The manufacturing industry operates on precision, speed, and adaptability. When it comes to fabricating components from sheet metal, the journey from a 3D concept to a 2D cut file must be seamless. Any miscalculation in bend allowances or material thickness can result in wasted material, delayed production, and costly rework. Mastering sheet metal design in BricsCAD can help engineers and fabricators create folded models, calculate unfolded geometry and prepare manufacturing data. The accuracy and production readiness of the result still depend on valid geometry, correctly configured bend data and verification against the intended material, tooling and CAM process.
Unlike traditional history-based CAD systems, BricsCAD offers a uniquely flexible environment. Whether you are conceptualising a bespoke enclosure, detailing a complex HVAC transition, or importing legacy data from another software, understanding how to use BricsCAD’s direct modelling, sheet metal recognition and unfolding tools can reduce the amount of manual remodelling required, particularly when working with imported solid geometry.
Let us examine the workflow from initial 3D modelling through to generating and validating 2D profiles for fabrication.
To appreciate the BricsCAD Mechanical sheet metal toolset features, it is essential to understand how it differs from traditional parametric modelling.
BricsCAD Mechanical supports history independent direct modelling, while SOLIDWORKS commonly represents modelling operations through its FeatureManager design tree and parent and child relationships. SOLIDWORKS also provides FeatureWorks tools for recognising features in imported bodies. The two products therefore offer different editing workflows, rather than one product being inherently unable to edit imported or dependent geometry.
BricsCAD Mechanical supports history independent direct modelling, allowing suitable geometry to be modified without following a chronological feature sequence. Its SMCONVERT command analyses suitable native or imported solids and recognises sheet metal features such as flanges and bends. Any unresolved bends, junctions or invalid geometry can then be repaired with the appropriate sheet metal commands. This freedom makes BricsCAD an exceptionally powerful tool for bespoke fabricators and contract manufacturers who frequently work with third-party CAD files.
There are generally two ways to begin a sheet metal project: designing a native part from scratch using sheet metal specific commands, or converting an existing solid.
When designing natively, you can use SMFLANGE to create the initial base flange from a closed planar profile. Use SMFLANGEEDGE to pull selected edges into additional edge flanges. The direct modelling approach allows you to drag a flange to the exact millimetre required. As sheet metal features are created, they normally inherit thickness, bend radius, relief and other default values from the drawing’s Sheet metal context. Individual features can override the global values, and automatic relief creation depends on the command and geometry being used.
One of the software’s most celebrated capabilities is how to convert 3D solids to sheet metal in BricsCAD. If you have modelled a blocky concept or received a STEP file of an enclosure, you can use SMCONVERT to recognise sheet metal features in the solid and then repair or complete the model as required.
Corner and bend reliefs may be created automatically during certain native flange operations. For converted models, SMRELIEF can analyse selected geometry or the complete model and create required reliefs using the configured sheet metal settings. The resulting relief geometry should still be checked against the intended material and forming process.
Sheet metal is rarely just simple right angles. Modern fabrication requires sophisticated shaping, and BricsCAD provides the tools necessary to achieve this.
When creating enclosures that require clean, welded corners, you will often rely on mitred edges. The best practices for mitered flange design involve ensuring adequate gaps for welding and accounting for material spring-back. BricsCAD represents this condition with a mitre feature, which can be created through SMFLANGEEDGE or SMSPLIT. The Miter gap can be controlled globally or for an individual feature in the Mechanical Browser. The required gap should be determined from the applicable fabrication and welding specification.
For industries dealing with ducting, hoppers, or exhaust systems, creating lofted bends for complex transitions is a daily requirement. A classic example is a square-to-round transition. BricsCAD handles this through the SMLOFT command. SMLOFT creates sheet metal geometry between two profile entities. Straight profile segments can become flanges, while curved segments can become lofted bends. Cylindrical and conical lofted bends can use analytical unfolding, while other lofted bends use an approximate unfolding controlled by a specified number of subdivisions. The appropriate forming method must be assessed against the available manufacturing equipment.
A beautiful 3D model is useless if it cannot be formed on a press brake. Therefore, optimizing bend radius for fabrication is a critical step. There is no universal minimum inside bend radius for every type of steel or sheet metal process. The required radius depends on material grade, thickness, bend direction, tooling, die opening and bending method. Using a radius below the material or supplier recommendation increases the risk of cracking and other forming problems. BricsCAD allows the global bend radius in the Sheet metal context to be changed. Bends that are configured to use the global value will update, while bends with individual feature overrides can retain their local values. The selected radius must still be checked against the intended tools and die opening.
The secret to generating an accurate BricsCAD flat pattern lies in managing sheet metal material properties and thickness. When a piece of metal is bent, the inner surface compresses, and the outer surface stretches. The neutral axis, the theoretical plane within the material that neither compresses nor stretches, dictates the flat length of the part.
