1. Why CNC Machining RFQ Mistakes Matter
In CNC machining, quotation quality is directly tied to RFQ quality. Unlike standardized products, CNC parts are custom-manufactured, and every missing detail introduces uncertainty. When buyers make mistakes in RFQs, suppliers respond in predictable ways:- They delay quoting while asking clarification questions
- They add risk buffers to protect against rework or scrap
- They make assumptions that may not match buyer expectations
2. Mistake #1: Sending RFQs Without Proper Drawings
One of the most common mistakes buyers make is sending RFQs with:- No drawings at all
- Photos or screenshots instead of dimensioned drawings
- Outdated or revision-unclear files
3. Mistake #2: Not Defining Tolerances Clearly
Tolerances are one of the biggest cost drivers in CNC machining. When buyers omit tolerances or write “standard tolerance” without definition, suppliers must guess. Different suppliers may assume:- ISO 2768-f (tight)
- ISO 2768-m (medium)
- Shop-default tolerances
4. Mistake #3: Using Vague Material Descriptions
Writing “aluminum,” “steel,” or “plastic” is not sufficient for CNC machining RFQs. Material grade, condition, and availability significantly affect:- Material cost
- Machining strategy
- Tool wear
- Lead time
5. Mistake #4: Forgetting Quantity and Volume Planning
Suppliers price CNC machining very differently depending on quantity. Common RFQ issues include:- No quantity specified
- Prototype and production quantities mixed together
- No indication of future volume
6. Mistake #5: Over-Tolerancing the Entire Part
Applying tight tolerances to all dimensions is a hidden but very costly mistake. Over-tolerancing leads to:- Slower machining speeds
- More complex fixturing
- Higher scrap risk
- Longer inspection time
7. Mistake #6: Ignoring Surface Finish Requirements
Many buyers assume surface finish is “standard” unless specified. Suppliers do not. Surface finish affects:- Machining time
- Secondary processes (polishing, blasting)
- Post-processing costs (anodizing, plating)
8. Mistake #7: Not Specifying Inspection and Quality Scope
Inspection requirements can double or triple the effort for certain parts. Without clarity, suppliers may assume:- Visual inspection only
- Partial dimensional checks
- Full CMM inspection with reports
9. Mistake #8: Comparing Quotes Without Aligning Assumptions
Comparing CNC quotes without checking assumptions is one of the most dangerous buyer mistakes. Before comparing prices, confirm:- Same material grade
- Same tolerance interpretation
- Same surface finish
- Same inspection scope
- Same lead time
10. Mistake #9: Chasing the Lowest Price Only
The lowest quote often hides the highest risk. Extremely low prices may indicate:- Missing inspection
- Loose tolerance assumptions
- Unstable processes
- Limited quality control
11. Mistake #10: Not Asking for Manufacturability Feedback
Experienced CNC suppliers can often reduce cost or risk by suggesting small design changes. When buyers do not ask for DFM (Design for Manufacturability) feedback, they miss opportunities to:- Lower machining time
- Reduce setup complexity
- Improve yield
12. Conclusion
The quality of CNC machining quotes is a direct reflection of the quality of the RFQ. Most pricing problems can be traced back to buyer-side mistakes rather than supplier behavior. By avoiding these top 10 CNC machining RFQ mistakes, buyers can:- Receive faster and more accurate quotes
- Reduce pricing spread between suppliers
- Lower total manufacturing risk
- Build stronger, more transparent supplier relationships
