Measurement Terms

Centering/Leveling

What is Centering/Leveling?

• Centering/Leveling refers to the adjustment process required to align the rotation axis of a roundness measuring machine with the center axis of the object being measured. This step is critical before beginning any measurement (Figure 1).
  
  Centering: Ensures that the center of the object’s axis aligns perfectly with the rotation axis of the machine.
  
  Leveling: Ensures that the axis of rotation is parallel to the object’s central axis, preventing tilts that could distort measurements.
  
  
• The adjustment process depends on the specific roundness measuring machine being used. Some models feature support functions that display the required adjustment values, while others perform these adjustments automatically. Proper alignment is essential to achieving accurate and reliable measurement results (refer to Figure 1 for an example of the impact of insufficient centering adjustment).

Figure 1

When Centering Adjustment is Insufficient

• Insufficient centering adjustment can result in measurement errors caused by eccentricity, making proper adjustment essential.
  
  
• For example, if a cross-section with perfect roundness (0 μm) at a diameter of Φ5 mm is measured with eccentricity:
  
  An eccentricity of 10 μm results in a roundness error of 0.02 μm.
  
  An eccentricity of 100 μm results in a roundness error of 2 μm.
  

Figure 2

When Horizontal Alignment Adjustment is Insufficient

• Insufficient horizontal alignment adjustment can cause the measured cross-section to appear as an ellipse, leading to inaccurate roundness measurements. Proper horizontal alignment is essential to ensure precision.
  
  
• For example, if a cross-section with perfect roundness (0 μm) at a diameter of 50 mm is measured while inclined:
  
  An inclination of 0.1° results in a roundness error of 0.03 μm.
  
  An inclination of 0.7° results in a roundness error of 2 μm.
  

Figure 3

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