Technical University in Zvolen OJS
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DEEP IMPREGNATION OF BINDER-FREE, LOW-DENSITY WOOD BOARDS WITH FLAME RETARDANTS
Get PDFThis study is aimed at making binder-free low-density wood boards from mechanically activated sawdust by the process of deep vacuum-pressure timber impregnation with aqueous solutions of flame retardants. The thermal decomposition of impregnated boards was examined by thermogravimetric analysis (TGA). Determination of the maximum flame retardant absorption was carried out by a factorial experiment. The SEM/EDX method was used to estimate the distribution of flame retardants across the entire thickness of the board. The fire-proof efficiency of flame retardants was determined as specified in the GOST 12.1.044-89 standards. It was found that the deep impregnation of binder-free boards with a density of 290 kg/m3 makes it possible to obtain a low-combustible material
PATTERNS OF CHANGES IN TECHNOLOGICAL ACCURACY OF PLANO-MILLING MACHINES DURING THE PERIOD OF THE CUTTING TOOL WEAR RESISTANCE
Get PDFPolynomial patterns of changes in the technological accuracy of the machine tool over the period of the cutting tool wear resistance were established. The software, which makes it possible to show regression models of the average value and the scattering field of the size of the manufactured parts depending on the degree of the tool wear, was developed. Based on the results of experimental studies of changes in the machining accuracy on six plano-milling machines during the wear resistance period of the cutting tool (ρ = 5 − 50 μm), regression models in the form of third-order polynomials were obtained. It was found that to ensure the machining accuracy within the tolerance (± 0.1 mm), the wear resistance period of the cutting tool should not exceed ρ = 30 μm, and the technical specification of the machine should correspond to an exceptionally high accuracy class.
CONVENTIONAL VS. INNOVATIVE METHODOLOGICAL COSTING PROCEDURE FOR THE PRODUCT MANUFACTURE FULFILLING THE PRINCIPLES OF THE CIRCULAR ECONOMY
Get PDFInnovative products, including wood plastic composite, point to the potential of using the principles of the circular economy. The increasing share of plastic waste combined with wood raw material creates great potential for meeting the environmental criteria of wood plastic composite products. The aim of the paper is to present a proposal for modifications of the standard methodological overhead cost calculation with the subsequent comparison of the results of the innovative methodological calculation, based on the investment plan for the production using recycled wood-plastic raw materials. The application of the Calculation of Machine Hours Rates requires precise identification of the production capacity in terms of machinery hours and composition of the calculation formula. Although the results of the comparison of price differentiation did not reveal a fundamental change in the cost allocation, it may differ for variations in other surface and volume product dimensions, changed wood-plastic component proportions or subsequent final surface treatment
OPTIMIZATION OF THE CNC MILLING PROCESS VIA MODIFYING SOME PARAMETERS OF THE CUTTING MODE WHEN PROCESSING MDF WORKPIECES
Get PDFThe modification in the surface quality of Medium Density Fiberboard (MDF) workpieces machined in a CNC milling machine is investigated in the paper. The quality of the milling process is affected by the surface roughness. The present work is focused on the influence of the following cutting parameters: rotation speed (n), feed rate (Vf) and radial depth of cut (h) in optimising the milling process and improving the quality of the milling surface. The roughness of the processed surfaces was measured with a roughness tester, type “Surftest SJ-210” (Mitutoyo, Japan). The surface quality is evaluated using the defined average arithmetical values of roughness parameters . The results of the current study showed the following optimal values of the variable factors that ensured the highest quality of the processed surface: rotation n = 18000 min-1, feed rate Vf = 3.5 m.min-1 and radial depth of cut h = 3 mm. Based on the experiments performed, graphical dependencies, presenting the influence of the individual factors on the quality of the processed surface were derived
THE EFFECT OF OUTDOOR WEATHERING OF THERMALLY MODIFIED SPRUCE AND PINE WOODS ON THEIR SURFACE PROPERTIES
Get PDFProducts from thermally modified wood used outdoors should be stable against sun, rain, wind, and biological agents. The effect of 1- to 24-month outdoor weathering of the Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) thermally modified woods “Thermo-D produced in Oy Lunawood Ltd Finland” (TWs) on their selected surface properties – colour, gloss, roughness, and mould resistance is analysed in the paper. With prolonged weathering, the surfaces of both Thermo-D wood samples lost their original yellow-red shadow. They continuously turned greyer – in the CIE L*a*b* colour system, they obtained greener and bluer colours, together with the logarithmic increase in the total colour difference ΔE*ab. Surfaces of both Thermo-D wood samples within the first four months of outdoor weathering turned much lighter with a higher gloss. However, they got darker and matter due to adsorbing soot and dirt. Similar changes, i.e., as in the lightness and gloss, occurred in the roughness of weathered Thermo-D woods, which firstly decreased and subsequently increased with further prolongation of weathering. Moulds Aspergillus niger and Penicillium brevicompactum, in all cases, intensively attacked spruce and pine wood – natural wood, Thermo-D wood, weathered natural wood, weathered Thermo-D wood
