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STEP vs IGES for CNC Manufacturing
Both formats can exchange geometry, but STEP is generally the more reliable starting point for modern solid-model CNC reviews.
Quick answer
STEP or IGES for CNC manufacturing
STEP is usually the stronger neutral exchange format for solid models and assemblies; IGES remains useful for legacy systems and surface data.
- Send the latest controlled model revision and identify the units
- Use a PDF drawing for tolerances, datums, finishes, threads and inspection notes
- The manufacturing team should verify imported geometry before quoting or machining
Buyer answers
Questions about CAD files for CNC review
Which neutral CAD format is normally preferred?
STEP is generally preferred for solid models and assemblies because it usually preserves solid geometry more reliably. IGES remains useful for legacy systems and surface data.
Does the CAD file replace the controlled drawing?
No. The drawing should carry tolerances, datums, threads, finishes, inspection notes and other requirements that are not fully defined by nominal geometry.
What should be checked before files are sent?
Confirm the latest revision, units, part orientation and included components. The receiving team should also verify imported geometry before quoting or machining.
Technical content reviewed: September 2026.
Why STEP is usually preferred
STEP commonly preserves solid bodies and assembly structure more consistently. It is easier to interrogate for volume, faces and manufacturable features than a collection of disconnected surfaces.
Where IGES can still be useful
IGES may be needed for older systems or surface-focused data. Imported surfaces should be checked for gaps, reversed faces and missing trims before quoting or programming.
The 2D drawing remains essential
A model rarely defines every tolerance, datum, thread, surface finish, coating, inspection instruction or revision note. Pair the 3D file with a controlled PDF drawing.
Before sending files
- Confirm units and revision
- Remove unrelated proprietary geometry
- Check that the exported body opens as expected
- Name the controlling model and drawing clearly
- Use the secure RFQ upload instead of a public media link
Review your actual part
Send the model, drawing and requirements for a manufacturing assessment.