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1

The influence of cutting parameters and tool wear on the quality of holes in package sheets used in heat exchangers

Wieczorek Łukasz, Józwik Jerzy, Niesłony Piotr, Moj Kevin

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 4

156--170

EN

The presented research aimed to obtain information on the effect of cutting parameters and tool wear on the quality of shaped holes in stainless steel package sheets. The testing was planned to allow evaluation of the impact of drilling technology. For this reason, verification tests were performed on a monolithic sheet of the same material grade and thickness equal to the package of four base sheets. It was noted that the double-insert drill is not qualified for use in this process, as it does not provide adequate hole quality (even 0.7 mm deviation in measured diameter from nominal value) and does not provide the expected tool life. Significantly better results were obtained for the monolithic and indexable head drills (IT8). In addition, it was observed that the burr formed when the drill exits the hole, in the case of the indexable double-insert drill, is also significantly larger (~1mm) than for the other tools (less than 0.1 mm). Preliminary tests carried out in this way made it possible to select the tool with the best cutting capability and quality of the generated holes. It was decided to use a drill with an interchangeable head. Tests have shown that it is possible to produce up to 1,000 holes with a diameter of 18.5 mm in a sheet package of 316Ti material with a thickness of 40 mm while maintaining the assumed effective speed of the process (n=1200 rpm, fn=0.18 mm/rev). In experimental testing, a significant effect of cutting speed on tool wear was noted. A correlation between coolant concentration and tool life was also identified - raising the concentration from 8% to 12% increased tool life by virtually 100%. Testing of hole roughness over a full tool life cycle showed that a drill bit with a completed break-in phase provides better hole roughness than a new drill bit. Measuring equipment and software were used for the research and processing of the results – Wenzel XO55, Hommel Etamic LV 17, WM Quartis R2021-1, Grapher 18.3.400, Autodsk Inventor Professional 2023.

2

Impact of measurement conditions and measurement strategy on the positioning accuracy and repeatability of the milling plotter

Sałamacha Daria, Józwik Jerzy

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 1

349--362

EN

The paper presents the test results of the accuracy and repeatability of the three-axis milling plotter with the use of the LSP 30 Compact laser interferometer. The experiment was carried out using two measurement strategies. A machine learning (ML) model was developed using feed rate vf and the positioning accuracy and repeatability parameters (A, A↑A↓, R, R↑R↓, B and B). Due to the nature of the data, a linear regression model was chosen. A less efficient but more accurate measurement strategy was the ´pilgrim´ strategy. Whereas, the linear measurement strategy proved to be more efficient but less accurate. High, constant insolation of the test stand and air humidity influenced the measurement results. The predicted positioning accuracy and repeatability parameters were determined on the basis of the developed model using first-degree regression equations. Prediction of positioning accuracy parameters depending on measurement conditions and measurement strategies can be a useful tool to control or predict the process machine accuracy and the shaped contour accuracy.

3

Fast approximation of matrix exponential and its application to independent component analysis problem

Mika Dariusz, Józwik Jerzy, Leccese Fabio, Ruggiero Alessandro

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 3

350--361

EN

Abstract: This paper introduces a new low-computational method for approximating the skew-symmetric and skew-Hermitian matrix exponential. Our method belongs to the splitting methods, which we modify and combine with new low-cost analytic formula for sparse skew-symmetric and skew-Hermitian matrix exponential, similar to the Euler-Rodrigues formula, well known for the skew-symmetric matrices in R^3. Our new approximation procedure for skew-symmetric (skew-Hertmitian) matrix exponential that we use is computationally very cheap, which ensures high speed of algorithms using this operation in their structure. To evaluate this approximation method we used it for the optimization problem of Independent Component Analysis (ICA) type. The results are compared to other known ICA algorithms such as well known Infomax and JADE. The average increase in convergence speed in the studied range of the number of source images was approximately 7% compared to the second fastest ICA algorithm using the standard and universal matrix exponential formula. High quality of separation was also obtained, comparable to well-known ICA algorithms such as Infomax or JADE.. Obtained results confirm the effectiveness of the proposed method in technical applications and indicate potential use in on-line applications.

