Evaluation of an experimental modal analysis device for micromilling tools

Stable machining conditions in the micromilling process are critical to increase the production of small components. Precise frequency response measurements are essential to generate the stability diagrams. Therefore, impact hammer application which mostly relies on operator’s skill and experience is very time-consuming and can produce imprecise results. This study aims to analyze a device developed to perform the experimental modal analysis of micromilling tools. The device facilitates the positioning of a fixed point Laser Doppler Vibrometer (LDV) as well as providing automatic and reproductive impact tests. Two mirrors supported by kinematic mounts are used to position the laser beam on the micro milling tool surface. The impact hammer is composed of a force sensor attached to a custom designed flexure-based body, in which an automated electro-magnetic releases the mechanism. A set of experiments were conducted to perform the precision positioning of the laser beam and the impact hits. The impact force repeatability in terms of the magnitude and impulse duration were also investigated. The application of the device was demonstrated through modal testing of two micromilling tools with two different diameters.