Sheet metal is one of the most common manufacturing processes in UK engineering and product design — brackets, enclosures, chassis, panels, and ducting are all sheet metal applications that engineers encounter daily. Autodesk Inventor includes a dedicated Sheet Metal environment that understands the rules of sheet metal manufacturing: bend relief, K-factor, minimum bend radius, and flat pattern unfolding. Designing in this environment rather than as a standard solid part ensures that your designs are genuinely manufacturable and that the flat patterns you send to the laser cutter or press brake are accurate.
This tutorial walks through creating a practical sheet metal bracket from scratch in Inventor 2026.
Opening the Sheet Metal Environment
In Inventor, sheet metal parts are created in a dedicated Sheet Metal (.ipt) template, not the standard part template. When creating a new file, select the Sheet Metal (mm).ipt template from the templates list.
This automatically activates the Sheet Metal tab on the ribbon and loads the sheet metal rules and features specific to this environment. You will notice the ribbon now shows tools like Face, Flange, Contour Flange, Bend, Fold, and Flat Pattern — these replace the standard 3D Model features.
Setting Up Sheet Metal Rules
Before modelling, configure your sheet metal rules to match the material and process you are designing for. Sheet metal rules control:
- Material thickness — the gauge of sheet used (e.g., 2mm mild steel, 1.5mm stainless, 1mm aluminium)
- K-factor — a value between 0 and 1 that defines where the neutral axis sits within the material during bending, affecting the flat pattern calculation. Common values are 0.33 for most metals; some materials and die sets use different values.
- Bend radius — the internal radius applied to all bends
- Bend relief shape and size — the relief cuts added at the end of flanges to prevent tearing
To access sheet metal rules: click the Sheet Metal Defaults button (the small icon at the bottom-right of the Sheet Metal panel on the ribbon). Here you can create named rules for different materials and thickness combinations, then switch between them as needed.
Creating the Base Face
Sheet metal parts in Inventor begin with a Face — a flat face that represents the base of the part. Unlike standard solid modelling where you extrude a sketch to a depth equal to the part height, in Sheet Metal the Face command extrudes to the sheet thickness automatically.
- On the Sheet Metal tab, click Face
- Click Create Sketch to draw the profile of the base face
- Sketch the outline of your bracket’s base (e.g., a 100mm × 80mm rectangle for our example bracket)
- Finish the sketch — Inventor creates a flat face at the specified sheet thickness
The face represents the flat portion of the sheet from which flanges and bends will be added.
Adding Flanges
A flange is a bend added to an edge of the sheet metal part, producing an upstanding lip. To add a flange to our bracket:
- On the Sheet Metal tab, click Flange
- Select the edge you want to bend (e.g., the 100mm top edge of the base)
- In the Flange dialogue, set the height (e.g., 25mm), the bend angle (90° for a right angle), and the direction (up or down from the face)
- Set the relief type (bent, straight, or none) for the corners where the flange meets adjacent faces
- Click OK
Inventor applies the flange with the correct bend radius from your sheet metal rules and automatically calculates how the flat pattern will change. If you add flanges to both the top and bottom edges, you will have a simple U-section bracket.
Hem and Contour Flange
For more complex profiles, Inventor provides additional sheet metal features:
- Contour Flange — creates a flange along an edge using a sketch profile rather than a simple straight height. Use this for swept flanges, multi-bend profiles, and irregular shapes.
- Hem — folds the edge of the sheet back on itself, creating a safe, reinforced edge. Useful for panel edges and enclosures where a raw cut edge would be a handling hazard.
- Fold — bends the sheet along a sketched line, allowing precise control over bend location without using the standard flange workflow.
Adding Holes and Cut-Outs
Sheet metal parts typically require holes for fixing, ventilation, or component mounting. In the Sheet Metal environment, use the standard Hole feature from the 3D Model tab — Inventor handles this correctly in the sheet metal context.
For cut-outs and complex openings, switch to the sheet metal Cut feature, which creates a punched opening through the face. You can sketch any profile for the cut — rectangles, slots, circles, or custom shapes. Inventor correctly handles the cut-out in the flat pattern output.
Generating the Flat Pattern
The flat pattern is the unfolded shape that goes to your laser cutter, waterjet, or press brake programmer. In Inventor, generating the flat pattern is a single click:
- On the Sheet Metal tab, click Flat Pattern
- Inventor calculates the flat pattern using the K-factor from your sheet metal rules, accounting for material stretch during bending
- The flat pattern appears as an additional representation in the Model Browser
You can view the flat pattern at any time to check the overall blank size and verify that bend relief cuts are placed correctly. The flat pattern updates automatically if you edit the part.
Producing Manufacturing Drawings
From your sheet metal part, you can generate a Drawing file (.idw) that includes both the 3D formed view and the flat pattern. Place a flat pattern view using the Drawing Views tools, and add bend line annotations to communicate fold lines to the fabricator. Inventor automatically annotates flat patterns with bend direction indicators (mountain fold up, valley fold down) and bend angles.
Include a bend table in the drawing to list all bend operations, their radii, and directions — this is standard practice for sheet metal fabrication instructions in the UK.
Start Designing Sheet Metal Parts Today
Inventor’s sheet metal environment is one of its strongest features, providing a purpose-built workflow that produces accurate flat patterns and well-documented fabrication drawings. If you are currently designing sheet metal in a standard CAD tool without these specialist features, you are likely spending significant time on flat pattern calculations and manual checks that Inventor handles automatically.
Autodesk Inventor Professional 2026 is available from GetRenewedTech for £39.99 — the complete sheet metal design environment, along with the full Inventor Professional toolset, at an accessible price for engineering businesses of all sizes.