4

Influence of steam sterilization and raster angle on the deflection of 3D printing shapes

Zaborniak Małgorzata, Budzik Grzegorz, Grzywacz-Danielewicz Katarzyna, Józwik Jerzy, Dziedzic Krzysztof, Magniszewski Marek, Rak Danuta

Polimery

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2024

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Vol. 69, nr 2

117--122

EN

The study examined influence of steam sterilization and the raster angle (0°, 90°) on the deflection of polymer shapes obtained by 3D printing. In the case of PEEK and PLA, the FDM/FFF method was used, in the case of photocurable resin, DLP technology, and in the case of MED610, PolyJet technology. It was shown that the raster angle, type of material and sterilization have a significant impact on the strength and deformation of the tested polymers. A model of a facial bone implant was also developed and the suitability of the tested materials for obtaining this type of implants was examined. The dimensional accuracy of the implant models was highest for the MED610 model. However, due to the significant deflection of this polymer under load, its use is only possible in areas of low stress. In the case of UV resin printed in the vertical direction (90°), the samples showed the least deflection and the printed model had no visible defects. The greatest deformations occurred at the ends and narrowing’s of the model.

PL

W pracy zbadano wpływ sterylizacji parą wodną oraz kąta rastra (0°, 90°) na ugięcie kształtek polimerowych uzyskanych metodą druku 3D. W przypadku PEEK i PLA zastosowano metodę FDM/FFF, dla żywicy fotoutwardzalnej technologię DLP, a MED610 technologię PolyJet. Wykazano, że kąt rastra, rodzaj materiału oraz sterylizacja mają istotny wpływ na wytrzymałość i odkształcenie badanych polimerów. Opracowano także model implantu kostnego twarzoczaszki i zbadano przydatność badanych materiałów do otrzymywania tego typu implantów. Dokładność wymiarowa modeli implantów była najwyższa dla modelu MED610. Jednak ze względu na znaczne ugięcie tego polimeru pod obciążeniem jego zastosowanie jest możliwe jedynie w obszarach o małych naprężeniach. W przypadku żywicy UV drukowanej w kierunku pionowym (90°) próbki wykazywały najmniejsze ugięcie, a otrzymany model nie miał widocznych wad. Największe odkształcenia wystąpiły na końcach i zwężeniach modelu.

5

Modeling of optimal probe measurement time on a machine tool using machine learning methods

Józwik Jerzy, Zawada-Michałowska Magdalena, Kulisz Monika, Tomiło Paweł, Barszcz Marcin, Pieśko Paweł, Leleń Michał, Cybul Kamil

Applied Computer Science

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2024

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Vol. 20, no. 2

43--59

EN

This paper explores the application of various machine learning techniques to model the optimal measurement time required after machining with a probe on CNC machine tools. Specifically, the research employs four different machine learning models: Elastic Net, Neural Networks, Decision Trees, and Support Vector Machines, each chosen for their unique strengths in addressing different aspects of predictive modeling in an industrial context. The study examines the input parameters such as material type, post-processing wall thickness, cutting depth, and rotational speed over measurement time. This approach ensures that the models account for the variables that significantly affect CNC machine operations. Regression value, mean square error, root mean square error, mean absolute percentage error, and mean absolute error were used to evaluate the quality of the obtained models. As a result of the analyses, the best modeling results were obtained using neural networks. Their ability to accurately predict measurement times can significantly increase operational efficiency by optimizing schedules and reducing downtime in machining processes.

6

Współczesne technologie wytwarzania w przemyśle lotniczym. Cz. II

Józwik Jerzy

Stal, Metale & Nowe Technologie

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2023

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nr 3-4

40--49

PL

W artykule przedstawiono i omówiono wybrane technologie wytwarzania stosowane w przemyśle lotniczym. Skupiono się na technologiach obróbki ubytkowej, szczególnie w przypadku kształtowania części konstrukcji statków powietrznych.

7

Predictive tools as part of decission aiding processes at the airport – the case of Facebook Prophet library

Korga Sylwester, Żyła Kamil, Józwik Jerzy, Pytka Jarosław, Cybul Kamil

Applied Computer Science

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2023

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Vol. 19, no. 4

51--67

EN

Prophet is a quite fresh and promising open-source library for machine learning, developed by Facebook, that gains some significant interest. It could be used for predicting time series taking into account holidays and seasonality effects. Its possible applications and deficit of scientific works concerning its usage within decision processes convinced the authors to state the research question, if the Prophet library could provide reliable prediction to support decision-making processes at the airport. The case of Radawiec airport (located near Lublin, Poland) was chosen. Official measurement data (from the last 4 years) published by the Polish Government Institute was used to train the neural network and predict daily averages of wind speed, temperature, pressure, relative humidity and rainfall totals during the day and night. It was revealed that most of the predicted data points were within the acceptance threshold, and computations were fast and highly automated. However, the authors believe that the Prophet library is not particularly useful for airport decision-making processes because the way it handles additional regressors and susceptibility to unexpected phenomena negatively affects the reliability of prediction results.

