Michał Jakubowicz

Repeated use can alter the geometry and functional performance of orthopedic drill bits, yet geometry, process load, and hole dimensions are rarely tracked together. Four integrated commercial drill types—Stryker (3.2 and 3.5 mm), Synthes (4.5 mm), and Zimmer (4.3 mm)—produced successive through-holes in a 6 mm short-glass-fiber-filled epoxy cortical-bone analog at 900 rpm and approximately 40 mm/min. Projected point angle was measured intermittently, maximum thrust force and axial feed work were calculated per hole, and entrance diameter was measured optically. The primary estimand was longitudinal change within each drill type; the design was not factorial, and differences among types cannot be attributed separately to manufacturer, diameter, geometry, intended function, or alloy. Drill-type-specific models included fixed specimen intercepts. Force, work, and diameter were described using constrained monotonic functions selected by AICc, while trend inference used permutation-based Spearman tests. Point angle decreased significantly only for the Stryker drills. Force and work increased in every type, whereas entrance diameter decreased significantly for Stryker 3.5 mm, Synthes, and Zimmer. Pairwise force/work–diameter associations did not remain significant after adjustment for hole number and multiplicity. Repeated-use exposure therefore produced drill-type-specific mechanical and dimensional drift, but the study did not directly quantify cutting-edge wear or establish a causal material mechanism.

Flat leather belts were the first to be used in drive and transport technology and were later replaced by plastic belts. Recently, there has been a return to hybrid designs, where belts are constructed as a “sandwich” with a technical leather outer layer and a polyamide or TPU inner core. This study analyses the thermal behavior of a modern leather belt transmission as a function of braking torque at different rotational speeds of the active pulley. A linear temperature response was observed, with temperature differences between the passive and active belts of 4 °C at 500 rpm (R² = 0.93), 5.4 °C at 1000 rpm (R² = 0.96), and 4 °C at 1500 rpm (R² = 0.98). Due to the specific structure of the outer layer, non-contact surface measurement methods were applied. Surface topography analysis showed only minor changes in average roughness, with Sq = 37.8 µm (new belt) and 37.9 µm (used belt) and Sa decreasing from 26.5 µm to 25.1 µm. However, clear morphological changes were observed: Ssk decreased from 2.63 to 2.00, Sku from 14.3 to 8.19, Sp from 449 µm to 308 µm, and Sz from 557 µm to 400 µm, indicating reduced peak sharpness after wear. Profile parameters increased after operation, with Ra rising from 18.6 µm to 21.9 µm, Rq from 26.7 µm to 30.7 µm, and Rz from 116 µm to 143 µm. Microscopy confirmed wear-related smoothing and fragmentation of surface asperities. The results demonstrate that the applied methods are effective for evaluating thermal response and wear mechanisms in modern leather composite belts.

The production and assembly of large engineering structures, many requiring tight tolerances, demand accurate long-distance measurements. This poses a major challenge for metrologists across industries such as energy, aviation, automotive, and machinery. Contact measurements provide high accuracy but are slow, as tactile probes must be moved over large distances. Optical methods are much faster, yet their effective range is usually limited to a few meters, and they generally offer lower accuracy. Measurements of large-scale components are further complicated by varying environmental conditions (e.g., temperature gradients) and the accumulation of different error sources, making high-accuracy measurements difficult to achieve. These challenges motivated the authors to develop hybrid measurement systems (HMS) and methods for improving their accuracy. This paper describes the steps taken to build an HMS combining a large-volume, high-accuracy coordinate measuring machine with a structured-light scanner. It also presents a dedicated method for determining measurement uncertainty in HMS, based on a multiple-measurement strategy. A series of tests were performed on material standards with various shapes, dimensions, and geometric features, using both contact and optical systems. The measurement uncertainties were then evaluated using the developed method. Finally, the method was validated through tests conducted on a selected large-scale engineering object.

Coordinate measuring techniques are essential for determining the diameter and roundness of circular features, yet measurements based on short arc segments remain highly sensitive to form deviations, sampling strategy, and instrument error. With the increasing demands placed on metrology, the choice of suitable data calculation and analysis methods becomes crucial for reliable interpretation of results. This study presents a simulation-based analysis of diameter evaluation for an oval-shaped profile, considering different levels of form deviation, three orientations of the contour peak, and the presence of random measurement error. The analysis includes both complete contours and partial arc segments and evaluates four reference-circle-fitting methods (LSCI, MZCI, MICI, MCCI). The results show that shortening the measured arc increases the influence of local geometric irregularities and random error on the obtained diameter values. The fitting methods behave differently under these conditions: LSCI is strongly affected by the orientation of the deformation peak, while MICI and MCCI provide reliable results only for sufficiently long arcs. MZCI consistently delivers the most stable performance when only fragmentary data are available. These findings indicate that both the choice of reference method and the selection of an adequate arc length are crucial for ensuring reliable and meaningful diameter assessment.

This study discusses the development of training strategies for RRR (3 revolute joints) triaxial manipulators. Two robot structures and a control phantom were constructed using incremental technology. An universal algorithm was developed to process and autonomously repeat the trajectories of robot movements by imitation and learning. The coordinates of the model articulated positions were then saved as coordinates of the manipulator position. For validation purposes, the newly developed training strategies and the repeatability of robot movements were tested in stages. After the first stage of testing in terms of positioning accuracy, structural changes were introduced in the robot by mechanical engineering to improve its manipulation quality. Next, another training strategy for the improved robot version was developed for the same movement algorithm. This demonstrates the applicability of the developed control system in applications with different structures and requirement for high control-command quality (possibility of using the developed algorithm in various robot designs). Experimental results showed that the function of the developed RRR manipulator algorithm enabling the imitation of phantom trajectories and their learning and memorization, along with the consideration of individual training strategies, can be applied to differing structures, achieving positioning accuracy comparable to that of high-class motion equipment, and facilitating navigation of individual robot members. The system composed of the simplified physical model and the manipulator can directly simplify and globalize the control of the robot over significant distances. Additionally, the positioning accuracy was tested using the photogrammetric method, which is a complete novelty in robot positioning research. Furthermore, it was demonstrated that for the first construction of the robot, it is possible to achieve an accuracy of ±1 mm in the automatic replay mode. Moreover, a construction accuracy of ±0.52 mm at a maximum speed of 0.025 s/1° can also be accomplished after manual repeat of the different model movements, i.e., after a learning procedure.

This work aimed to assess the influence of the iQ Weight Control System on the weight, dimensional stability, and mechanical properties of injection-molded samples. The properties of products made from glass fiber-reinforced polyamide and 50% regrind from post-production waste were evaluated. The mechanical properties, such as impact strength and tensile strength, were measured to determine the material’s performance. Additionally, a spiral flow test was conducted to verify the process robustness and repeatability when producing with either virgin material or a blend of virgin and regrind material. The spiral flow test, which involves injecting the polymer melt into a spiral mold, provides insights into the processability and flow characteristics of the polymer under high shear rates. This test is crucial for assessing the consistency of the injection molding process and ensuring that the material maintains its properties across different production batches. Results demonstrated that, despite the viscosity reduction associated with regrind, the system successfully maintained a consistent shot weight, thereby stabilizing the amount of material injected into the mold cavity. The iQ Weight Control System activation led to an increase in impact strength from 9.50 kJ/m² to 10.78 kJ/m² for virgin samples and from 9.26 kJ/m² to 9.73 kJ/m for a 50/50 virgin/regrind blend.