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Barrel tools are increasingly used in high-precision machining of free-form surfaces. However, limited studies evaluate their performance specifically on spherical geometries, where tool–surface contact characteristics differ significantly. Understanding how tool geometry and process parameters influence surface quality and cutting forces in such cases remains underexplored. This study evaluates how barrel cutter radius and varying machining parameters affect cutting forces and surface roughness when milling internal and external spherical surfaces. Machining tests were conducted on structural steel 1.1191 using two barrel cutters with different curvature radii (85 mm and 250 mm) on a 5-axis CNC machine. Feed per tooth and radial depth of cut were systematically varied. Cutting forces were measured using a dynamometer, and surface roughness was assessed using the Rz parameter, which is more sensitive to peak deviations than Ra. Novelty lies in isolating spherical surface shapes (internal vs. external) under identical path trajectories and systematically correlating tool geometry to force and surface metrics. The larger curvature tool (250 mm) consistently generated up to twice the cutting force of the smaller radius tool under equivalent conditions. External surfaces showed higher Rz values than internal ones due to less favorable contact geometry. Radial depth of the cut had a linear influence on force magnitude, while feed rate had a limited effect except at higher depths. Smaller-radius barrel tools and internal geometries are preferable for minimizing cutting forces and achieving better surface quality when machining spherical components. The aim of this paper is to determine the actual force load and surface quality when using specific cutting conditions for internal and external spherical machined surfaces.

This study describes the effect of electron radiation on the macro- and micro-mechanical and tribological properties of composite polypropylene filled with 25% glass fiber. Micro-mechanical and tribological properties were investigated both on the sample surface and at various depths below the surface. Polypropylene was irradiated with radiation doses of 15, 33, 45, 66 and 99 kGy. As the results show, electron radiation has an influence on the change in PP’s structure, in which due to the electron radiation, a crosslinked phase and an increase in crystallinity are formed. These changes in morphology are reflected in an enhancement of micro-mechanical and tribological properties both at the surface and in deeper layers below the surface. More crosslinking and recrystallization occur across the sample’s cross-section up to a depth of 2 mm, where greater micro-mechanical and tribological properties are also measured. The difference between the surface and the center of the material can be up to 32%. The optimum radiation dose appears to be 45 kGy, where the maximum crosslinking, highest crystallinity and best micro-mechanical and tribological properties are found. The difference between non-irradiated and irradiated filled PP is 52% in indentation hardness. In terms of macro-mechanical properties, the tensile modulus increased by 44% (45 kGy). This translates into higher surface wear resistance and the overall stiffness of the part. Higher doses of radiation cause the beginning of degradation processes, which are manifested by a decrease in the degree of embedding, crystallinity and thus micro-mechanical and tribological properties.

This publication deals with the study of the mechanical properties of injection-molded polypropylene parts depending on the process parameters and the distance from the gate location in which the mechanical properties were investigated. Due to the fact that the mechanical properties of injection-molded parts are not the same at all locations, this research was designed to investigate the inhomogeneity of the properties of injection-molded parts along the length of the product. The inhomogeneity is affected by various influences, including distance from the sprue mouth, melt and mold temperature, injection pressure, crystal structure, and others. It was demonstrated that mechanical properties are not uniform over the entire injected product. Contrary to popular belief, mechanical properties can vary along the flow length due to uneven cooling and process parameters. Injection pressure and mold temperature significantly affect the mechanical properties of the injection-molded parts. The limiting injection pressure is 40 MPa and the mold temperature is 40 °C. The difference in individual spots in an injected article was up to 37%. Changes in mechanical properties are closely related to changes in morphology (crystallinity measured by DSC) caused by different injection molding process parameters. As is evident from the aforementioned results, the possible benefits of this work for injection molding of polymer products are apparent. Suitably chosen gate location, surface of the cavity, and process parameters can ensure targeted improvement of mechanical properties in stressed parts of a product.