8

Impact of friction coefficient variation on temperature field in rotary friction welding of metals – FEM study

Łukaszewicz Andrzej, Józwik Jerzy, Cybul Kamil

Applied Computer Science

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2023

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Vol. 19, no. 3

17--27

EN

A mathematical model is presented for investigating the temperature field caused by the rotary friction welding of dissimilar metals. For this purpose, an axisymmetric, nonlinear, boundary value problem of heat conduction is formulated with allowance for the frictional heating of two cylindrical specimens of finite length made of Al 6061 aluminium alloy and 304 stainless steel. The thermo-physical properties of materials change with increasing temperature. It was assumed that the coefficient of friction does not depend on the temperature. The mechanism of heat generation due to friction on the contact surface with the temperature field of samples is considered. The boundary problem of heat conduction was reduced to the set of nonlinear ordinary differential equations at time t relative to the values of temperature T at the finite elements nodes. The numerical solution of the problem was obtained with the inverse 2nd order differentiation method implemented in COMSOL FEM system (finite element method), with time step ∆t=0.1 (s). The influence of various values of friction coefficient is presented.

9

Surface Texturing on a CNC Machine Tool Using a Laser

Józwik Jerzy, Dziedzic Krzysztof

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 1

160--172

EN

In the paper stages of the process of constituting a surface with the texture of the injection mold of a wheeled vehicle steering wheel using laser technology was discusses. During micromachining process with texturing there is a 5-axis CNC-controlled CNC machine TOOL LASERTEC 65 Shape used with a rigid monoBLOCK structure with Siemens 840D sl control, equipped with a fiber laser with a power of 100W, a wavelength of 1064 nm and a focal length of 181 mm. Processing technology was prepared using Autodesk Maya, Adobe Photoshop, Adobe Illustrator, NX9, Lastex v. 2.27.26 computer programs and machine tool control systems. Results of machining the steering wheel of a wheeled vehicle with a concentrated laser beam are discussed. Geometric structure of the surface after texturing was evaluated. Presented technology can be used to obtain the desired texture properties on the surface of the parts.

10

Microbiological Analysis of Coolant Used in Machining

Józwik Jerzy, Zawada-Michałowska Magdalena, Budzik Grzegorz, Legutko Stanislaw, Kupczyk Maciej Jan

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 2

206--214

EN

The subject of microbiological tests of coolants presented in the work is the cutting fluid (emulsifying oil) of Fuchs ECOCOOL 68 CF3. The liquid was taken from the tanks of three different numerically controlled machines (Lasertec 65, MillTap 700, CTX beta 1250 TC), used with different intensity. The five most characteristic and popular media were used in the study: nutrient agar - plain, TSA medium (tryptone-soy-agar), medium with dichloran, rose bengal and chloramphenicol, Sabouraud agar with Chloramphenicol, Czapka agar. The incubation time was dependent on the type of microorganisms. After the specified time, the plates inoculated on the medium were subjected to visual observations and under the Leica DM 500 microscope. As a result of the observation, the following types of microorganisms (fungi and bacteria) were detected: Aspergillus Niger Tiegh, Candida Albicans, Saphylococcus Aureus, Micrococcus Luteus and Escherchia Coli and Citrobacter Freundia. The assessments were made in fixed periods. The results are presented as a function of the intensity of the use of cutting fluids. Microbiological analysis of machining fluids will allow for optimizing the time periods of using coolants and will also contribute to the protection of the operator's health and indirectly "extending the life cycle" of the technological machine.

