Regarding drilling, ultrasonic-assistance enables various potentials such as less tool wear, enhanced chip breaking and burr reduction. Although there are many technological studies verifying these advantages, no theory for process behaviour, design and parameter evaluation is available. Thus, this paper presents a kinematic analysis of the interaction between tool and workpiece to contribute to overall process understanding. Specific process scenarios are classified and characteristic parameters for the evaluation and design of ultrasonic-assisted drilling are determined. In addition, experimental investigations based on the developed process model are carried out analysing chip shape, bore surface and process stability acquired by acoustic measurements. The kinematic analysis shows the classification of ultrasonic-assisted drilling according to continuous and intermitted cutting conditions. In addition, the superposition of ultrasonic vibrations causes a modulation of uncut chip thickness related to the ratio of ultrasonic frequency and spindle speed. In general, experimental results show that ultrasonic-assisted drilling is leading to shorter chips. While using parameters for intermitted cutting conditions needle chips occur. At the same time, intermitted cutting conditions induce process instabilities identified using the acoustic measurement approach.

Due to continuous tool engagement, turning processes tend to form long chips when machining ductile materials. These chip shapes have a negative influence on process performance and productivity. One approach to improve chip breakage is superimposition of vibrations in feed direction of the turning process, which leads to a modulation of uncut chip thickness. In a joint industrial project with Schaeffler Technologies AG & Co. KG, Fraunhofer IWU developed an oscillating actuator for turning. The actuator converts a rotational movement of a drive motor into a translational vibration via an eccentric gear. The tool shank is mounted in solid joint assemblies. With this prototypical system, a cyclic movement of the tool in feed direction can be realized. The typical operating parameters of the actuator is within the range of 1...100 Hz with adjustable vibration amplitudes up to 0.6 mm peak-to-peak. A significant improvement in chip breaking during the machining of steel 1.0503 was shown in cutting tests.

Cutting forces in turning processes usually correlate with tool conditions. For this reason, the acquisition of force signals is of key importance for monitoring purposes. Despite the robustness of current piezoelectric measuring platforms, their large weight ratio relative to standalone tool-holder systems limits their effective usable bandwidth for analyzing force signals. Further limitations include high costs and lack of flexibility for general purpose turning operations. Due to this, such systems fail to find acceptance in practical applications and are mainly limited to research activities. To improve these aspects, this work investigates the use of an alternative integration concept using a piezoceramic thick film sensor for performing near-process cutting force measurements at the tool-holder. The charge output of the sensor was estimated using a coupled structural-piezoelectric simulation for its design. The modelled prototype was assembled and characterized by means of a static calibration and an impact hammer test. Following these, a first implementation of the system under dry cutting conditions took place.

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