CHEMICAL CHARACTERISATION OF EUROPEAN BEECH (Fagus sylvatica L.) MATURE WOOD AND FALSE HEARTWOOD
Get PDFFalse heartwood in European beech (Fagus sylvatica L.) is a significant defect reducing the usability of the wood for aesthetic reasons. The aim of this work was to compare the chemical composition of mature wood and false heartwood of beech regarding their different coloring. The content of the main wood components, extractives, polyphenolic compounds, and soluble carbohydrates was determined. In addition, FTIR (Fourier transform infrared spectroscopy) analysis of mature wood, border zones and false heartwood was also performed. Chemical analyses showed a slightly higher content of holocellulose in false heartwood compared to mature wood. The differences in cellulose and lignin content are minimal. The content of both lipophilic and hydrophilic extractives is higher in mature wood. Hydrophilic extract from mature wood contains more phenolics and soluble carbohydrates compared to false heart. According to ATR-FTIR (Attenuated total reflectance Fourier transform infrared spectroscopy) analysis it can be assumed that there is an increase in the content of polyphenolic extractives in the border zone, especially in the darkest colored zone next to the false heart
SPECIFICS OF AEROBATICS TERMINOLOGY
Get PDFThe present paper deals with the specifics of terminology of both powered and glider aerobatics. In addition to English terminology and Slovak and Czech equivalents, the paper presents also selected aspects of professional jargon and typical phraseology applied in international aerobatic contests from the perspective of judges. Although the Slovak-English terminology equivalents in terms of flight aerodynamics and mechanics are tackled in the work Slovenský letecký slovník, terminologický a výkladový by Nedelka a kol. (1998), it is possible to identify certain elements of the terminology, which are not discussed in the mentioned work. The aim of the paper is to expand on the terminology listed in the aforementioned dictionary and define terms commonly used in aerobatic practice. Moreover, the additional expressions are briefly analysed and compared in terms of word formation
MEASUREMENT OF THE ROUGHNESS OF THE SANDED SURFACE OF BEECH WOOD WITH THE PROFILE MEASUREMENT SOFTWARE OF THE KEYENCE VHX-7000 MICROSCOPE
Get PDFSanding is the most important way of reducing unevenness and preparing the surface for the final treatment. To optimize sanding, it is necessary to quantify the effect of abrasive grit size on surface roughness. The paper deals with the methodology of measuring the surface roughness parameter Ra of beech wood (Fagus sylvatica L.) using a Keyence VHX-7000 digital microscope. After milling, the samples were sanded with abrasives with grit size from P40 to P150, using an eccentric sander. Roughness was evaluated in two directions according to ISO 21920 (2022) standards. Using a two-factor analysis of variance the positive effect of grit size on roughness was proven. It improved on average by 38% in the direction perpendicular to the grain and by 20% parallel to the grain. The theoretical knowledge about equalizing the unevenness of the surface by sanding and reducing the difference between the roughness in two directions is proven in the paper.
CHANGE IN THE COLOUR OF TRANSPARENT SURFACE FINISH ON HYDROTHERMALLY TREATED WOOD
Get PDFThe paper deals with the influence of ageing in the dark and in the light on the colour of a transparent surface finish. In the experiments, Paper birch (Betula papyrifera Marsh) and Norway maple wood (Acer pseudoplatanus L.) were hydrothermally treated at 135 °C under saturated water vapour for 6 hours. The colour parameters were measured after native wood and thermally treated wood were surface finished. Three different types of surface finishes (acrylic-polyurethane, polyacrylic and aldehyde resin, and alkyd resin) were applied on the wood surfaces. The colour parameters of the tested surfaces (system CIE L*a*b*, chroma C*, hue angle h°) were measured immediately after surface finishing and ageing. The tested samples were aged either in the dark or in the sunlight behind windows glass, in the interior, for 60 days. The results showed that the colour of the wood and the colour of surface finishes changed after ageing in the dark and the light. The changes were different. The surfaces mostly lighten up in the dark and darken in the light
COMPARISON OF THE ATTRIBUTES OF THE WOOD PROCESSING INDUSTRY AND AUTOMOTIVE AND ENGINEERING INDUSTRIES IN THE CONTEXT OF QUALITY MANAGEMENT SYSTEMS
Get PDFThe aim of the paper is to compare the effect of implementing a more extensive scope of methods and quality management approaches of the enterprises in wood processing, automotive and engineering industries in Slovakia. The automotive and engineering industries have been selected for comparison because there is a significant difference in the approach of the state support and incentives of these industries as well as they are important manufacturing industries with a significant GDP share and export rate in Slovakia. At the same time, there is a presumption of several common determinants of implementing quality management systems and the circular economy potential in comparison with the wood-processing industry. The results of performed analyses revealed the existence of significant relations among capital structure and the complexity of using the quality management methods, tools and approaches