Convert PRT to IGES

Some machining, inspection, and legacy CAD systems accept IGES but cannot open a native PRT file. Exporting an IGES copy lets external suppliers exchange geometry without installing the CAD system that created the original model.

What the PRT format is

.prt is not a single, standardized CAD format. In 3D modeling it most commonly identifies a proprietary part file from PTC Creo Parametric or Siemens NX; other CAD applications also use the extension for incompatible formats.

A Creo PRT can contain parametric features, sketches, relations, materials, and solid or surface geometry. An NX PRT can contain part data, modeling history, expressions, drafting data, and assembly references. These files are normally editable only in the application that created them, so identifying the source program and version is necessary before conversion. A text editor cannot reliably identify a proprietary PRT because it may be binary or use internal structures that are not self-describing.

What the IGES format is

IGES, stored as .igs or .iges, is a neutral CAD exchange format. It can represent wireframe entities, curves, trimmed surfaces, and, where supported by the translator, solid boundary-representation entities.

Its main benefit is compatibility with older CAD, machining, inspection, mold-design, and surface-modeling software. IGES does not preserve the native feature tree, sketches, parametric constraints, design history, assembly mates, or most application-specific metadata. If the recipient supports it, STEP is generally preferable for modern solid-model exchange; use IGES when the receiving system specifically requires it or handles its surface data better.

How to export from Creo Parametric

1. Open the PRT in the originating Creo installation or a compatible version that can read it.
2. Regenerate the model and resolve failed features. Confirm the displayed units and verify that the intended solid or surfaces are visible.
3. Choose File → Save As → Save a Copy.
4. Set the file type to IGES (*.igs, *.iges), specify the output name, and save.
5. In the IGES options, choose the representation required by the recipient. Use trimmed surfaces or a solid B-representation when supported; use wireframe only when required.
6. Set the export units explicitly and enable available geometry-checking or healing options. Menu names and options vary by Creo release.

How to export from Siemens NX

1. Open the PRT in NX and update the part so the displayed geometry is current.
2. Check units, reference sets, layer visibility, and the bodies or construction geometry selected for export.
3. Choose File → Export → IGES; the exact command name can vary by NX release and workspace.
4. Select the required bodies, faces, curves, or displayed objects, then set the output filename, units, and any available IGES representation or version options.
5. Export only the required bodies when the PRT contains multiple components. An NX assembly may otherwise produce separate component files or a multi-body result, depending on the export settings.
6. Open the result in the target CAD system or an independent CAD viewer and run its geometry check.

Using a dedicated converter

If the originating CAD application is unavailable, a commercial translator such as CAD Exchanger Desktop or Datakit CrossManager can be used only if its current compatibility list supports the specific Creo or NX PRT type and version. Import the file, select the required part or bodies, choose IGES as the output, set units and tolerance, and inspect the result. A translator cannot recover features that its PRT reader does not support.

Online services such as CAD Exchanger Cloud may be suitable for non-confidential files when their current documentation confirms support for the exact source format. Do not upload proprietary engineering data without approval: cloud processing can conflict with company security rules, export controls, or supplier agreements. Native desktop export is safer for confidential designs.

Quality and compatibility limits

This process translates geometry, not the original parametric design. Feature history, sketches, constraints, equations, appearance settings, assembly relationships, drawing annotations, and product metadata may be lost. The result may contain surfaces rather than a watertight solid, even when the source PRT contains a valid solid.

After export, check units, overall dimensions, body count, holes, fillets, surface normals, and gaps between adjacent faces. Reopen the IGES file in the destination system and use its sew, stitch, heal, or solidify tools when surfaces are fragmented or open. Unit mismatches and tolerance differences can change dimensions or prevent recognition of a closed solid.

Keep the original PRT and record the source application and version, export units, tolerance, selected bodies, and IGES settings. Request STEP instead when the recipient supports it and dependable solid transfer matters more than legacy compatibility.