Marian Jósko

The rise in resource consumption and environmental pressures are driving the development of a circular economy, in which the remanufacturing of machine and vehicle parts plays a significant role. Despite numerous studies on regeneration technologies (including additive manufacturing, cladding, and spraying), the literature lacks analyses concerning the non-destructive evaluation of the coating–substrate bond quality—when tested from the substrate side. The aim of this study was to evaluate the applicability of the ultrasonic method for the detection of defects (delaminations, detachments) in the adhesive joint between the regenerative coating and the base material. The study demonstrated that the ultrasonic method enables non-destructive, portable, and single-sided inspection of the integrity of the coating–substrate interface, making it a useful tool in industrial practice. Fifteen samples (including one reference sample) of varying thicknesses (from 1.9 µm to 1753.9 µm) were tested using ultrasonic probes with frequencies ranging from 1 MHz to 20 MHz. It was found that the adhesion of coatings approximately 74 µm thick can be estimated using an ultrasonic wave with a frequency of 1.66 MHz, whereas for coatings approximately 250 µm thick, adhesion can be estimated using higher frequencies, i.e., from 2.75 to 20 MHz.

The article discusses the issue of improving the management efficiency of spare parts at railway stations to reduce operational costs and enhance the effectiveness of rolling stock maintenance. A comparative analysis was conducted between traditional inventory storage strategies and models involving the redistribution of surplus spare parts between stations. For the quantitative assessment of the proposed approach, a mathematical model based on a multi-criteria decision analysis (MCDA) methodology was developed that includes the calculation of storage, transportation, and redistribution costs. The results show that redistributing spare parts reduces storage costs by 25%, while implementing the proposed strategy shortens the average downtime of railway wagons by 12.5%, confirming its economic feasibility. Moderate savings were achieved at the Zharyk and Zhanaaul stations, where excessive stockpiling of spare parts was reduced, and the main logistics hub—Karaganda Sortirovochnaya—helped minimize the risk of downtime. At the same time, the analysis revealed certain limitations, such as increased transportation costs and reduced network stability when redistribution volumes are high. The practical implications of the study lie in the potential implementation of the developed inventory management improvement model, not only for railway transport but also for other industries such as aviation and automotive logistics. Spare parts redistribution reduces the financial losses associated with frozen capital, increases the capital turnover, and decreases the risk of depreciation of stored components. The proposed approach ensures a more balanced distribution of resources between stations, facilitating an increase in the profitability of railway enterprises.

Ultrasonic nondestructive testing is widely used not only in the laboratory, but also in industry. The tests use various types of ultrasonic waves, diverse measurement techniques and different apparatus. One of the problems encountered is the high susceptibility of the surface wave to interference. Some of the interference is random in nature and can be minimized (e.g., contamination of the surface or resting a finger on the surface under study). Some of the interference is permanent in nature, such as variable surface roughness. The aim of the conducted research was to evaluate the influence of roughness on ultrasonic wave propagation. The study used samples with surface roughness Sa from 0.28 to 219 µm, and ultrasonic surface wave probes with frequencies from 1.41 to 8.02 MHz. It was observed that roughness significantly affects the attenuation of the ultrasonic wave, and the differences in signal amplification reached more than 15 dB. Similarly, the effect of the ultrasonic wave’s transit time through surfaces of different roughness was noted. It was found that the difference in the ultrasonic wave transition time was more than 50 µs. The results of the study can be helpful for the ultrasonic testing of materials with different surface conditions.

Ultrasonic nondestructive testing is widely used not only in the laboratory, but also in industry. The tests use various types of ultrasonic waves, diverse measurement techniques and different apparatus. One of the problems encountered is the high susceptibility of the surface wave to interference. Some of the interference is random in nature and can be minimized (e.g., contamination of the surface, resting a finger on the surface under study). Some of the interference is permanent in nature, such as variable surface roughness. The aim of the conducted research was to evaluate the influence of roughness on ultrasonic wave propagation. The study used samples with surface roughness Sa from 0.28 to 219µm, and ultrasonic surface wave probes with frequencies from 1.41 to 8.02 MHz. It was observed that roughness significantly affects the attenuation of the ultrasonic wave, and the differences in signal amplification reached more than 15dB. Similarly, the effect of the ultrasonic wave's transit time through surfaces of different roughness was noted. It was found that the difference in the ultrasonic wave transition time was more than 50 µs. The results of the study can be helpful, for ultrasonic testing of materials with different surface conditions.

Adhesive joints are some of the oldest inseparable connections, and were used much earlier than other non-separable connections (e.g., welded, soldered). Adhesives are widely used in the manufacture of vehicles, household appliances, aircraft, and medicine. One disadvantage of adhesive joints is their long bonding time (amounting, for example, to 72 h for polyurethane adhesives used in bus roof bonding), and another is their production of harmful waste. Tapes that are adhesive coated on both sides are increasingly being used to join parts during production. Such tapes have lower strength than traditional adhesives, but their bonding time is much shorter. In addition, the amount of waste remaining after production is minimized. Tapes, like adhesives, dampen vibrations well and seal the materials being joined. The purpose of this study was to evaluate the influence of selected factors on the quality of tape–steel sheet joints and to assess the possibility of testing acrylic tape–steel sheet joints using ultrasonic methods. It was found that the preparation of a surface for bonding has a significant effect on the quality of the joint, and it was confirmed that non-destructive evaluation of the quality of the tested joints by the ultrasonic method is possible. The decibel drop in the height of the first and fifth pulses obtained on the screen of the ultrasonic defectoscope was proposed as an ultrasonic measure. The highest-quality joints were characterized by a measure in the range of 12 dB, lower-quality areas of about 8 dB, and tape-free areas of about 5 dB. At the same time, it was noted that in the case of proper surface preparation, there was cohesive failure of the joint during breakage.