This is where calculating K-factor and bend allowance becomes paramount.
If your K-factor is incorrect, your flat pattern will be too long or too short. By the time the operator finishes a part with four bends, the cumulative error could throw the final dimensions off by several millimetres, resulting in a scrapped part.
BricsCAD handles this beautifully. BricsCAD allows a K factor to be assigned to a sheet metal part or a CSV bend table to be attached through the Mechanical Browser. A bend table can contain bend deduction values and optional die width data for the relevant thickness. BricsCAD uses this information to calculate the unfolded length, but the result should be validated against the actual material, tooling and bending process.
Components are rarely designed in isolation. They must fit together with brackets, fasteners, and other structural elements. BricsCAD Mechanical allows you to design sheet metal parts within the context of a larger machine.
By utilising associative constraints for sheet metal assemblies, you can lock the face of a sheet metal bracket to the mounting holes of a motor. Assembly constraints can maintain defined geometric relationships between the motor and bracket. The bracket will resize automatically only when the required dimensional constraints, parameters and expressions have been created to control that behaviour. This top-down design methodology drastically reduces errors during the final assembly phase.
Once the 3D modelling is complete, the final hurdle is transitioning to the 2D manufacturing space. SMUNFOLD creates an unfolded solid body after the user selects a starting flange face and placement point. The result can be retained as a block in the current drawing, saved as a separate 3D drawing, or converted and saved as 2D DWG or DXF geometry.
A valid sheet metal model can be unfolded with SMUNFOLD, but the user must select the starting face, place the result and choose the required output options. Production release also requires checks for bend calculation data, overlaps, orientation, units, layers and compatibility with the receiving CAM process. When you execute the unfold command, BricsCAD calculates the material stretching, applies the bend allowances, and lays the part flat. The Keep option retains the unfolded part as a block in the current drawing. When 2D output is created, BricsCAD places contours, bend lines, dimensions, form representations, bend annotations and attributes on dedicated layers according to the unfolding settings.
Inevitably, designers run into hurdles. If you find yourself asking, “why is my 3D model not unfolding?”, it usually boils down to a few common geometry issues. BricsCAD includes an intelligent colour-coding system to help you diagnose these problems.
Addressing reported model and unfolding issues improves the reliability of the flat pattern. Final manufacturability still depends on validated bend data, material behaviour, tooling limits, collision checks and verification in the receiving manufacturing process.
The final stage of Sheet Metal Design in BricsCAD from Model to Flat Pattern is getting the data to the machines. Modern fabrication relies heavily on CNC laser cutting, plasma cutting, and waterjets.
Exporting sheet metal DXF for CNC laser cutting is highly automated within BricsCAD. Once the BricsCAD flat pattern is generated, you can export it directly using the SMEXPORT2D command.
To ensure the CNC programmer has exactly what they need, BricsCAD allows for extensive customisation of the DXF output:
Standardising the DXF output can reduce manual clean up and lower the risk of interpretation errors. The exported file should still be checked in the receiving CAM system before production.
Mastering BricsCAD sheet metal is about much more than just learning a few software commands; it is about embracing a smarter, more agile way of manufacturing. The transition from traditional, rigid CAD structures to a dynamic, direct-modelling environment allows engineers to iterate faster and handle late-stage design changes without frustration.
From the initial conceptualisation of complex lofted transitions to the precise calculation of bend allowances, BricsCAD provides an unbroken, highly intelligent chain of tools. Correct conversion, bend data, overlap checking and controlled export can improve consistency between the digital model and the fabricated part. Final fit must still be confirmed through appropriate design checks, tolerances and manufacturing validation.
Bridging the gap between the digital screen and the physical machine is the ultimate goal of any CAD software. With its powerful, intuitive, and manufacturing-focused toolset, BricsCAD proves itself to be an indispensable asset for the modern sheet metal fabricator.
Question: How is BricsCAD’s sheet metal approach different from history-based systems like SolidWorks, and why does it matter? Short answer: BricsCAD Mechanical supports history independent direct modelling and can recognise sheet metal features in suitable imported solids with SMCONVERT. SOLIDWORKS commonly uses a FeatureManager design tree with parent and child relationships and also provides imported feature recognition tools. The practical difference is the editing workflow, rather than a guarantee that one system never encounters dependency or reference problems.
Question: What’s the fastest, reliable way to convert an existing 3D solid into a manufacturable sheet metal part in BricsCAD? Short answer: Follow a shell–convert–refine workflow:
Question: How do I ensure my flat pattern is dimensionally accurate after unfolding? Short answer: Control your material intelligence, thickness, K‑factor, and bend allowances.
