Evaluation of wood surface roughness by confocal microscopy

The main aim of this study is to define the usability of the confocal scanning optical microscope (CSOM) to evaluate the wood surface roughness. Therefore, systematic investigation was carried out to define the influences of CSOM on the acquisition of 2D surface roughness parameters. Mahr Perthometer was applied to get reference data to estimate the applicability of the CSOM. Because wood roughness parameters measured with stylus and optical methods are not always comparable a calibration method was conducted on a metal calibration etalon. After the calibration process, the roughness profiles taken with the optical and stylus units were much closer to each other and only the optical Rpk parameter was definitely higher due to artificial peaks generated by the optical system. In order to eliminate this measuring failure, the morphological filter option of the optical apparatus may be activated. The surface roughness parameters were measured on planed Scotch pine samples. The planed surface plains were produced with 0.2 mm parallel offset to investigate the structural influence of the single cutting plains. The obtained results show that the average values for Ra, Rq, Rz, Rk, and Rvk are close to each other for both measuring systems, only the optically measured Rpk values must be corrected. The standard deviations, however, are systematically slightly higher for optical system. This may be explained by the higher resolution of the optical system giving more fine profile details. The earlier developed and introduced dimensionless quantities, such as Abbott ratio, are also fully comparable for both systems provided that the optically measured Rpk values are also correct.

The effect of tool wear and planning parameters on birch wood surface roughness

In this study, the surface quality of birch wood (Betula) test pieces planned with experimental planning tools (ET1, ET2) and influence of tool wear of quality of surface were examined. These tools were made by surfacing using a submerged arc welding (SAW) technique and a mixture of alloying elements (cromium, tungsten, fero-manganese, silicon carbide) spread on the surface under industrial flux. Surface roughness was measured along and across wood fibre. According to the results of experiments it is obviously that average roughness parameters along fibre is lower than across. Planning tool wear results revealed that 3200 m of cutting length is not significant for tools ET1 and ET2 wear. The same can be said about tool nose width change: For ET1 from 2.8 to 2.9 μm, and for ET2 from 2 to 3.4 μm – effect of negligible changes of tool edge geometry on planned surface quality is low. Feed of planning tool played more significant role – twice higher feed per insert (ET1 – 1.00 mm, ET2 – 0.5 mm) showed lower surface quality after planning. To reach necessary wood surface quality, lower feed rate and suggested experimental planning tool ET2 with higher wear resistance than commercial tool is preferable for planning of birch wood.

Surface characteristics of scots pine wood heated at high temperatures after weathering

This study was conducted to investigate some surface properties of wood specimens of heat treated Scots pine (Pinus sylvestris L.) after weathering such as surface hardness, surface roughness, gloss, and color changes. Heat treatment of Scots pine wood was carried out by hot air in an oven for 1, 2, and 3 hours at 210, 220, and 230°C. The results showed that generally surface hardness losses of heat treated Scots pine wood were lower than that of un-heated Scots pine wood after weathering. Heat treated Scots pine wood gave smooth surface after weathering. Except for heat treatment at 230°C for 1 and 2 hours, heat treatment resulted in better glossiness compared to un-heated Scots pine wood after weathering. According to the test results, while heat treated Scots pine wood become lighter after weathering, un-heated wood become darken after weathering. In general, heat treated wood surface to become reddish and yellowish after weathering.

Weathering properties of Scots pine treated with some chemicals

This study was aimed to investigate the gloss, surface hardness, surface roughness, and color changes of Scots pine that was treated with some chemicals after six months of weathering exposure. Chromated copper boron (CCB), vacsol aqua, and imersol aqua were used as the impregnation chemicals. Scots pine wood specimens were impregnated with 3% aqueous solutions of the chemicals according to ASTM standards.The results showed that while chemical treatment caused a decrease in surface hardness, gloss, and lightness of wood specimens, it increased the surface roughness of the wood before weathering. While the gloss values of all treated Scots pine specimens increased after weathering, the gloss loss was observed for the untreated specimen after weathering. All of the treated and untreated Scots pine wood surfaces were softened after weathering. The chemical treatment caused a decrease of surface roughness of wood after weathering. While in terms of the gloss, surface hardness, and surface roughness changes, the vacsol aqua-treated pine specimens gave the best results. The CCB-treated Scots pine showed the best color stability after weathering.

