Communication of accurate design intent through detailed yet clutter-free fabrication shop drawings is critical to metal fabricators. Leveraging industry best practices for modeling and drafting will minimize rework and optimize costs.
Sheet metal components are frequently used in industrial equipment, furniture, kiosks, doors and windows, HVAC equipment, roofing and electrical enclosures. And each component, assembly and sub-assembly has a customized manufacturing approach.
Any typical sheet metal fabricator spends a huge amount of time, energy and money to fabricate these unique products. It requires detailed understanding of design features, parameters like sheet thickness, bends, holes, slots, notches and their specific standards. Designers and fabricators should have a thorough understanding of manufacturing process dynamics and types of material for effective sheet metal part modeling.
Today, fabricators of MSME and SME segment of sheet metal industry creating furniture, building components, and process equipment face challenges like:
CAD technology has significantly reduced design-to-manufacturing time and enhanced sheet metal part modeling accuracy for manufacturers. Best practices in sheet metal drawings and detailing drive:
Feature based parametric 3D models and 2D drawings share parent-child relationship as drawings are generated from models. This bi-directional parametric link between models and drawings allows the design engineer to evaluate changes in 2D sheet metal shop drawings and 3D model simultaneously.
Complex sheet metal components use multiple features to convey design intent and show part functionality. Figure 1 shows a typical sheet metal component model with design features.
Figure 1: Sheet metal features and their categories
If you are working on a single component, you can apply Design for Manufacturing (DFM) concepts and it directly conforms to standard manufacturing processes. Adherence to DFM guidelines for 3D models helps optimize manufacturing operations such as nesting, bending, holes, and punching.
Benefits of using of FBPM:
Parametric modeling of sheet metal industrial equipment for plant reengineering
Hitech CADD Services’ design engineers carried out reverse engineering of a recycling plant in Europe. They recorded physical dimensions and developed a 3D plant assembly model in SolidWorks. Deliverables also included GA drawings, 2D part drawings and parametric 3D models. That assisted design engineers to take informed decisions for plant restructuring and improving efficiency.
Read Complete Case Study »Top-down approach is used for modeling a product with multi-component sheet metal parts. This design approach allows you to create a geometric frame having space constraints assigned to all parts and sub-assemblies. It builds the master model in such a way that they can be used for CTO and ETO feature customization for products such as doors and windows, metal and wooden furniture etc.
CAD tools like SolidWorks, Inventor and Creo allow a top-down approach for very large and complex assemblies. These include heavy duty bulk material handling plants having 10,000+ components in a single master model. These CAD platforms are also fit to handle small assemblies of sheet metal door frame having not more than 20 to 30 parts with dexterity.
Figure 2: Top-Down design approach for a small sheet metal assembly
Advantages of top-down design approach:
Faster installation of walkway and hopper with top-down design approach
Hitech CADD Services engineers developed manufacturing drawings along with 3D models of a recycling industry plant and equipment manufacturer. Project engineers adopted a top-down approach to convert STEP files and solid models of the plant assembly for walkways and hoppers. A systematic approach of building the model met all design guidelines, avoided reworks and saved time in redesigning.
Read Complete Case Study »Design for Manufacturing (DFM) and Design for manufacturing and assembly (DFMA) allow design engineers to capture requirements as per shop floor capabilities. Following these guidelines nullifies most of the design errors that rise from non-conformity with the standard shop floor practices.
DFM guidelines help design engineer bridge the gap between real world and ideal world while creating features like holes, slots, bends, end reliefs, etc. Below, figure 3 and 4, are examples of hole creation and bend radius creation respectively, in sheet metal.
Figure 3: Punching holes in sheet metal plates as per DFM rules
Figure 4: Bending failure in sheet metal plate without considering grain direction
With DFMA guidelines, engineers are empowered to optimize designs by controlling the number of components and steps involved in manufacturing. With fewer components, fabricators can save costs and speed up the production process due to ease in assembly and fabrication.
Figure 5: Considering number of sheet metal parts in the assembly as per DFM guidelines
Advantages of DFM and DFMA:
Eliminated manufacturing rework using DFM rules for a stairlift manufacturer
Hitech CADD Services’s sheet metal design team migrated legacy design data from AutoCAD to SolidWorks using APIs for a Stairlift manufacturer. This enabled standardizing all files in SolidWorks as per DFM guidelines and international design standards to eliminate rework.
Read Complete Case Study »Advancement in tools like SolidWorks ensures incorporation of high level of manufacturing and quality information in models. They have provisions to annotate models with product manufacturing information and create single source of truth for all design and manufacturing stakeholders. By saving all information in one place, this concept has a significant potential to meet the needs of Industry 4.0.
Figure 6: MBD representation of a sheet metal plate
A complete set of product information for manufacturing and suppliers such as quality measurement, tolerances, other footnotes etc. is communicated using a comprehensive 3D model. This is called the Model Based Definition (MBD) approach.
MBD creates a single, reliable CAD file for the entire value chain to improve collaboration, save time and prevent errors. If used efficiently along with DFM, DFMA, FBPM, and Top-Down approach, MBD can prove to be significantly advantageous to the manufacturers.
Advantages of MBD:
MBD reduces 50% engineering lead time for electroform systems manufacturer
An electroform systems manufacturer accelerated design development of high-precision metal parts and cut the time to almost half using SolidWorks MBD. A single file for all inter-team communication accelerated publishing of PMI in 10 minutes instead of one day and eliminated the need for paper drawings. (Source: SolidWorks)
With advanced CAD technologies and smart modeling practices in SolidWorks, Inventor and other tools, sheet metal component manufacturers and fabricators can speed up their design cycles. Best practices such as DFMA, MBD, top-down and FBPM improve design engineers’ productivity and offer a first time right design approach. They bring down design iterations during sheet metal part modeling and hence the total costs of manufacturing projects.
These best practices have been in use in the engineering design industry for a long time and have proved beneficial for fabricators. As the industry gears up for Industry 4.0, shop floor fabricators seek enhanced communication across teams. Adopting workflows like MBD or FBPM and DFM is critical to staying competitive.
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Sandip Shah is a mechanical design engineer with a track record of 22+ years of delivering winning solutions across new product design, value engineering, and digital manufacturing/IOT projects. He has successfully steered business units of 2 million through his excellence in project management, global account management and lean planning in CAD/CAM and CAE tools.
Nimesh Soni with 15+ years of managerial role in industrial design industry, manages furniture design vertical at HitechCADD Services. For the past 9 years at Hitech, he has delivered winning solutions for a range of turnkey projects with his expertise in SAP/PLM and CAD tools. His current research work towards a doctoral degree in IOT gives him an advantage in identifying automation opportunities across design-to-manufacturing cycle.
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Sep 6th, 2022 