The accuracy of a CNC milling machine depends on several factors, including the machine's design, quality, age, and maintenance, as well as the material being machined and operating conditions. Here are some general guidelines for CNC milling machine accuracy:

Standard CNC Milling Machine Accuracy

• Typical positioning accuracy: 0.005 mm to 0.01 mm (0.0002" to 0.0004")

• Repeatability: 0.0025 mm to 0.005 mm (0.0001" to 0.0002")

• High-precision machines: Can achieve 0.001 mm (0.00004") or better

Factors Affecting Accuracy

1. Machine quality: More expensive, professionally-built machines generally offer better accuracy

2. Thermal effects: Temperature changes can cause expansion/contraction of machine components

3. Tool wear: Cutting tools degrade with use, affecting dimensional accuracy

4. Material properties: Some materials are more challenging to machine precisely

5. Vibration and rigidity: Machine stiffness affects the ability to maintain precision cuts

6. Control system: The quality of the CNC controller and feedback systems

Maintaining Accuracy

To maintain optimal accuracy:

• Perform regular machine calibration

• Keep the machine properly lubricated

• Use high-quality cutting tools and replace them as needed

• Control environmental conditions (temperature, humidity)

• Follow proper machine warm-up procedures

CNC mills provide more than adequate precision for most industrial applications, though extremely high-precision work may require specialized equipment or additional finishing processes.