Adhesive bonding is widely used in modern industry. It has many advantages—the main one being the reduction in production costs. It also has certain limitations. One of the limitations of adhesive bonds is the relatively long bonding time of the joints. The main objective of this research was to determine the possibility of studying the kinetics of adhesive bond formation using a non-destructive ultrasonic method. A research experiment was planned and carried out. Adhesive specimens were prepared, and their quality changes over time were evaluated. In addition, the change in ultrasonic measures during the testing of these bonds was evaluated, as well as the hardness of the adhesive. In this study, the choice of test apparatus was made, in particular ultrasonic probes for the adhesive used and the materials to be bonded. The choice of adhesive was also made, for one in which bonding phenomena occur uniformly throughout the volume. This work examined the changes in the mechanical strength and hardness with time. The tests showed that the greatest changes in mechanical strength occur within the first 24 h after the bond was made. With the mechanical strength reaching 12.6 Mpa after 216 h, the strength in the first 24 h was 10.36 (for bonded steel sheets). For bonded steel discs, the maximum tensile strength was 26.99 Mpa (after 216 h), with a hardness of 22.93 Mpa during the first 24 h. Also, significant changes were observed in the adhesive hardness during the first 24 h. The hardness of the adhesive after 216 h was 70.4 Shore’a on the D scale, while after 24 h it was 69.4 Shore’a on the D scale. Changes in the ultrasonic parameters of the adhesive bond quality were found to occur along with changes in the bond quality.

Non-destructive ultrasonic testing can be used to assess the properties and condition of real machine elements during their operation, with limited (one-sided) access to these elements. A methodological question then arises concerning the influence of the material properties of such elements and the condition of their surfaces on the result of ultrasonic testing. This paper attempts to estimate the influence of material hardness and surface roughness on the result of such testing study area testing machine or plant components of unknown exact thickness. Ultrasonic testing was carried out on specially prepared steel samples. These samples had varying surface roughness (Ra from 0.34 to 250.73 µm) of the reflection surface of the longitudinal ultrasonic wave (the so-called reflectors) and hardness (32 and 57 HRC). The ultrasonic measures were the attenuation of the wave, estimated by the decibel drop in the gain of its pulses, and the propagation velocity of the longitudinal ultrasonic wave. Ultrasonic transducers (probes) of varying frequencies (from 2 to 20 MHz), excited by a laboratory and industrial defectoscope were used as the source of such a wave. The results of our research provide a basis for the recommendation of two considered ultrasonic quantities for assessing the material properties of the tested element. This is of particular importance when testing machines or plant components of unknown exact thickness and unknown roughness of inaccessible surfaces, which are the reflectors of the longitudinal ultrasonic wave used for testing. It has been demonstrated that by using the ultrasonic echo technique, it is possible to evaluate the roughness and hardness of the tested elements.

The article presents the results of ultrasonic testing of Ti6Al4V material produced by the conventional method and the laser bed fusion method. Modern manufacturing techniques, such as additive manufacturing, allow the production of parts with complex shapes. It is important to control the condition of such components throughout their lifetime. The purpose of this article was to determine the basic acoustic properties of Ti6Al4V material produced by two different methods—bar drawing and the additive manufacturing method. On this basis, an inspection scheme was developed for adhesive joints, the components of which are made by additive manufacturing technology. The decibel drops in the amplitudes of pulses reflected from the boundary of the adhesive-Ti6Al4V-AM and adhesive-Ti6Al4V joints were determined. The decibel drops for the connection of materials made with additive technology are higher than for the material made in a conventional way. The difference in decibel drop in the amplitudes of the additive manufactured material versus the drawn rod, depending on the ultrasonic head, can be up to 60%. The results of the study provide an important practical guideline for testing adhesive joints of parts made with additive manufacturing technology.

The technology and methods of testing the properties of varnish coatings used in motor vehicles are constantly and successfully developed. However, in the case of automotive varnish renovation coatings used in the repair of car bodies, the problem of fitting the quality of these coatings to the quality and current condition of the coating applied to undamaged vehicle components is not definitely solved. The main goal of the research was to determine the thickness and gloss distribution of the varnish coatings. The thickness and gloss of the varnish coating on the entire body of the vehicle were measured. Classical methods of assessing these properties were used. Defects in the renovation coating were also simulated, to show their negative impact on the varnish quality. The performed tests allowed for development of a procedure and algorithm for evaluation of the quality of the car’s renovation coating after the repair of the car body. The proposed procedure, expressed with the presented algorithm, allows to fit the obtained renovation coating to the quality and condition of the coating manufactured in factory on the car body in the range of its thickness up to 270 µm and gloss in the range of 5–90 GU. The developed procedure for the assessment of renovation coatings can be used in workshops that repair vehicle bodies. This will allow to improve the quality of renovation coatings and bring their properties, such as thickness or gloss, closer to those applied to the vehicle’s body at the factory.