Manufacturing | Suspended Ceilings - Algorithmic Sheet Metal Folding
We engineered a computational geometry solver that automates the complex unfolding of bespoke ceiling panels. By implementing neutral axis algorithms to solve for material deformation and K-factors, the tool utilizes a headless Rhino backend to transform raw 3D design geometry into fabrication-ready flat patterns in milliseconds.
- Client
- Private Client
- Timeline
- 2025
- Service
- Computational Design→
The Engineering Challenge
The client, a global leader in suspended ceilings, relied on a manual 2D AutoCAD for panel design and specialist 3D fabrication tools to calculate the flat cutting pattern of each fold of a ceiling panel. The workflow was time-intensive and required specialist technicians to ensure that the flat patterns, once folded by the fabrication team, precisely matched the ceiling panels being designed.
The goal was to automate this process and enable them to create the flat cutting patterns for any panel by only specifying the material, its thickness, and its K-Factor. All whilst allowing the design team to keep using the AutoCAD application they are comfortable in and experts at using. However, standard AutoCAD APIs lacked the geometric computational power to handle complex surface intersections and real-time 3D visualization. The solution required a paradigm shift: an application that could "think" in 3D logic but deliver standard 2D AutoCAD drawings.
The Solution Architecture
We engineered the Sheet Metal Folding API, a domain-driven computational engine built on Rhino.Inside. It bypasses the limitations of standard CAD tools by performing unfolding calculations in a platform-agnostic geometry layer before generating output.
Neutral Axis Algorithms
The core innovation is the mathematical modeling of the bend itself.
- Bend Allowance: We implemented algorithms to calculate the exact arc length consumed by each fold based on the material's specific K-Factor (ratio of neutral axis position).
- Solving Plane Strategies: Using the Strategy Pattern, the solver dynamically applies different coordinate systems for Convex, Concave, and "Flipped" bends (reflex angles >180°), ensuring accurate geometry regardless of panel topology.
Five-Phase Pipeline
The engine operates as a linear transformation pipeline:
- Topology Analysis: Validates manifold geometry and builds an adjacency graph of all faces.
- Tree Construction: Organizes faces into a hierarchy rooted at the largest surface.
- Fold Calculation: Computes the neutral axis arc and Outside Setback (OSSB) for every edge.
- Flat Pattern Assembly: Recursively traverses the face tree, applying transforms to lay out the 2D pattern.
- Output Generation: Produces 2D cutting curves (DXF-ready) and a 3D validation model via Boolean union.
Three-Tier Geometry Abstraction
To ensure robustness, we architected a strictly layered geometry system.
- Internal Types: All physics and math calculations occur in our custom lightweight geometry library, ensuring zero dependency on the CAD platform during calculation.
- Rhino Kernel: We only call RhinoCommon for complex Boolean operations (like merging thickened solids), keeping the core logic fast and testable.
- CAD Output: The final result is converted to native AutoCAD entities only at the very last step.
The Result
The tool transformed a manual engineering bottleneck into a background task.
- Speed: Unfolding time dropped to <1 second per panel.
- Scale: The system can process an entire project's library in minutes.
- Accuracy: By codifying the K-Factor logic, the tool eliminates human calculation errors, reducing material waste on the factory floor.
- < 1s
- Folding Time Per Panel
- Unlimited
- Material/ Thickness Support
- 5-Phase
- Transformation Pipeline
- 100%
- Neutral Axis Accuracy