CNC — Computer Numerical Control
Computer numerical control executes a programmed sequence of machine motion and auxiliary functions using a controller, feedback devices, drives and machine logic.
How CNC — Computer Numerical Control works
- Part programs command positions, feeds, speeds, tool functions and other machine actions.
- The CNC plans motion while servo drives and feedback devices move and monitor the axes.
- Machine-specific logic manages interlocks, tool changing, hydraulics, coolant and safety-related conditions.
- Control generation, installed options, memory, networking and service support shape the practical value of an older machine.
What to compare
| Control identity | Exact maker, model, series, software version and installed options. |
|---|---|
| Axes and channels | Controlled axes, simultaneous capability, spindles and multi-path support. |
| Programming | Supported cycles, macros, offsets, look-ahead and conversational features. |
| Connectivity | Program transfer, storage media, networking and data-interface capability. |
| Support | Parts, repair expertise, backups, documentation and parameter recovery. |
Used-equipment inspection checklist
Verify the machine
- Back up parameters, programs, offsets and machine logic where permitted.
- Confirm installed options on the control itself.
- Test program transfer and storage media.
- Review alarm history and battery status.
- Price obsolete displays, drives, boards and encoders before valuing the machine.
Verify the transaction
- Match the serial number and configuration to the seller's description.
- Identify every included and excluded accessory in writing.
- Confirm power, air, coolant, foundation, rigging and relocation requirements.
- Record a time-stamped operating demonstration and measured result.
- Price missing service, software, tooling and recommissioning before comparing offers.
Why this term matters in the used-machine market
Search results and listings often compress a complete production system into one label. Buyers should translate that label into capacity, condition, control generation, included tooling, serviceability and demonstrated output. Sellers improve credibility by disclosing those facts instead of repeating a brochure headline.
Market value is also specific to timing and buyer fit. A capable machine can trade poorly when its configuration is hard to relocate, support or redeploy; a common platform with documented maintenance, current controls and proven output may attract a wider buyer pool.
Related machine-tool terms
Frequently asked questions
Is CNC the machine itself?
No. CNC is the control system; a CNC machine is the complete mechanical, electrical and software system it directs.
Why does control generation affect resale?
It influences operator familiarity, program compatibility, serviceability, data transfer and the cost of recovering from electronic failure.
Sources and further reading
Source roles are explicit: linked organizations describe their own products, programs or technical guidance. The Machine Blue Book independently organizes and interprets that material for education and used-equipment due diligence. A citation is not an endorsement, sponsorship or guarantee.
- FANUC America — CNC Controllers, Controls and CNC Systems. Current CNC control families and milling/turning control functions. Reviewed September 26, 2026.
- IMTS — IMTS Technology Sectors. Primary classification of metal removal, quality, automation, software, tooling and workholding sectors. Reviewed September 26, 2026.
See the complete source register, research methodology and editorial standards.