Convert SLDPRT to STEP

A machine shop, CAM package, PLM system, or customer may request a STEP file because it cannot use a native .sldprt part. STEP transfers the finished 3D geometry to other CAD and manufacturing systems without requiring SOLIDWORKS.

What the SLDPRT format is

SLDPRT is the native part-file format of Dassault Systèmes SOLIDWORKS. A .sldprt file can contain parametric features, sketches, dimensions, configurations, multibody geometry, materials, custom properties, and references specific to SOLIDWORKS.

It is a proprietary native format, so another CAD application may support only certain SOLIDWORKS versions or may translate the model imperfectly. A newer SOLIDWORKS release can normally open older part files, but an older release cannot normally open files saved by a newer release.

What the STEP format is

STEP, saved as .step or .stp, is an ISO 10303 neutral CAD exchange format. It commonly transfers solid and surface geometry, curves, assembly structure, names, colors, and limited metadata, depending on the selected protocol and the exporting and importing applications.

STEP is accepted by most mechanical CAD, CAM, CMM inspection, and PLM systems. It is generally preferable to STL for machining or further CAD work because STEP retains precise boundary-representation geometry rather than a triangulated mesh.

Common protocols are AP203, AP214, and AP242. Use the protocol specified by the recipient; AP214 is broadly compatible and commonly retains colors, while AP242 supports newer exchange capabilities. Use AP203 only when a legacy system explicitly requires it.

Convert with SOLIDWORKS

Exporting from SOLIDWORKS is the most reliable method because it reads the native model directly.

1. Open the .sldprt file in the same or a newer compatible SOLIDWORKS release.
2. Activate the required configuration in the ConfigurationManager. A STEP export normally represents the active configuration, not all configuration logic.
3. Force a full rebuild with Ctrl+Q, then resolve any rebuild errors, missing external references, or unwanted suppressed bodies.
4. Select File → Save As.
5. Set Save as type to a STEP format, then select Options to choose AP203, AP214, or AP242 if the installed SOLIDWORKS version provides those choices.
6. Save the file as, for example, part.step.
7. Open the exported STEP file in the recipient's software, or re-import it into SOLIDWORKS, and check body count, holes, faces, dimensions, colors, and orientation.

Before export, use Tools → Evaluate → Check to find invalid faces, short edges, and other geometry defects. If a re-imported STEP model has gaps or failed faces, use Tools → Evaluate → Import Diagnostics to assess and repair translated geometry where possible.

Alternative desktop and online tools

If SOLIDWORKS is unavailable, CAD Exchanger Desktop is a practical independent translator for many SOLIDWORKS part versions and can export STEP. Check its current SLDPRT version-support matrix before relying on it for production data. Autodesk Fusion can also import supported SOLIDWORKS part files and export STEP, but its translation workflow and supported versions depend on the current Fusion release and service settings.

For occasional browser-based conversion, CAD Exchanger Cloud and Onshape can import supported SOLIDWORKS files and produce STEP exports. Do not upload export-controlled, customer-confidential, medical, defense, or otherwise sensitive models until the service's retention, access, processing-location, and security terms have been approved.

FreeCAD is not a dependable primary choice for native .sldprt conversion: standard FreeCAD installations do not provide a full native SOLIDWORKS translator. It may work through third-party translators or add-ons, but results and version support vary.

Compatibility limits to check

STEP does not preserve the editable SOLIDWORKS feature tree, sketches, equations, design tables, mates, or configuration rules. The recipient usually receives a non-parametric solid or surface model that can be measured, machined, referenced, and edited with direct-modeling tools.

Set the intended document units before export through Tools → Options → Document Properties → Units. STEP carries unit information, but an incorrect import-unit setting can still cause a receiving application to display the model at the wrong scale.

For multibody parts, verify that every required body is present after import. Some systems retain multiple solids as separate bodies; others may require a single merged solid. Ask the recipient for the required STEP protocol, unit system, and whether colors, product-manufacturing information, or separate bodies must be retained.