Convert IGS to PRT

A receiving CAD system may require a native part file for feature editing, assembly work, or design-history access instead of the neutral IGS format. Converting the geometry to the target system’s .prt format makes it usable there, but it does not recreate the original parametric model.

What IGS contains

IGS, usually identified by .igs or .iges, is the file extension for IGES (Initial Graphics Exchange Specification). It is a neutral CAD exchange format used by mechanical designers, manufacturers, suppliers, and engineering software to transfer wireframes, curves, surfaces, and sometimes trimmed or solid geometry between different CAD systems.

IGES normally transfers geometry rather than the source application’s feature tree, constraints, parameters, sketches, materials, or assembly history. An imported model therefore often appears as an unstructured collection of surfaces or as a single imported feature.

What PRT means

.prt is not one universal CAD format. PTC Creo and its predecessor Pro/ENGINEER use .prt for native part files, while other systems, including Siemens NX, also use the extension for their own incompatible part formats. The extension alone does not identify which program can open the file.

A native Creo PRT can preserve Creo-specific features, parameters, references, and downstream editing capabilities when the model was created natively. It may also integrate correctly with Creo assemblies and drawings. These advantages apply only to the destination system’s PRT format; converting IGES cannot recover design history that was never present in the IGES file.

Convert IGS to a Creo PRT file

Use PTC Creo when the required output is a native Creo or Pro/ENGINEER part:

1. Start Creo and choose File → Open.
2. Set the file type to IGES, then select the .igs or .iges file. Check the import units and import options before confirming.
3. Inspect the imported geometry. Use Import DataDoctor to find gaps, bad trims, sliver faces, and other failed connections, then heal or replace the affected surfaces.
4. Confirm that the result forms the required solid. If Creo imports only surfaces, repair the boundary and create a solid before saving.
5. Choose File → Save As, select the Creo part format, and save the file with a .prt extension.
6. Reopen the saved file in Creo and check mass properties, critical dimensions, datum references, and any features required by the receiving workflow.

The imported geometry may remain an import feature rather than a normal, editable sequence of Creo extrusions, rounds, holes, and sketches. If feature-level editing is required, remodel the important features after import or use Creo’s feature-recognition tools where appropriate.

Use the destination CAD system when PRT means something else

If the recipient uses Siemens NX, perform the import and save operation in NX instead of Creo. NX’s .prt files are not interchangeable with Creo PRT files. Confirm the required application and release before conversion because native files can be version-dependent.

Other CAD programs may use different native extensions, such as .CATPart for CATIA and .ipt for Autodesk Inventor. A converter that merely changes the filename to .prt does not create a valid native part file.

Online and alternative conversion services

There is no generally reliable online service that converts arbitrary IGES geometry into a valid, editable Creo PRT file. Native PRT generation depends on the destination CAD kernel, application version, import settings, and geometry repair. Use Creo or the relevant vendor’s CAD software for this target.

Reputable cloud CAD services such as CAD Exchanger can be useful for inspecting IGS files or converting them to supported neutral formats such as STEP when the recipient does not specifically require PRT. Those services do not make a STEP file equivalent to a native Creo part, and cloud upload may violate confidentiality requirements. Do not use a generic online renamer or an unverified converter for engineering data.

Quality and compatibility checks

• Units: IGES unit metadata can be missing or misinterpreted. Compare a known dimension after import and correct the units before saving.
• Topology: Gaps, self-intersections, tiny faces, and faulty trims can prevent a watertight solid. A visually complete model may still fail volume or manufacturing operations.
• Data loss: Feature history, constraints, colors, layers, attributes, tolerances, and assembly relationships may be absent or altered. IGES drawings and annotations also have limited interoperability.
• Geometry type: Curves and surfaces may import correctly even when a solid does not. Verify that the receiving application recognizes the intended solid bodies.
• Accuracy: Healing and tolerance changes can modify edges or surfaces. Recheck interfaces, hole sizes, mating faces, and mass properties against the source.
• File size: A native PRT may be smaller or larger than the IGS file; size depends on topology, feature history, compression, and the CAD system.