Development of On-Machine System for Measurement of Workpiece Substrate Properties and Topography
Résumé
Commercially available nanoindentation testers are often limited to planar specimens only a few millimeters thick. They are also highly sensitive to vibration. In this study, a vibration tolerant indentation system that can be mounted inside a 5-axis machine is proposed which eliminates restrictions on specimen thickness and shape. The drive unit contains a piezoelectric actuator that stretches and pushes on the center of a flexure when a voltage is applied. A diamond indenter is mounted on the load-cell and placed at the tip of a cylindrical member, which is itself fixed to the flexure. A displacement sensor is attached next to the indenter and measures relative displacement to the specimen surface. Compliance of the system was compensated by signal processing, after which comparison of measurement results against a commercial testing device showed overall agreement on the hardness and Young's modulus across various metal specimens. Future practical changes are also proposed to improve the measurement performance.