Parameters optimization for ultrahigh-pressure pure water and abrasive water jet of Pterocarpus macarocarpus kurz processing

This work optimizes the parameters of ultrahigh-pressure water jet, with or without abrasives, for the cutting of Pterocarpus macarocarpus Kurz wood, a precious species. Parametric factors of cutting pressure, target distance and feed rate were analyzed with respect to the resultant surface roughness of the cuts on specimens using an orthogonal experiment. The optimal machining schemes were elected for water jets either with or without added abrasives based on microscopic evidences. The results showed that the impacts on the resultant surface-roughness of the factors with a given water jet, i.e. either with or without added abrasives, from the most to the least, are both in the order of water jet pressure>feed rate>target distance. Water jets with no added abrasives have lower cutting capacity, which was evidenced by the worse surface roughness of cuts resulted from rebound jet. Raising their kinetic energy, the probabilities of fracture from tearing would also rise, thus, inducing corrugation in the bottom with exacerbated overall surface roughness of cuts. Abrasive water jet has the feature of many ripples, decreasing the surface integrity of specimens. Therefore, to improve product quality of Pterocarpusma carocarpus Kurz wood, is to increase the portion that is smooth in the sections from water jet cuts by choosing carefully the process parameters. The investigation of water jet cutting in this work throws some light on the configuration of process parameters while applying ultra high-pressure water jets, both with and without added abrasives, to the cutting of wood products of precious species.

Measuring the surface roughness values of european hop-horn beam (Ostrya carpinifolia Scop.) wood

In this study, the samples obtained from European hop-horn beam (Ostrya carpinifolia Scop.) wood has been subject to cutting with circular saw, planing with a thickness machine and sanding with a caliber sanding machine (with no: 80 sand). After the specimens were processed in the machines in radial and tangential surfaces, their surface roughness values (Ra, Ry, Rz) have been determined in accordance with the ISO 4288 standard. According to the statistical results, the lowest roughness values have been achieved with the thickness machine. Similarly, the roughness values of tangentially cut surfaces have been found to be lower than the radially cut surfaces.

Optimization and analysis of processing parameters of wooden crafts based on ultra-high pressure water jet method

The investigation and application of computer-numeric-control (CNC)-based ultra-high pressure water jet technology used in the field of wood processing have been paid increasing attention. In order to further optimize the technique of processing parameters in wooden crafts processing, medium density fiberboard (MDF) and solid wood of Italian poplar (Populus euramericana cv.) were taken as he experimental materials. The orthogonal experiment method was applied and the influence of several processing parameters including sand regulating speed, air-dry density, water jet pressure, feeding speed and target distance was considered to analyze the surface roughness. The water jet experiments were conducted based on the patterns designed by AutoCAD software with aid of numerical control working system. By the measurement of surface roughness and calculations, the influence of each processing parameter was investigated and the optimal scheme was then proposed. This work could provide optimization of processing parameters to the manufacturing of wooden crafts including fancy wood floors, indoor decorative boards of timber structure and mahogany furniture et al., which has high application value and practical significance.

Evaluation of the effect of individual paramaters of oak wood machining and their impact on the values of waviness measured by a laser profilometer

This article deals with determining the effect of different degrees of thermal modification, different cutting speeds (20, 30, 40 m. s-1), different feed rates (4, 8, 11 m. min-1) and different rake angles (15, 20 and 25°) with a 1 mm layer of removed material, on the quality of the surface of the workpiece using the mean arithmetic variation of the waviness profile „Wa“. The release was secured by setting the ruler and firmly holding it in the desired position. The ruler so configured was all the time to milling all the setting options.The article evaluates the process of planar milling of natural and thermally modified oak wood (Quercus cerris). For the evaluation, the samples were thermally modified by the Thermowood process at a temperature range of 160-210°C. The quality of the treated surface was evaluated after the planar milling process. The results obtained from this research show that by increasing the cutting speed during the machining of thermally modified and natural oak wood, we achieve better values of the mean arithmetic deviation of the waviness profile. The values of the monitored characteristic can also be improved by lowering the feed rate and selecting an appropriate rake angle. Thermal modification always lowers the values of the monitored characteristic.

