Most Indian engineering factories accept PDF, DWG and STEP files. The safest package is a dimensioned PDF drawing as the controlling document, plus a STEP model so the factory can plan tooling and write CNC programs.
Smaller workshops may only work from a printed drawing. Larger exporters usually have CAD and CAM software and can open common formats. Ask before you send, rather than assume.
If a factory cannot open your 3D file, it is not always a reason to drop it. Many good conventional workshops work only from 2D drawings. But for complex shapes, 5-axis work or CNC programming, a factory that can import STEP files will make fewer errors.
What each format is for
- PDF is the formal drawing with dimensions, tolerances, notes and the revision block, and everyone can open it.
- DWG or DXF is a 2D CAD format that is useful for profiles, sheet metal and laser or plasma cutting.
- STEP is a neutral 3D format that almost every CAD and CAM system can import.
- IGES is an older neutral 3D format, still accepted but less reliable for solid models.
- Native files from your own CAD system are useful only if the factory runs the same software and version.
Which file controls
Decide which document controls if the files disagree. In most cases the 2D drawing should control, because it carries the tolerances, surface finishes and notes. A 3D model shows the nominal shape but usually not the tolerances.
State this on the drawing or in your purchase order. A short note such as "2D drawing governs; 3D model for reference" avoids a dispute later. If you use model-based definition with tolerances in the 3D file, tell the factory clearly and check that its software can read them.
Units, standards and revisions
Indian factories work mainly in metric units. Inch drawings are fine, but say so clearly and keep units consistent across files. Mixed units on one drawing cause errors.
Use the projection symbol on every drawing. First-angle projection is common in India and Europe, while third-angle is common in North America. A part made from a misread view can be a mirror image of what you need.
Control revisions carefully. Put the revision letter in the file name and the title block, and send a short list of changes with each new revision. Ask the factory to confirm which revision it is working to. Old revisions in circulation are a common cause of wrong parts.
Sending files safely
Use a shared folder with access you can withdraw, rather than loose email attachments. Mark drawings as confidential. Our guide on protecting drawings and designs covers agreements and practical steps. For what else to include with the files, see what to send for an engineering quote.
Next step
We check that the factory can read your files and is working to the right revision. Book a free sourcing review.