Grzegorz Kmita

Dr. Grzegorz Kmita


Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 August 2024 in Metals
Verified
Journal Article
Open access
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WMWitold Malec
Witold Malec
JKJoanna Kulasa Barbara Joanna Kulasa
Joanna Kulasa Barbara Joanna Kulasa
ABAnna Ewa Brudny
Anna Ewa Brudny
AHAnna Hury
Anna Hury
BABartlomiej Adamczyk
Bartlomiej Adamczyk
Andrzej RybakAndrzej Rybak
Andrzej Rybak
This article presents a comparative analysis of the crucial physical properties of electrically conductive components made of pure copper, produced by various additive manufacturing technologies such as binder jetting (BJ) and direct metal laser sintering (DMLS). The comparison concerned the assessment of critical parameters important from the application point of view, such as: electrical conductivity, hardness, yield point, microstructure and the occurrence of internal material defects. Same-sized components made in a conventional casting and subtractive method (machining) were used as a reference material. Comprehensive tests and the comparison of a wide range of parameters allowed us to determine that among the selected methods, printing using the DMLS technique allowed for obtaining arcing contact with mechanical and electrical parameters very similar to the reference element. Therefore, the obtained results showed the possibility of using the copper elements made by additive manufacturing for the switching and protection devices used in electrification and energy distribution industrial sectors.

28 June 2024 in Polymers
Verified
Journal Article
Open access
PDF file
JNJolanta Nieroda
Jolanta Nieroda
GKGrzegorz Kmita
Grzegorz Kmita
MKMichał Kozupa
Michał Kozupa
SPSzymon Piela
Szymon Piela
Andrzej RybakAndrzej Rybak
Andrzej Rybak
The constantly evolving electrification also entails an increase in requirements for the effective and efficient distribution of electricity with the lowest possible power losses. Such needs can be met by highly effective electrical devices, and one of them is a transformer whose main component is a magnetic core. Currently, one of the soft magnetic materials used alternatively for the production of transformer cores are amorphous metal strips with competitive losses. However, to successfully use these materials, a key problem must be solved: limited mechanical stability. The presented article describes the development and application of a polyimide-based binder for efficient bonding of an amorphous metal ribbon. The layered binder was characterized using confocal microscopy, scanning electron microscopy and Raman spectroscopy, and its anticorrosion and mechanical properties were examined. As a final step, a prototype of a toroidal magnetic core bonded with the binder was manufactured and subjected to the evaluation of no-load loss and the analysis of the emitted noise. It was confirmed that the proposed polyimide binder tremendously improved the mechanical stability while reducing core losses and audible noise.

24 October 2024 in Polymers
Verified
Journal Article
Open access
PDF file
Andrzej RybakAndrzej Rybak
Andrzej Rybak
RJRadek Javora
Radek Javora
RSRobert Sekula
Robert Sekula
GKGrzegorz Kmita
Grzegorz Kmita
Additive manufacturing offers great potential for various industrial solutions; in particular, the binder jetting method enables the production of components from various materials, including sand molds for casting. This work presents the results of an extensive set of experiments aimed at enhancing the structural strengthening of 3D-printed sand molds. Structural strengthening was achieved by impregnating the sand-printed structures with two polymer materials: epoxy resin and silicone varnish. Impregnation was performed with variable parameters, such as temperature, pressure, and time. Structural strengthening using polymers was investigated by analyzing the flexural strength and impact resistance of the impregnated products and comparing these obtained values with the reference material in terms of impregnation parameters and the polymer used. Microstructural observations and an analysis of the pore filling were also performed. This approach allowed for a full assessment of the influence of processing parameters and the type of polymer used for impregnation on the properties of sand-printed structures, which allowed for identifying the most optimal method to be used to strengthen the sand molds for casting the components for electrical devices. As a direct proof of concept, it was shown that impregnation with polymeric materials could effectively strengthen the sand mold, increasing its flexural strength and impact resistance by over 20 times and 5 times, respectively. A full-scale mold was printed using binder jetting, impregnated with epoxy resin at 65 °C, and used to successfully fabricate a fully functional electrification device.

6 May 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
JNJolanta Nieroda
Jolanta Nieroda
GKGrzegorz Kmita
Grzegorz Kmita
MKMichał Kozupa
Michał Kozupa
SPSzymon Piela
Szymon Piela
Maciej SitarzMaciej Sitarz
Maciej Sitarz
Andrzej RybakAndrzej Rybak
Andrzej Rybak
The ongoing electrification process also requires improvements in the efficiency of power transmission devices, such as transformers, the main part of which is the magnetic core. Despite great progress in the development of core material, losses and audible noise during their operation is still a critical issue to be solved. Currently, a magnetic material used to produce the transformer core is amorphous steel, which is gaining popularity. Compared to traditionally used grain-oriented silicon electrical steel, a significantly larger number of very thin amorphous ribbons is needed to produce the core, which is due to the fact that they are about an order of magnitude thinner, making mechanical stability a challenge. The presented article describes the preparation of a hybrid binder for amorphous steel based on the two types of silanes, tetraethyl orthosilicate and 1,2-bis(triethoxysilyl)ethane, for which their anticorrosive character and good dielectric properties were confirmed. Using the obtained binders, model toroidal cores were produced and their magnetic and acoustic properties were tested. The obtained results indicate that the applied silane-based hybrid binders improved important functional properties by reducing the magnetic no-load losses and audible noise.