11

Geometrical Accuracy of Threaded Elements Manufacture by 3D Printing Process

Budzik Grzegorz, Dziubek Tomasz, Kawalec Andrzej, Turek Paweł, Bazan Anna, Dębski Mariusz, Józwik Jerzy, Poliński Przemysław, Kiełbicki Mateusz, Kochmański Łukasz, Oleksy Mariusz, Cebulski Józef, Paszkiewicz Andrzej, Kuric Ivan

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 1

35--45

EN

Additive processes allow for almost any manufacturing of screw-threaded joint elements. However, this requires knowledge of the geometrical relationships of a threaded itself and the strength of materials from which the screw-threaded joint is made. Thanks to the development of research models and conducting tests related to dimensional accuracy and surface roughness, it was possible to test the models made by MEX process of ABS-M30, PLA, ABS, PETG materials, and PolyJet process from RGD720 polymer material.In the case of measurements carried out on the MarSurf XC20 system, the internal and external thread profile was obtained.Measurements of the surface roughness of the printed models were made using the Taylor Hobson TalyScan 150 profilometer. Based on the obtained surface, following the ISO 25178-2 standard, selected parameters were determined.

12

Combined Effect of CrB2 Micropowder and VN Nanopowder on the Strength and Wear Re-sistance of Fe‒Cu–Ni–Sn Matrix Diamond Composites

Ratov Boranbay, Mechnik Volodymyr, Rucki Miroslaw, Gevorkyan Edwin, Kilikevicius Arturas, Kolodnitskyi Vasyl, Siemiatkowski Zbigniew, Umirova Gulzada, Chałko Leszek, Józwik Jerzy, Zhanggirkhanova Arailym, Chishkala Vladimir, Korostyshevskyi Dmytro

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 1

23--34

EN

The paper presents research results on the enhancement of diamond composites designed for tools application for mining industry, hard rocks cutting, able to withstand harsh conditions under heavy dynamical loads. In the present study, both CrB2 micropowder and VN nanopowder additives were used in proportions up to 5 wt.% and 6 wt.%, respectively, together with the basic matrix composition of 51 wt.% Fe, 32 wt.% Cu, 9 wt.% Ni, and 8 wt.% Sn. Addition of both components, CrB2 and VN, appeared to be ad-vantageous in proportion of 2 wt.% and 4 wt.%, respectively. This composition exhibited the highest relative density of 0.9968, better than that without additives. Similarly, the highest values of compressive strength Rcm and flexural strength Rbm were reached for the composite with the same percentage of CrB2 and VN. Compared to the composite with no addition of CrB2 and VN, Rcm improved by almost 70%, while Rbm by 81%. Additionally, the abovementioned additives enhanced the ability of the matrix to prevent the diamond reinforcement from being torn out of the composite, which is very important under harsh working conditions of the cutting tools. The presence of CrB2 micropowder and VN nanopowder promoted densification of the matrix and adhesion between the diamond grits and the Fe‒Cu–Ni–Sn matrix.

13

Application of Plasma Actuator with Two Mesh Electrodes to Active Control of Boundary Layer at 50 Hz Power Supply

Gnapowski Ernest, Pytka Jarosław, Gnapowski Sebastian, Józwik Jerzy, Tomiło Paweł

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 1

58--63

EN

Numerous studies are conducted to improve the flow in the boundary layer to ensure laminar flow and in particular to increase flight safety. A new solution used to improve the laminar flow is the plasma actuator. The classic configuration of DBD plasma actuators is commonly used with the asymmetric electrode system. The manuscript describes the results of tests with a plasma actuator. Experimental tests were carried out on the built model of the wing with the SD 7003 profile, a plasma actuator was mounted on the upper surface. In contrast to the commonly used solution with solid tape copper electrodes, the novelty in the described research in the manuscript is the use of a large GND electrode (covering 70% of the upper surface of the wing) and a HV mesh electrode. The use of a plasma actuator on the upper surface of the wing affects the air flow in the boundary layer as a result of air ionization. The tests were carried out for a supply voltage from V = 7.0 kV to 12 kV and Reynolds number, Re = 87500 to 240000, flow velocity during the tests in the tunnel was in the range of U = 5-15 m/s and the angle of attack α = 5 -15 degrees. On the basis of the results experimental tests, the percentage change in the lift coefficient was calculated for the switched on and off DBD system. The obtained results indicate a maximum 17% increase in the lift coefficient for the plasma actuator activated for air flow U = 5 m/s and angle of attack α = 5 degrees. In the remaining configurations, changes in the lift coefficient amounted to 4%.

