Fakulta technologická

Statistical evaluation of metal plated polymer surfaces

Wed, 01 Jan 2025 00:00:00 GMT

Statistical evaluation of metal plated polymer surfaces Kubišová, Milena; Knedlová, Jana; Endlerová, Dagmar; Ludrovcová, Barbora The surface quality of metallized polymer parts plays a crucial role in the functional and aesthetic properties of the final product, especially in the automotive industry and consumer electronics. This study focuses on non-contact measurement of the surface structure of ABS polymer parts, metallized using vacuum technology with the application of copper, nickel and chromium layers. The measurement was performed on the Talysurf CLI 500 device and evaluated according to the current standards ČSN EN ISO 21920-1 and 21920-2, which define the profile roughness parameters and the methodology for their assessment. The measured data were subsequently analyzed using descriptive statistics and multivariate statistical methods including analysis of variance (ANOVA), which allowed to reveal differences between samples manufactured in different time periods and in different plating conditions. The results confirm that the metal coating significantly affects the values of key surface structure parameters (Ra, Rz), and indicate the need for consistent control of process stability. The study also confirms the benefits of statistical tools for quality assessment and supports their wider use in technological practice. © Published under licence by IOP Publishing Ltd.

Analysis of the laser beam trajectory and its impact on the cut in PMMA material

Wed, 01 Jan 2025 00:00:00 GMT

Analysis of the laser beam trajectory and its impact on the cut in PMMA material Knedlová, Jana; Bílek, Ondřej; Bartík, David Article investigates how laser toolpath interpolation (linear vs. circular) affects kerf width, dimensional accuracy, and kerf taper when CO2-cutting PMMA sheets (t = 3, 5 mm) on an ILS 3NM system (λ = 10.6 μm; P = 100 W). Lenses with f = 1.5″ and 2.5″ were assessed. At identical process settings adopted from prior work, linear toolpaths yielded larger outer dimensions and more pronounced kerf taper, whereas circular paths produced more stable kerf and smaller taper angles. In all cases, the top-surface kerf exceeded the bottom-surface kerf. Thinner sheets (3 mm) were more sensitive to focal length and heat accumulation. The results provide practical guidance for selecting optics and toolpaths to balance accuracy and edge quality in PMMA cutting and form an experimental basis for future AI-assisted process optimization. © Published under licence by IOP Publishing Ltd.

Comparison of the stiffnesses of three types of porous structures

Wed, 01 Jan 2025 00:00:00 GMT

Comparison of the stiffnesses of three types of porous structures Monková, Katarína; Monka, Peter Pavol; Božić, Željko; Rački, Iva The article deals with the investigation of the stiffness of selected porous structures. Three types of structures (Fisher-Koch S, Schoen IWP and Schoen F-RD) with cellular topology belonging to Triply Periodic Minimal Surfaces (TPMS) were modelled in PTC Creo software and additively manufactured by Direct Metal Laser Sintering (DMLS) technology. All samples were designed with a basic cell size of 10 x 10 x 10 mm at a specific mass of 0.5 g/cm3 to compare their properties. Based on the results, it was possible to see that the best bending stiffness was shown by the Schoen F-RD type structure.

Die lip buildup and polymer rotarance theory

Wed, 01 Jan 2025 00:00:00 GMT

Die lip buildup and polymer rotarance theory Kanso, Mona A.; Giacomin, Alan Jeffrey; Musil, Jan; Zatloukal, Martin Die drool is the unwanted accumulation of material spilling onto the open faces of an extrusion die. In this paper, we explore the intriguing roles of subtle batch to batch variations in nonlinear viscoelasticity and molecular structure on the dimensionless buildup. Specifically, we view the behaviors of high and low dimensionless buildup resin batches through the lens of sudden inception of steady shear flow, both measured and predicted by rigid bead-rod theory. We find that the high drool rate high-density polyethylene film resin exhibits higher shear stress upon sudden inception of steady shear flow than its low drool counterpart. We further find that both high-density polyethylene film resins, examined through the lens of rotarance theory, behave as suspensions of multi-bead rods (also called shish kebabs). Both high-density polyethylene film resins exhibit the same longest relaxation time, the same macromolecular moment ratios, and differ only in their Weissenberg numbers, and thus, in their amounts of nonlinear viscoelasticity.