What is an RFQ in manufacturing?
An RFQ (Request for Quotation) is a document sent to suppliers to request a price and lead time for manufacturing parts. In CNC machining, the quality of your RFQ directly affects the accuracy of the quotation you receive.
A complete RFQ reduces follow-up questions and helps suppliers provide more accurate pricing.
Suppliers often receive incomplete RFQs. A well-prepared RFQ stands out and receives more attention from engineering teams.
What to include in a CNC RFQ
- 2D drawing — PDF or DWG with critical dimensions, tolerances, and notes
- 3D CAD file — STEP or IGES format (STL is not sufficient for machining)
- Material specification — grade and condition (e.g., 6061-T6, 304 stainless)
- Quantity — prototype, small batch, or production volume
- Tolerances — critical dimensions and general tolerance standard
- Surface finish — required finish or cosmetic requirements
- Secondary operations — anodizing, plating, heat treatment, etc.
- Packaging and delivery requirements
Include a general tolerance note like "ISO 2768-m" to avoid specifying tolerance on every dimension. This reduces drawing clutter.
Recommended file formats
| File type | Recommended format | Why |
|---|---|---|
| 3D CAD | STEP (.stp) or IGES (.igs) | Universal format, preserves geometry |
| 2D drawing | Easy to view, preserves annotations | |
| Native CAD | SLDPRT, X_T | Acceptable if supplier uses same software |
| STL | Avoid for quoting | Does not preserve tolerance or surface data |
Sending only an STL file. STL files approximate surfaces and do not include tolerance or material information needed for accurate quoting.
How to specify tolerances effectively
- Use a general tolerance note for non-critical dimensions
- Call out specific tolerances only where required
- Avoid applying tight tolerances to every dimension
- Specify GD&T symbols for form and position control when needed
How to evaluate supplier responses
- Price — is it within your budget? Compare multiple quotes
- Lead time — does it meet your schedule?
- DFM feedback — did the supplier suggest improvements?
- Communication — was the response clear and professional?
- Quality approach — did they ask about inspection and quality requirements?
Frequently Asked Questions
What file format is best for CNC RFQs?
STEP (.stp) is the most universal format. It preserves geometry and is supported by most CAD systems.
Should I include tolerances in my RFQ?
Yes. Include both a general tolerance standard and specific tolerances for critical dimensions.
How long does a CNC RFQ typically take?
Most suppliers respond within 24-48 hours for simple parts. Complex parts may take longer.
Can I get a quote without a 2D drawing?
Yes, but it will be less accurate. A 3D CAD file alone does not communicate tolerances or finish requirements.