14

Analysis of Torsional Strength of Pa2200 Material Shape Additively with the Selective Laser Sintering Technology

Bernaczek Jacek, Dębski Mariusz, Gontarz Małgorzata, Grygoruk Roman, Józwik Jerzy, Kozik Bogdan, Mikulski Piotr

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 2

12--24

EN

The purpose of the undertaken research work is to analyze the torsional strength of standard samples with a circular cross-section, produced additively using the SLS (Selective Laser Sintering) technique – sintering PA2200 polyamide powders. The studies conducted so far have not included a static torsion test, the results of which are crucial for parts such as machine shafts, hubs, couplings, etc. Hence the idea of conducting the research in question. The samples were made in different settings relative to the machine's working platform and subjected to post-processing in two variants – by water-soaking and furnace-heating – in order to determine the influence of the orientation of the model in the manufacturing process and the type of post-processing on torsional strength. The produced samples were additionally subjected to a preliminary dimensional and shape verification due to the significant impact of the accuracy of the models in the SLS process on the operation of the above-mentioned machine parts. Based on the analysis of the test results, it was found that the highest torsional strength was determined for the furnace-heated samples. In addition, the highest mapping accuracy was found for models positioned vertically in relation to the machine's working platform.

15

Strength of threaded connections additively produced from polymeric materials

Dziubek Tomasz, Budzik Grzegorz, Kawalec Andrzej, Dębski Mariusz, Turek Paweł, Oleksy Mariusz, Paszkiewicz Andrzej, Poliński Przemysław, Kochmański Łukasz, Kiełbicki Mateusz, Józwik Jerzy, Kuric Ivan, Cebulski Józef

Polimery

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2022

|

Vol. 67, nr 6

261--270

EN

The article presents the results of strength tests of screw-nut threaded connections made of polymeric materials such as: ABS, PLA, PET-G and acrylic resin. In order to make physical models, three 3D printing techniques were used: Fused Deposition Modeling (FDM), Fused Filament Fabrication (FFF), and PolyJet. The tests took into account the stresses caused by the axial force generated when the bolt is screwed into the nut or other structural element. Due to the complexity of the issue, the presented studies are only a starting point for further research.

PL

W artykule przedstawiono wyniki badań wytrzymałości połączeń gwintowych śruba-nakrętka wykonanych z materiałów polimerowych takich, jak: ABS, PLA, PET-G i żywicy akrylowej. Do wykonania modeli fizycznych stosowano trzy techniki druku 3D: FDM, FFF i PolyJet. W badaniach uwzględniono naprężenia spowodowane działaniem siły osiowej powstającej podczas wkręcania śruby w nakrętkę lub inny element konstrukcyjny. Ze względu na złożoność zagadnienia, przedstawione badania stanowią punkt wyjścia do dalszych badań.

16

Effect of Face Milling Parameters of Carbon Fiber Reinforced Plastics Composites on Surface Properties

Miturska-Barańska Izabela, Józwik Jerzy, Bere Paul

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no. 2

26--38

EN

This paper analyses the influence of face milling process parameters on the surface properties of carbon fibre reinforced polymer. The influence of milling speed and feed per tooth on the surface properties was determined. The influence of cutting speed and feed per tooth on surface energy properties was determined. The object of research was a carbon fiber reinforced plastics (CFRP) composites plate made of carbon fibre in epoxy matrix. The tool used in the study was a double-edged end mill. The machining parameters used were variable: cutting speeds of 100 m·min-1, 120 m·min-1, 140 m·min-1 and 160 m·min-1, and feeds per tooth of 0.015 mm/tooth, 0.020 mm/tooth, 0.025 mm/tooth and 0.03 mm/tooth. The axial depth of cut and radial depth of cut was a constant parameter. After milling, tests were carried out on the surface contact angle, which was used to determine the surface free energy. Based on the contact angle measurements carried out with the sitting-drop method and the calculation of the surface free energy with the Owens-Wendt model, it was observed, that the increase in the value of the surface free energy is significantly influenced by the increase in the cutting speed.

