Dimensional Accuracy and Measurement Variability in CNC-Turned Parts Using Digital Vernier Calipers and Coordinate...

Area of Science:

• Manufacturing Engineering
• Metrology
• Materials Science

Background:

• Dimensional accuracy in CNC machining is critical for high-precision manufacturing.
• Materials with varying mechanical and thermal properties pose challenges for measurement.
• Existing metrology systems require experimental validation for diverse engineering alloys.

Purpose of the Study:

• To experimentally compare manual (Digital Vernier Caliper - DVC) and automated (Coordinate Measuring Machine - CMM) metrological systems.
• To assess measurement accuracy, error, and repeatability across five engineering alloys and five machined zones.
• To investigate the influence of material properties and machining on measurement performance.

Main Methods:

• Experimental comparison of DVC and CMM on five engineering alloys (e.g., Aluminum 6061, Stainless Steel 304).
• Measurement of absolute error, relative error, standard deviation, and repeatability across five axial zones.
• Principal Component Analysis (PCA) and multivariate modeling to analyze measurement-property relationships.

Main Results:

• DVC performance is sensitive to operator input and surface irregularities, showing higher errors and poor repeatability.
• CMM demonstrated superior precision and consistency, with significantly lower standard deviations and relative errors across all alloys.
• PCA identified distinct error sensitivities between manual and automated methods, enabling material classification by metrological reliability.

Conclusions:

• CMM is recommended for high-precision applications (aerospace, biomedical) requiring tight tolerances and reliability.
• DVC can be used as an auxiliary tool for less critical measurements, acknowledging its limitations.
• The study provides a framework for intelligent metrology selection aligned with Industry 4.0 requirements for accuracy and data-driven quality assurance.