CNC Machining Tolerances: A Comprehensive Guide
Understanding standard and tight tolerances in CNC machining, including tips for achieving precision in complex parts.
What Are Machining Tolerances?
Tolerances define the acceptable range of variation in a part dimension.
In CNC machining, understanding and specifying correct tolerances is critical for both quality and cost.
Standard Tolerance Grades
| Grade | Tolerance Range | Typical Application |
| IT6 | ±0.005mm | Precision bearings |
| IT7 | ±0.010mm | Gears and shafts |
| IT8 | ±0.020mm | General machining |
| IT10 | ±0.050mm | Rough machining |
Tips for Achieving Tight Tolerances
1. Select appropriate tooling and fixturing
2. Control thermal expansion through coolant management
3. Implement in-process measurement and feedback
4. Consider material properties and their effect on machinability