Being lightweight, non-corrosive, conducive and strong, sheet metal finds myriad of applications in almost every industry. The design of sheet metal as such is critical and is a strong backbone for a good quality product.

Being a sheet metal designer, it is important to have a set of goals and design strategies defined when developing a sheet metal product to ensure that the product is cost-effective as well as feasible to manufacture. Right from defining the function, assembly, mechanical properties and manufacturing properties, the designer must specify each of these aspects clearly in the design cycle. While defining a set of guidelines for sheet metal design may vary based on application and manufacturing capabilities, there are few standard design and manufacturing practices, which are established with thorough analysis of results and changing industrial requirements.

1. Minimum Bend Radius

It is important that the sheet metal stock must withstand stress in a flexure test. The test is used to visualize the K-factor in the area of bending. The process of bending usually generates more strain on the outer surface of the sheet metal as compared to the inner one. This effect results in crack formation, if the sheet metal is bent beyond a particular point. This point is termed as minimum bend radius, and a sheet metal designer must keep in mind this minimum bend radius while developing design ideas. For design cases where the need is to increase the minimum bend radius, the sheet metal would also require to undergo processes like polishing or grounding.

2. Hole Sizing

3D CAD model of a sheet metal component developed in SolidWorks

In a sheet metal stock, specifying the hole size, location and its alignment is critical. It is always better to specify the hole size a bit more than the blank thickness. A hole diameter less than the stock thickness results in higher punch loading, longer burnish in the hole and excessive burr. It also leads to slug pulling during punch withdrawal, ultimately affecting the life of both punch and the stock. Spacing between the holes matter too and should be at least two times the blank thickness, if not more. The distance between holes ensure strength of the stock as well as avoid the holes from deformation during the bending or forming process.

3. Bends, Beads and Flanges

3D CAD model of an automobile component developed using SolidWorks

It is too common to receive sheet metal part models with a common modeling mistakes related to specifying bends and fillets, especially, in cases where multiple vendors are involved. A formed part is then often different from what it looks virtually. As an engineer creating a virtual sheet metal part, it is even important to understand the importance of bend relief meant to avoid metal tearing. Moreover, features like beads and flanges are there for specific purpose. They reduce the spring back effect and add stiffness to the overall design of the part or a product.

4. Room for Fabrication

According to the end use, sheet metal can often be utilized for multiple processes like welding, which requires grinding. As such, it is important for the sheet metal designer to ensure that there is enough room to accommodate the fabrication option.

5. Minimum Flange Width

Flanges help in creating the sheet metal part quickly and conveniently. To define the flange, sheet metal designer must use a standard rule which suggests that the flange width should not be less than four time the sheet metal stock thickness. Less flange width will cause the tool to leave impression on the sheet metal surface.

6. Welding

Sheet metal designer often include provision for brackets in the design without actually looking for other possible alternatives. Welding should only be adopted if it is an absolute necessity, otherwise in most cases, fasteners can help you achieve similar design goals efficiently with minimal cost and simple design.

7. Edge Bending

Edge bending is utilized in almost every sheet metal product design to give strength at the edges as well keep the design safe to be used by the end customers. However, ineffective edge bends can also give rise to unwanted complexities. To avoid any issues during the bend forming, it is essential to have provisions for angles less than 90 degrees to reduce the cost and usage of complex equipment for bending.

At TrueCADD, we strictly adhere to these guidelines along with other design specific instructions to deliver accurate product designs for efficient manufacturability and assembly. Our team of design engineers delivered design support to sheet metal fabricators as well as manufacturers of sheet metal components like furniture, sheet metal roofing, wall panels and industrial equipment. Interested in developing an accurate and cost-effective sheet metal design for your product? Visit us at www.truecadd.com or drop us an inquiry at info@truecadd.com

About Author: Gaurang Trivedi is Engineering consultant at TrueCADD. He has applied his engineering expertise across several highly complex and big scale projects, consequently managing to flawlessly deliver as per the client requirements.

1. Minimum Bend Radius