17

Dynamic Analysis of the Starting and Braking of the Table of CNC Machine Tool

Józwik Jerzy, Zawada-Michałowska Magdalena, Moń Damian

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no. 3

34--46

EN

The aim of the paper is a dynamic analysis of the starting and braking of the table of a numerically controlled CNC machine tool during idle motion. The experimental test was performed on the vertical table of the FV580A machining centre using the Phantom v1610 high-speed vision camera. The dynamics characteristics of the table movement were registered and the dynamics estimates of the movement were determined. The influence estimation of the parameters of the machine tool table motion on the value of the determined estimates was made. The results of measurements were discussed and guidelines and in order to minimise disturbances were formulated. The test results were summarised and discussed in the form of charts and tables. The directions of further research in the discussed subject area were also defined

18

Cutting Forces and 3D Surface Analysis of CFRP Milling

Biruk-Urban Katarzyna, Józwik Jerzy, Bere Paul

Advances in Science and Technology. Research Journal

|

2022

|

Vol. 16, no. 2

206--215

EN

Due to the wide application of Carbon Fiber Reinforced Polymer (CFRP) composites in various industries, more and more attention is paid to machining these materials. One of the most popular way of machining composites is the milling. Milling of composite materials (CM) is a difficult technology due to their anisotropic and heterogeneous structure and the fact that the reinforcing fibers have an intense abrasive effect on the tool edge during machining. The appropriate selection of technological cutting parameters as well as the type and geometry of the tool can significantly affect the value of cutting forces during milling and the quality of the surface after machining. The aim of the paper is to assess the influence of used tools (differing in the number of cutting edges) and various technological parameters of surface milling of CFRP composites on the cutting forces occurring during machining and on the surface quality after machining. Cutting forces were measured during the milling process on a special stand produced by Kistler and the roughness measurements and surface structure were analyzed using the Alicona InfiniteFocusG5 3D optical microscope. On the basis of performed research it was found that 14 edge tool gives lower values of Fx and Fy components of the cutting forces comparing to 2 edge tool, which is especially noticeable at higher cutting speed values vc=160 m/min, where the values of Fx and Fy components decreased by about 43% at fz=0.0030 mm/tooth. This tool gives also lower values of the Sa roughness parameter 1.65 µm.

19

2D Geometric Surface Structure ANN Modeling after Milling of the AZ91D Magnesium Alloy

Kulisz Monika, Zagórski Ireneusz, Józwik Jerzy

Advances in Science and Technology. Research Journal

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2022

|

Vol. 16, no. 2

131--140

EN

The paper presents the results of modeling 2D surface roughness parameters in milling by means of an artificial neural network (ANN). The AZ91D magnesium alloy was used. A HSS milling cutter was employed in the research. The main aim of the study was to obtain the lowest possible surface roughness (good quality) using a commonly available HSS cutter. The results of the research work were presented in the form of bar charts, surface charts and graphs depicting the quality of artificial neural networks. The conducted research shows that it is possible to carry out the machining processes that enable obtaining an average surface quality (defined by roughness parameters Ra, Rz, RSm, Rsk). The Ra, Rz, RSm parameters increase along with the machining parameters (fz, ap), as expected. The Rsk parameter takes (in most cases) negative values, which may indicate a surface with more intense friction and indicative of flat-topped distribution. On the other hand, the results of modeling the selected parameters – Ra, Rz, RSm – with the use of artificial neural networks allow concluding that the obtained network models show satisfactory predictive ability (R = 0.99), and thus are an appropriate tool for the prediction of surface roughness parameters.

20

Evaluation of changes in fuel delivery rate by electromagnetic injectors in a common rail system during simulated operation

Kamiński Mariusz, Budzyński Piotr, Hunicz Jacek, Józwik Jerzy

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 2

352--358

EN

The objective of this study was to determine changes in fuel delivery rate by common rail system injectors during their simulated operation on a test stand. Four Bosch injectors used, among others, in Fiat 1.3 Multijet engines were tested. The injectors were operated on a test rig at room temperature for 500 hours (more than 72 million work cycles). During the test, pressure and injection frequency were changed. Changes in the operating parameters were estimated based on obtained injection characteristics and effective flow area determined thereby. The observed changes in fuel delivery rate were compared with results of the surface analysis of control valves and nozzle needles. Despite the stated lack of wear, significant changes in the dynamics of injector operation were observed, particularly at short injection times. Small pilot injections cannot be corrected by the fuel injection control system because they do not affect the changes in torque; however, they do affect the combustion process. This creates conditions for increased emission of toxic exhaust components.