Convert SLDASM to STP

A recipient may need an assembly in STEP format to open it in CATIA, Creo, Fusion, FreeCAD, a CAM system, or an inspection application without SolidWorks. Exporting also packages the assembly’s usable geometry for supplier exchange, manufacturing review, or archiving.

What the SLDASM format is

.sldasm is the native SolidWorks assembly format from Dassault Systèmes. It stores the assembly hierarchy, component positions, mates, configurations, display states, and links to individual .sldprt part files and subassemblies.

An SLDASM file is normally not self-contained. SolidWorks records the locations of referenced parts, so opening only the top-level assembly can produce missing-component warnings. Use SolidWorks or a translator that supports the relevant SolidWorks release; ordinary viewers and many online converters cannot convert an assembly from the .sldasm file alone.

What the STP format is

.stp and .step are filename extensions for STEP, the ISO 10303 neutral CAD exchange format. STEP transfers precise boundary-representation solids and surfaces between SolidWorks, CATIA, Creo, Siemens NX, Fusion, FreeCAD, CAM software, and inspection systems.

STEP generally transfers solid geometry, surface geometry, assembly relationships, names, and sometimes colors more effectively than polygon formats such as STL. It does not preserve SolidWorks feature history, sketches, equations, mates, configurations, or parametric design intent. STEP AP203, AP214, and AP242 support different amounts of product structure and metadata; the available export options depend on the SolidWorks version and the receiving application.

How to convert the assembly

Using SolidWorks

1. Open the assembly in SolidWorks and choose File → Pack and Go to collect the top-level assembly, subassemblies, parts, and related references in a working folder. Keep the original project unchanged.
2. Open the collected assembly and resolve missing, lightweight, suppressed, or unavailable components. Rebuild with Ctrl+B, or use Ctrl+Q for a forced rebuild.
3. Select the required configuration and display state. Suppressed, hidden, or excluded components may be absent from the exported result, depending on the configuration and export settings.
4. Choose File → Save As, select STEP AP214, STEP AP242, or another STEP option provided by that SolidWorks release, and enter the output filename.
5. In the STEP options, preserve assembly structure if the recipient needs separate components. Set the export units explicitly when available; do not assume the receiving application will choose the intended millimeter or inch setting.
6. Open the resulting .stp file in SolidWorks or the target application. Check component count, hierarchy, orientation, units, visible geometry, and at least one known dimension.

SolidWorks is usually the safest converter because it resolves its own assembly references and exports directly from the native model. Exact STEP standards and option names vary by release.

Using a third-party converter

CAD Exchanger Desktop and CAD Exchanger Cloud are established alternatives when SolidWorks is unavailable. Confirm that the product version supports the specific SolidWorks .sldasm and .sldprt versions before conversion. Upload or open the complete collected assembly package, select STEP as the output format, and inspect the result in a CAD viewer.

Online conversion sends design data to an external service. Do not upload confidential models unless the provider’s retention, deletion, access-control, and encryption terms meet the project requirements. Large assemblies, missing references, unsupported newer SolidWorks versions, proprietary features, and corrupted files can cause failed or incomplete translations.

Quality and compatibility limits

• References: Missing parts or subassemblies produce incomplete geometry. File → Pack and Go is safer than manually copying files because it gathers the recorded dependencies.
• Configurations: Export the required configuration explicitly. One STEP export normally represents one selected assembly state, not every SolidWorks configuration.
• Assembly structure: A STEP file can retain product structure, but the receiving application may flatten it into separate bodies or files. Confirm the import behavior before delivery.
• Design history: The recipient receives translated geometry rather than an editable SolidWorks feature tree. Parametric changes require the original SLDASM and referenced SLDPRT files.
• Geometry: Translation can introduce tolerance gaps, missing faces, or altered small features. Inspect mating interfaces, bores, thin walls, threaded details, and free surfaces before machining or tooling.
• Units: STEP stores unit information, but importers can apply document or template settings incorrectly. Verify a known dimension after import.
• File size: A single STEP file may be easier to distribute than the complete native reference set, but detailed assemblies can still produce large files.