Every major SolidWorks release changes something under the hood that nobody asked for. The 2025 release is no exception, and this time it’s the flat pattern engine that got reworked.
If you’ve upgraded recently and noticed that your DXF exports look different, your corner reliefs have mysterious tear lines, or your flatten sub-features are behaving strangely — you’re not imagining things. These are real changes in how SolidWorks 2025 handles sheet metal internally, and they affect anyone who relies on consistent DXF output for fabrication.
What Changed in 2025’s Flat Pattern Engine
SolidWorks 2025 introduced modifications to the corner relief processing algorithm. On paper, this is supposed to give cleaner results for complex bends. In practice, it changes the geometry of flat patterns that have been stable across multiple SolidWorks versions.
The flat pattern engine in SolidWorks is not a simple UI feature — it’s a kernel-level operation. As we documented in our flat pattern deep dive, the unfolding runs through CATIA CGM’s sheet metal body classes (CATSHMBody, CATSHMFace, CATSHMEdge) on top of Parasolid’s B-Rep representation. Changes to the corner relief algorithm are changes to how these kernel classes decompose and unfold the topology. When Dassault updates the CGM sheet metal kernel, every SolidWorks flat pattern computation can change — even on parts you haven’t touched.
The most visible change is how auto relief tear lines appear in the flattened geometry. In previous versions, these tear lines followed a predictable path based on the relief type you selected (rectangular, tear, or obround). In 2025, the algorithm recalculates the tear path using updated internal logic, which means files that were designed in 2023 or 2024 will produce slightly different flat patterns when opened in 2025.
For most display purposes, the difference is negligible. But if you’re exporting DXF files for laser cutting, even small changes to tear line geometry can affect how your nesting software interprets the part boundary.
The Flatten Sub-Feature Suppression Problem
This one is subtle but annoying. Some users have reported that the Flatten sub-feature — the feature that actually generates the flat pattern view — occasionally enters a suppressed or rollback state after file migration to 2025.
When this happens, the flat pattern appears empty or generates with incomplete geometry. The part looks fine in the folded state, but the flatten operation produces garbage. The fix is usually to delete and recreate the flat pattern feature, but that means you lose any manual adjustments you made to the flat pattern (added sketch geometry, modified bend regions, etc.).
If you’re dealing with hundreds of parts in an assembly, manually recreating flatten features isn’t realistic. This is where having a batch export tool matters — you want something that can detect when a flat pattern is invalid and flag it before you waste time debugging on the shop floor.
Corner Relief Geometry Drift
The second major issue is corner relief geometry that shifts position after upgrade. Consider a part with three bends meeting at a corner. In 2024, the rectangular relief would be centered on the intersection point. In 2025, the same relief might be offset by a fraction of a millimeter due to the updated calculation.
Again, this is usually invisible to the naked eye. But CNC machines don’t have naked eyes. They have exact coordinates, and a 0.2mm shift in a relief cutout can cause interference with adjacent bends during forming.
The fix is straightforward but tedious: open each affected part, edit the corner relief, and accept the new geometry. SolidWorks doesn’t flag these changes automatically — the file opens without errors, the flat pattern generates without warnings, and the DXF exports without complaints. The problem only shows up on the press brake.
How to Safely Migrate Sheet Metal Files to 2025
Here’s the workflow we recommend for upgrading sheet metal assemblies:
Step 1: Export Reference DXFs Before Upgrading
Before you open any files in 2025, export flat pattern DXFs of every sheet metal part using your current version. These become your baseline. If you’re working with large assemblies, batch export tools make this manageable.
Step 2: Open and Save in 2025
Open the assembly in 2025 and let it convert. Save all files. This triggers the internal migration of features to the 2025 format.
Step 3: Export New DXFs and Compare
Export the flat patterns again from 2025 and compare them against your baseline. You’re looking for:
- Boundary changes — outer profile geometry that shifted
- Relief geometry drift — corner cutouts that moved or changed shape
- Missing or extra lines — tear lines that appeared or disappeared
- Suppressed features — flat patterns that didn’t generate at all
Step 4: Fix What Changed
For parts where the geometry drifted:
- Edit the corner relief feature and reapply your preferred relief type
- Check the K-factor and bend allowance settings — these sometimes reset during migration
- Regenerate the flat pattern and verify against the baseline DXF
The K-factor setup is worth double-checking because 2025 may default to different bend calculation parameters than what you had configured.
Bend Line Behavior Changes
One more thing worth mentioning: bend line representation in the DXF output also changed slightly. The dashed line pattern for bend-up vs bend-down lines uses a different dash length in 2025. This matters if your shop floor operators identify bend direction by the line pattern, or if your nesting software uses line type to determine operations.
If your fabrication workflow depends on specific DXF layer content and metadata, verify that the layer mapping still matches what your downstream software expects. Layer names didn’t change, but the geometry on each layer may have subtle differences.
CadShift and SolidWorks 2025
CadShift’s DXF export engine was updated to handle 2025’s flat pattern changes. The batch export process detects suppressed flatten features and reports them instead of silently skipping parts. The bend line trimming feature accounts for the new dash pattern, and the metadata embedding works with the updated COM API interfaces.
If you’re on CadShift Professional, the export report will flag any parts where the flat pattern geometry differs significantly from what was expected based on the part’s bend table configuration. This catches the corner relief drift issue before the files reach the shop floor.
Should You Upgrade?
If your current version works and your shop floor processes are dialed in, there’s no compelling reason to rush to 2025 for sheet metal work specifically. The flat pattern changes are incremental improvements to edge cases, and the migration risk is real for established workflows.
If you do upgrade, budget time for the migration validation workflow described above. The actual re-export doesn’t take long, especially with batch tools, but the comparison and fix phase depends entirely on how many parts have corner reliefs or complex bend geometries.
The one thing you should not do is upgrade and assume everything is the same. It isn’t. Test with a representative subset of your assemblies first, validate the DXF output against your fabrication requirements, and only then roll out to your full part library.