Performance of coated tungsten carbide in milling composite boards

The purpose of this research was to analyze the performance (wear resistance, surface roughness, chip formation, and noise level) of AlCrN, TiN, and TiAlN coated tungsten carbides in cutting composite boards. The composite boards of wood plastic composite, laminated veneer lumber, and oriented strand board were cut by the coated tungsten carbide tools in a computer numerical control router. The results show that the differences in structure among the composite boards resulted in the difference in clearance wear, chip formation, surface roughness, and noise level phenomenon. The abrasive materials in wood plastic composite generated the highest clearance wear on the coated carbide tools tested. TiAlN coated carbide tool provided better wear resistance, smoother composite boards surfaces, and lower noise levels.

The chips generated during up milling and down milling of pine wood by helical router-bits

Development of new helical edge router bits (helix angle 15°, 30°, 45°, and 60°) with a cutting circle diameter of 8 mm was studied. The purpose of the research work was to investigate chips formation and surface roughness characteristics in milling the pine wood by the straight and helical edge bits. The generated chips were classified in four types by sieving into spiral chip (5 mesh), flow chip (10 mesh), thin chip (30 mesh), and granule chip (< 30 mesh). The experimental results showed that the spiral chip was generated most often (on a weight percentage basis) by the bits during down milling process. More flow and thin chips were produced by the bits during up milling process. Better surface roughness was produced by bits during down milling compared to up milling. When the helix angle of the bits increased the amount of spiral and flow chips were increased and granule chip was reduced. The machined surface was better in roughness (lower Ra values) as the helix angle of the bits increased both in up milling and down milling processes.

A calibration method of the laser triangular measuring system to evaluate wood surface roughness

Due to the fact that wood roughness measurement results measured with stylus and optical methods are not always comparable a new calibration method was proposed. In order to compare the surface roughness parameters of the stylus tactile 2D roughness parameters and the optical 3D roughness parameters a systematic experiment has been carried out on fourteen wood species. The essence of this calibration method is the use of metal calibration etalons for Rz = 20 μm and Rz = 30 μm and the filter option of the optical measuring apparatus. After the calibration process, the roughness profiles taken with the optical and stylus units were much closer each to other decreasing the difference in the measurement results of the two systems. Our study prove that the laser triangular method is less usable for the planed wood surfaces.

Paper substrates for inkjet printing of uhf rfid antennas

Conventional papers are not suitable for printed electronics because they have a rougher surface than the plastic film commonly used for electronics printing. The paper surfaces were modified by coating and calendering processes to reduce surface roughness and electrical resistance of inkjet-printed UHF RFID antennas. The composition of coatings, the main component which included aluminum oxide pigment, had an influence on the surface roughness, the surface pore content and the electrical resistance of the inkjet-printed UHF RFID antennas on coated papers. Papers coated with a mixture containing 25% polyvinyl alcohol binder in combination with the cationic polymer PDADMAC without glyoxal crosslinker had the lowest surface roughnesses and the lowest electrical resistances of the inkjet-printed antennas. As the coating basis weight increased, the electrical resistance of the antennas increased. Reduction of the electrical resistance of the antennas was achieved after calendering coated paper. The design of the antennas had a significant effect on their electrical resistance, which increased with the length of the antenna.

