Abrasive water jet machining has become an indispensable process for cutting Kevlar fiber-reinforced polymers used in applications such as ballistics protection, race cars, and protective gloves. The complex and diffuse action of a large number of input parameters leads to the need to evaluate the quality characteristics of the technological transformation as a result of the deployment of experimental studies adapted to the specific processing conditions. Thus, the paper focuses on identifying the influence of different factors and modeling their action on the characteristics that define the quality of the cut parts, such as the kerf taper angle and the Ra roughness parameter, by applying statistical methods of design and analysis of experiments.

The 5000 series aluminum alloy 5083 is distinguished by excellent processability, excellent welding characteristics, and a strong resilience to corrosion, particularly in maritime environments. It is employed in the manufacture of ships, automobiles, spacecraft, and industrial buildings. The goal of the current study is to determine whether there is any relationship between the mechanical properties, structural characteristics, and cavitation erosion properties of aluminum alloy 5083 in the H111 state (rolled from 454 °C to 399 °C and annealed at 343 °C by holding in cooled air), followed by artificial ageing at (180 °C) with three maintenance periods of 1 h, 12 h, and 24 h, and at (140 °C) with three maintenance periods of 1 h, 12 h, and 24 h. The cavitation resistance experiments of the experimental samples were performed in accordance with ASTM G32-2016. The resistance to cavitation erosion was determined by making mean erosion penetration rate (MDER) or mean depth of erosion (MDE) analytical diagrams according to the duration of the cavitation attack and by measuring the maximum depth of cavitation erosion in the samples analyzed by stereomicroscopy and scanning electron microscopy. Finally, a structural correlation between the condition of the artificially aged laminate alloy and its resistance to cavitation erosion could be achieved: ageing at 180 °C, maintained for 24 h, could lead to a maximum depth of cavitation erosion MDE_max of about 5 µm.

Materiale Plastice - a peer-reviewed scientific journal,specialised in the field of chemistry, polymers, elastomers and plastics research

Abrasive waterjet cutting (AWJC) is widely used for processing Kevlar-reinforced polymer composites; however, surface quality is typically assessed using amplitude-based roughness parameters like Ra and Rz, which offer limited insight into the overall morphology of the machined surface. This study investigates the use of complementary roughness descriptors—focusing on profile height, distribution, spacing, and slope—to characterize the kerf wall morphology generated during the cutting process. Measurements were performed across different zones of the kerf wall under varied cutting conditions, enabling the examination of how specific process parameters influence these descriptors. All investigated parameters significantly influenced the four roughness descriptors, which proved to be strongly inter-correlated, reflecting a unified material removal mechanism. Furthermore, a clear distinction was highlighted between the smooth, uniform top zone and the rougher bottom zone featuring diagonal striations, confirming the sensitivity of these descriptors to local variations in cutting conditions.

The present paper aims to develop a systematic, prescriptive, and exclusively statistical problem-solving methodology that integrates scientific experimental design methods with the Six Sigma philosophy. This methodology was used for the study and continuous improvement of a direct dyeing process for textile materials. In the first stages of the methodology, the process was systematically analyzed; color difference was identified, using rank correlation as the main quality requirement of the customer; and the influence of the electrolyte concentration in the dye bath on this quality characteristic was tested, using analysis of variance. In the subsequent stages, a full factorial experiment was carried out to obtain a mathematical model describing the action of the main selected influence factors on the color difference; response surfaces and constant level curves were plotted to find the optimal settings of these influence factors. It was concluded that cotton fabric provides a more uniform chromatic reproduction, i.e., a lower color difference, compared to linen, and the electrolyte concentration of 20 g/L yielded the most stable chromatic performance for both fiber types.

The present paper aimed to develop a systematic, prescriptive and exclusively statistical problem-solving methodology that integrates scientific experimental design methods with the Six Sigma philosophy. This was used for the study and continuous improvement of a direct dyeing process for textile materials. In the first stages of the methodology, the process was systematically analyzed, the color difference was identified, using rank correlation, as the main quality requirement of the customer, and the influence of the electrolyte concentration in the dye bath on this quality characteristic was tested, using analysis of variance. In the subsequent stages, a full factorial experiment was carried out to obtain a mathematical model describing the action of the main selected influence factors on the color difference, and response surfaces and constant level curves were plotted to find the optimal settings of these influence factors. It was concluded that cotton fabric provides a more uniform chromatic reproduction, i.e. a lower color difference, compared to linen, and the electrolyte concentration of 20 g/L yielded the most stable chromatic performance for both fiber types.