Today, more and more importance is given to the improvement of polymer materials’ wear resistance, i.e., their micro-mechanical and tribological properties, which could widen their application in practice. The properties of materials can be modified by several methods, among them exposure to electron radiation. This study focuses on the effect of varying radiation intensity (15 kGy to 99 kGy), depth of penetration, and subsequent structure modification of injection-molded polypropylene on tribological and micro-mechanical properties. Electron radiation influences the structure of individual layers, thus improving or degrading their properties. Hence, the depth of penetration can be examined by instrumented hardness tests and scratch tests. Due to irradiation, surface properties and wear resistance increased by up to 105% (from 38 MPa to 78 MPa). As the results show, an increase in mechanical properties was recorded in the direction towards the center of the sample (from 72 MPa to 82 MPa). Micro-mechanical tests were also confirmed by the observation of cross-linking changes (gel test) as well as crystallinity increases (wide-angle X-ray diffraction and microtome cuts). This finding could have a significant effect on the manufacturing and subsequent modification of injection-molded polypropylene parts, which opens new possibilities in practice for this material. The increased surface wear resistance enables the use of parts for which the durability and abrasion resistance of the surface are demanded, especially in applications facing exposure to long-term cyclical loads (e.g., gears).

This study describes the influence of polymer flow length on mechanical properties of tested polymer, specifically polycarbonate. The flow length was examined in a spiral shaped mould. The mould cavity’s surface was machined by several methods, which led to differing roughness of the surface. The cavity was finished by milling, grinding and polishing. In order to thoroughly understand the influence of the mould surface quality on the flow length, varying processing parameters, specifically the pressure, were used. The polymer part was divided into several segments, in which the micro-mechanical properties, such as hardness and indentation modulus were measured. The results of this study provide interesting data concerning the flow length, which was up to 3% longer for rougher surfaces, but shorter in cavities with polished surface. These results are in disagreement with the commonly practiced theory, which states that better surface quality leads to greater flow length. Furthermore, evaluation of the micro-mechanical properties measured along the flow path demonstrated significant variance in researched properties, which increased by 35% (indentation hardness) and 86% by indentation modulus) in latter segments of the spiral in comparison with the gate.

This research investigates the micro-mechanical and tribological properties of injection-molded parts made from polypropylene. The tribological properties of polymers are a very interesting area of research. Understanding tribological processes is very crucial. Considering that the mechanical and tribological properties of injected parts are not uniform at various points of the part, this research was conducted to explain the non-homogeneity of properties along the flow path. Non-homogeneity can be influenced by numerous factors, including distance from the gate, mold and melt temperature, injection pressure, crystalline structure, cooling rate, the surface of the mold, and others. The key factor from the micro-mechanical and tribological properties point of view is the polymer morphology (degree of crystallinity and size of the skin and core layers). The morphology is influenced by polymer flow and the injection molding process conditions. Gained results indicate that the indentation method was sufficiently sensitive to capture the changes in polypropylene morphology, which is a key parameter for the resulting micro-mechanical and tribological properties of the part. It was proven that the mechanical and tribological properties are not equal in varying regions of the part. Due to cooling and process parameters, the difference in the indentation modulus in individual measurement points was up to 55%, and the tribological properties, in particular the friction coefficient, showed a difference of up to 20%. The aforementioned results indicate the impact this finding signifies for injection molding technology in technical practice. Tribological properties are a key property of the part surface and, together with micro-mechanical properties, characterize the resistance of the surface to mechanical failure of the plastic part when used in engineering applications. A suitable choice of gate location, finishing method of the cavity surface, and process parameters can ensure the improvement of mechanical and tribological properties in stressed regions of the part. This will increase the stiffness and wear resistance of the surface.

