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Dry drilling of stainless steels under unstable conditions
Vrtání nerezových ocelí za sucha při nestabilních podmínkách
(Czech Technical University in Prague, 2026-07-16) Vávra, Petr; Pitrmuc, Zdeněk; Krátký, Jan
This diploma thesis summarizes the basic theoretical knowledge in the field of drilling, focusing on the effects of cutting conditions and drill geometry on cutting forces and thermal phenomena. It also covers the most commonly used tool materials and coatings for drilling steels. The experimental part deals with the selection of suitable tools for drilling turbine stator blade wheels made of X12Cr13 stainless steel for the purpose of blade fixation. It focuses on optimizing cutting conditions with respect to chip formation and process stability during dry drilling or drilling with the application of a small amount of lubricant. The final section addresses process optimization, the determination of cutting forces for the purpose of sizing the drilling machine spindle, and the practical verification of the process through the drilling of blade profiles.
Design of a System for Monitoring Process Parameters in Plastic Injection Molding
Návrh systému monitorování procesních parametrů při vstřikování plastů
(Czech Technical University in Prague, 2026-07-24) Jiránek, Jakub; Burian, David; Pospíšil, Pavel
This master thesis deals with the design of a system for monitoring process parameters in plastic injection molding. The theoretical part reviews the injection molding technology, process parameters, part defects and sensor methods for monitoring the process in the mold cavity. On this basis, a monitoring system with a pressure and temperature sensor in the mold cavity is designed and implemented on an experimental workstation. Measurements are carried out for polyethylene and polypropylene. Characteristic cycle parameters are calculated from the measured curves and their relationship to defect intensity is evaluated using ordinal logistic regression. Based on the results, the system design is refined and the possibilities of its use in industrial practice are assessed.
Design of a pallet exchange manipulator for milling machines
Konstrukce manipulátoru výměny palet pro frézovací stroje
(Czech Technical University in Prague, 2026-07-20) Kafka, Adam; Kolář, Petr; Šoustek, Pavel
This bachelor's thesis deals with the design of a manipulator for the automatic exchange of workpieces in a machining center. The work includes the design of structural sections of the manipulator, the choice of suitable motion systems and drives. Emphasis in placed on the competitiveness of the designed solution on the market. The last part includes calculations for the validation of chosen solutions.
Preparation and characterisation of diamond MEMS structures with optically active colour centres
Příprava a charakterizace diamantových MEMS struktur s opticky aktivními barevnými centry
(Czech Technical University in Prague, 2026-08-03) Doležal, Zdeněk; Aubrechtová Dragounová, Kateřina; Vanko, Gabriel; Kuliček, Jaroslav
Nanocrystalline diamond (NCD) is a promising material for microelectromechanical systems (MEMS) due to its exceptional mechanical, thermal, and optical properties. In particular, silicon-vacancy (SiV-) color centers enable non-contact optical temperature sensing based on temperature-dependent spectral shifts of their zero-phonon line (ZPL) and related full width at half maximum (FWHM). In this work, prototype diamond MEMS structures incorporating SiV- centers were fabricated and characterized. Selective growth of NCD was achieved by lithographic patterning and microwave plasma-enhanced chemical vapor deposition on Si/SiO substrates and on substrates with an additional Au/Ti layer, followed by wet etching to release suspended membranes and bridges. The fabricated structures were analyzed using scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and photoluminescence spectroscopy to evaluate the morphology of the diamond layer, determine its phase composition, and correlate mechanical strain and temperature with the optical response. The results revealed that mechanical strain significantly affects both the diamond Raman peak and the SiV- ZPL, making the separation of strain and temperature effects essential for reliable sensing. Completely released and mechanically relaxed structures exhibited the most stable temperature-dependent behavior, with a ZPL shift sensitivity of 0.017 nm K-1. These findings demonstrate the potential of SiV--doped diamond MEMS for contactless optical thermometry and strain sensing.
Preparation and characterization of diamond heterostructures
Příprava a charakterizace diamantových heterostruktur
(Czech Technical University in Prague, 2026-08-03) García Santomé, Daniel; Aubrechtová Dragounová, Kateřina; Szabó, Ondrej; Yatskiv, Roman
This thesis investigates the preparation and optoelectronic characterization of three diamond heterostructures containing silicon-vacancy centers. The studied devices were a lateral SiV/Au/glass structure fabricated on glass, a vertical BDD/SiV/n++-Si structure, and a vertical ZnO/SiV/BDD/Si heterostructure. Raman spectroscopy, photoluminescence spectroscopy, currentvoltage measurements, electroluminescence mapping, and hyperspectral imaging were used to evaluate their structural, optical, and electrical properties. Raman measurements confirmed the formation and preservation of nanocrystalline diamond in the investigated structures, together with contributions from grain boundaries, sp²-bonded carbon, boron-doped diamond, and ZnO. Photoluminescence measurements showed a clear emission band around 738740 nm, confirming the incorporation and optical activity of negatively charged SiV centers. The electrical response was strongly dependent on the device architecture. The BDD/SiV/n++-Si structure showed significant leakage and non-ideal transport, while the ZnO/SiV/BDD/Si structure exhibited the clearest rectifying behavior, particularly for an intermediate intrinsic diamond deposition time. SiV-related electroluminescence was detected in the ZnO-based structure under forward bias and in the lateral SiV/Au/glass structure under sufficiently high lateral bias. In the lateral device, the emission was localized near specific electrode regions and showed a strong polarity dependence, indicating an important influence of the gold-diamond interfaces and local electric-field distribution. Combined PL and EL measurements also demonstrated that the SiV emission can be modified by the applied bias, potentially through charge-state conversion, carrier trapping, and non-radiative processes. Overall, the ZnO/SiV/BDD/Si architecture provided the most promising performance for electrically driven SiV emission, although further improvements in interface quality, leakage suppression, and contact conductivity are required.