Geometric Effects When Measuring Small Holes With Micro Contact Probes

Area of Science:

• Metrology
• Mechanical Engineering
• Precision Measurement

Background:

• Coordinate measuring machines (CMMs) are used for micro-feature measurement.
• Small holes (approx. 100 μm diameter) present unique measurement challenges due to small probe clearances.
• Geometric errors are magnified in micro-scale measurements.

Purpose of the Study:

• To identify and discuss critical error sources in CMM measurement of small holes.
• To highlight the impact of magnified geometric errors in micro-feature metrology.
• To provide insights into overcoming challenges in precise measurement of micro-scale components.

Main Methods:

• Analysis of geometric errors in CMM measurements of micro-holes.
• Investigation of probe-tip radius compensation effects.
• Examination of mechanical filtering impacts on measurement accuracy.
• Discussion of probe axis misalignment and non-orthogonality.

Main Results:

• Small clearances in micro-hole measurement amplify geometric errors.
• Probe-tip radius compensation and mechanical filtering become significant error sources.
• Misalignment and non-orthogonality of probe axes critically affect accuracy.
• Errors negligible in macroscopic measurements become dominant at micro-scale.

Conclusions:

• Standard CMM measurement assumptions are invalid for micro-features.
• Accurate micro-hole measurement necessitates addressing magnified geometric errors.
• Understanding probe-related errors is crucial for precision metrology of small features.