This work is concerned with forming, specifically deep drawing, and its influence on the micro-mechanical properties of sheet metal. In practice, there are several applications in which fractions can occur due to weak spots in the deep-drawn sheet metal, especially after long-term use. The deep drawing process was carried out on BUP–600 machines using the LHD (Limiting Dome Height) method, which uses a forming tool with a diameter of 100 mm and bead groove. Sheet metals X8CrMnNi19-6-3 (1.4376) with thicknesses of 1, 1.5, and 3 mm were selected for this process. To study the effect of a lubricant on the formability of the sheet metal, deep drawing without and with a lubricant was compared. An FEM analysis was conducted to identify critical points in the deep drawing process, and the results were later compared with real results. The analysis was conducted using the AutoForm program. The micro-mechanical properties of these points were subsequently examined. The specified points on the formed part showed significant differences in their micro-mechanical properties, suggesting a higher strength but also less resistance to fractures. The difference in micro-mechanical properties (indentation and Vickers hardness) in points that were not deep-drawn and points located in critical areas was up to 86%. Significant changes in behavior were found in the indentation modulus and plastic/elastic deformation work as well. This study demonstrates the significant effect of the use of a lubricant in achieving the deep drawing of the sheet metal. The application of a lubricant resulted in a 33% increase in drawing range compared to drawing without lubrication. This study has a significant influence on the deep drawing of sheet metals in practice, showing the fundamental influence of the lubricant on the drawing process and also showing the problem of critical points that need to be eliminated.

This study investigated the mechanical, thermal, and morphological properties of acrylonitrile butadiene styrene (ABS)-based nanocomposites reinforced with different types and concentrations of nanofillers. The uniaxial tensile testing results indicated that Young’s modulus (E) generally decreased with increasing filler content, except at 0.500 w.% filler concentration, where a slight increase in stiffness was observed. A statistically significant interaction between sample type and filler concentration was identified (p = 0.045). Fracture toughness measurements revealed a significant reduction in impact resistance at 1.000 w.% filler concentration, with values dropping by up to 67% compared with neat acrylonitrile butadiene styrene. Dynamic mechanical vibration testing confirmed a decrease in stiffness, as evidenced by a shift of the first resonance frequency (fR1) to lower values. Hardness measurements including indentation and Shore D hardness exhibited an increasing trend with rising filler concentration, with statistically significant differences observed at specific concentration levels (p < 0.05). Scanning electron microscopy analysis showed that nanofillers were well dispersed at lower concentrations, but agglomeration began above 0.500 w.%, resulting in void formation and a noticeable decline in mechanical properties. The results suggest that an optimal filler concentration range of 0.250–0.500 w.% offers an ideal balance between enhanced mechanical properties and material integrity.

This article examines the effect of the number of inserts in a milling head on cutting forces during machining and the resulting surface roughness. An experimental study was used to compare results using different insert configurations while maintaining a constant feed per tooth. The resulting cutting forces and surface roughness were analyzed and discussed in the context of the optimal setting of cutting conditions. It was found that a reduced number of inserts does not necessarily lead to a reduction in cutting forces during machining and that while maintaining the feed per tooth with a reduced number of inserts, the roughness is not significantly affected. An unexpected result was that inserts can differ in terms of the surface quality achieved. This research also shows that individual inserts can vary substantially in the force load they generate, a phenomenon that can be attributed to their dimensional differences. This study provides valuable insights for industrial applications that require precision machining concerning cutting forces and surface quality. It can potentially improve the efficiency and quality of machining in industrial applications.

This article deals with the use of Ultra-nano indentation Tester UNHT 3 for the measurement of (ultra nano) mechanical properties. The effect of electron beam (EB) radiation on Polybutylene terephthalate (PBT) was investigated. To clarify whether crosslinking could take place without or only with the presence of a crosslinking agent, special attention was paid to the incorporation of this agent into tested polymer. In this study we have investigated the effect of crosslinking agent, and instantaneously electron beam radiation-induced crosslinking in the presence of Triallyl cyanurate on various mechanical properties of PBT. The results show that the influence of radiation has improved the observed properties in the surface layer. The increase in ultra-nano properties was around 26% over the basic material. Engineering plastics like Poly (butylene terephthalate) due to their desirable properties have various industrial applications.