is recommended that:
Notching is a shearing operation that removes a section from the outer edge of the metal strip or part. In case, distance between the notches to bend is very small then distortion of sheet metal may take place.To avoid such condition notch should be placed at appropriate distance from bend with respect to sheet thickness. Notching is a low-cost process, particularly for its low tooling costs with a small range of standard punches. DFMPro sheet metal design recommendations for Notch Feature:
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