Bei BTA-Tiefbohrprozessen kommt es aufgrund der großen Werkzeuglängen häufig zu Torsionsschwingungen des Werkzeugsystems aus Bohrkopf und Bohrrohr. Im Vergleich zu konventionellen Stahl-Bohrrohren reduzieren Bohrrohre aus faserverstärktem Kunststoff diese Schwingungen durch ihr materialspezifisches Dämpfungspotenzial und erhöhen damit die Prozesssicherheit und verringern den Werkzeugverschleiß. Die Einbindung von Sensorfasern direkt in das Laminat erlaubt zudem eine Prozessüberwachung.   In BTA deep hole drilling, torsional vibrations of the tool system consisting of a drill head and a drill tube often occur due to the long tool lengths. Compared to conventional steel drill tubes, drill tubes made of fiber-reinforced plastic reduce these vibrations through their material-specific damping behavior and thus increase the process reliability and reduce the tool wear. The integration of sensor fibers directly into the laminate also allows a monitoring of the drilling process.

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For high-performance thermoplastic materials, material behavior results from the degree of crystallization and the distribution of crystalline phases. Due to the less stiff amorphous and the stiffer and anisotropic crystalline phases, the microstructural properties are inhomogeneous. Thus, imaging of the microstructure is an important tool to characterize the process-induced morphology and the resulting properties. Using focusing ultrasonic transducers with high frequency (25 MHz nominal center frequency) enables the imaging of specimens with high lateral resolution, while wave propagation is related to the elastic modulus, density and damping of the medium. The present work shows experimental results of high-frequency ultrasonic spectroscopy (HF-US) applied to injection-molded polyether-ether-ketone (PEEK) tensile specimens with different process-related morphologies. This work presents different analysis procedures, e.g., backwall echo, time of flight and Fourier-transformed time signals, facilitating the mapping of gradual mechanical properties and assigning them to different crystalline content and morphological zones.