Convert SLDASM to 3MF in your application
3D InterOp is a CAD interoperability SDK that lets your software read SLDASM files and write 3MF, generating the 3MF mesh from the geometry it reads, with tessellation settings your application controls.
Spatial does not offer an online converter or a desktop conversion app. 3D InterOp is a component that software vendors embed in their own products.
- Reads SOLIDWORKS assembly · Writes 3MF
- Exact geometry → triangle mesh
- C++ / C# APIs
SLDASM to 3MF at a glance
SOLIDWORKS assembly stores exact geometry; 3MF stores triangles. The translation is a tessellation, and the settings you choose decide how close the mesh stays to the original.
| SOLIDWORKS assembly (source) | 3MF (target) | |
|---|---|---|
| Full name | SOLIDWORKS Assembly | 3D Manufacturing Format |
| Standard / owner | Dassault Systèmes SOLIDWORKS | 3MF Consortium, ISO/IEC 25422 |
| File extensions | .sldasm | .3mf |
| Geometry | Exact B-Rep (in the referenced parts) | Triangle mesh |
| Assemblies / structure | Yes | Objects and build items |
| PMI | Semantic (DimXpert) and graphical, SOLIDWORKS 2014 and later | None |
| 3D InterOp support | Read only | Read and write |
What's preserved, what changes
Here is what your application can expect to carry across from SOLIDWORKS assembly to 3MF.
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Changes
Geometry is tessellatedThe exact SOLIDWORKS assembly B-Rep is replaced by a triangle mesh, generated by 3D InterOp from the exact geometry it reads. Accuracy depends on the tessellation settings your application uses.
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Changes
Assembly structure3MF has no native assembly hierarchy. Decide in your application how SOLIDWORKS assembly product structure is grouped or flattened before writing.
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Not carried
PMI3MF has no place for PMI, so the PMI read from SLDASM isn’t written.
Why software vendors add SLDASM to 3MF conversion
Additive manufacturing
3MF is still the input most slicers and print services expect. Writing it lets your users send parts to print directly.
Mesh-based processing
Inspection, scan comparison and mesh-editing tools work on triangles. A mesh output gives them a model they can open anywhere.
Lightweight sharing
A mesh is simpler than the native CAD file and needs no CAD system to open.
Things to check before you ship
- Written 3MF versions: 3MF 1.1.
- The 3MF writer is available through the UConnect interface only.
- Supported SLDASM input: SOLIDWORKS 98 to 2026.
- Test tessellation settings on your heaviest parts: finer meshes mean larger files.
- Validate a sample of translated files in the target system your users actually work with.
Working with Spatial was a real milestone for us: Thanks to the powerful 3DInterOp library, we were able to successfully bring our complex CAD-based solutions to the cloud while remaining flexible to meet individual customer requirements. For us, Spatial is not just a technology partner, but a true enabler of our product strategy.
Dr. Arno Michelis, Founder, Simus Systems
Read the Case StudyAbout the formats
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Source format
What is an SLDASM (.sldasm) file?
An SLDASM file is a SOLIDWORKS assembly. It defines how parts and sub-assemblies fit together and references the SLDPRT files that hold their geometry.
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Target format
What is a 3MF (.3mf) file?
3MF is an open format for additive manufacturing, defined by the 3MF Consortium. It stores triangle meshes with units, colors and build information in a single package.
Frequently asked questions
3D InterOp tessellates the geometry it reads from SLDASM when it writes 3MF. Your application sets the tolerances, so it controls the trade-off between accuracy and file size.
3MF has no place for PMI, so the PMI read from SLDASM isn’t written. Your application can still access it after import, or offer STEP AP242 as an output.
3MF has no assembly hierarchy, so your application decides how the SLDASM structure is grouped or flattened before writing.
The 3MF writer is available through the 3D InterOp UConnect interface.
Yes. If your application uses Parasolid, a Parasolid-based SOLIDWORKS reader is available.
Semantic PMI from SOLIDWORKS 2014 to 2026, and graphical PMI from SOLIDWORKS 2014 onwards.
3D InterOp reads SOLIDWORKS 98 to 2026.
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Building software that needs to convert SLDASM to 3MF?
3D InterOp is an SDK that lets your application read SOLIDWORKS assembly and write 3MF alongside 30+ CAD and BIM formats.