Effects of natural weathering on surface characteristics of scots pine impregnated with wolmanit CX-8 and varnished

In this study, it was aimed to investigate the effects of weathering on some surface characteristics such as color and surface roughness changes of Scots pine impregnated with copper-containing chemical such as Wolmanit CX-8 (WCX-8) and varnished with synthetic varnish (SV), cellulosic varnish (CV), and polyurethane varnish (PV) were investigated. Results showed that while the WCX-8 impregnated and PV coated Scots pine specimens showed better color stability than other treatment groups after weathering, only CV coated Scots pine gave the most negative effect on color stability. While, the untreated (control) wood surface turned from red to green and yellow to blue respectively, after weathering, other all treatment groups gave reddish and yellowish tone after weathering. Weathering conditions increased the surface roughness of control (untreated) and other all treatment groups. The control group gave a rougher surface than other treatment groups after weathering. Surface roughness increases were the lower for CV coated Scots pine wood than other treatment groups. The results showed that while WCX-8 impregnation before varnishing gave better color characteristics, generally it caused to increase the surface roughness of Scots pine after weathering.

Evaluating of wetting-induced effects on the surface stability of sanded wood

A sanding is a common woodworking operation to smooth the surface prior to apply surface finish or coating materials. All cutting processes damage the upper layer of wood surface and sanding also creates a deformation zone. This deformation zone is sensitive to artificial or environmental actions, especially to wetting. In order to determine the effect of wetting on the surface properties, to get insight into the dynamics of surface movement as a function of time during the wetting, special 3D surface roughness measurements were carried out and evaluated. For sanding of samples the most common grit sizes were selected and P100 and P180 sand papers were used. Measuring the weight of the samples the dynamics of evaporation of the applied water was also determined. The surface modification after wetting is caused by moisture gradients in the upper layer associated with swelling and shrinkage resulting in permanent deformations. For this layer the most characteristic roughness parameters are the average roughness Sa and the Abbott parameters Spk, Sk and Svk. The extent of roughness variation due to wetting is characterised by the ratio of roughness after wetting to the initial roughness value. The measurement results have shown that the simultaneous infiltration and evaporation rate has a definite influence on the surface roughness modification. The most stable wood species with the least modification were the ring-porous species, following by the diffuse-porous and conifers species. The evaporation rate measured followed the same sequence for wood species investigated.

Impact of UV irradiance on selected parameters of Scots pine impregnated with some commonly used fire-retardants

This study was designed to determine some selected parameters such as gloss, surface roughness, and color changes of Scots pine wood impregnated with commonly used fireretardant (FR) chemicals after UV irradiance. Sodium acetate (SA), ammonium chlorite (AC), zinc chlorite (ZC), ammoniumsulphate (AS), and di ammonium phosphate (DAP) were used as fire retardants. Wood specimens were prepared from Scots pine (Pinus sylvestris L.). Before test, wood specimens were impregnated with 5 % aqueous solution of chemicals according to ASTM D 1413-76 standard. Results showed that UV irradiance caused gloss loss and increase surface roughness of FR impregnated and un-treated (control) Scots pine specimen. DAP was the most effective chemical in terms of reducing gloss loss and surface roughness of Scots pine after 750 h UV irradiance exposure. UV irradiance caused a dark, reddish, and yellowish color of impregnated and un-treated (control) Scots pine specimen after all UV irradiance periods. Total color changes in color (∆E*) exhibited a systematic trend to higher values with increasing UV irradiance time. Total color changes of ZC impregnated Scots pine were the lowest after 750 h UV irradiance exposure.

Some surface characteristics of varnished thermowood after weathering

This study was designed to investigate some surface characteristics such as glossiness and surface roughness changes of varnished thermowood after six months of weathering. Thermal modification of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) wood were carried out by hot air in an oven for 1, 2, and 3 hours at 205, 215, and 225°C. After the modification process, wood specimens were varnished using a polyurethane varnish (PV) and cellulosic varnish (CV). The natural weathering process caused an increase in the surface roughness of the test specimens according to the test results. The Scots pine and Oriental beech test specimens which were heat treated and varnished gave more favorable results compared to only varnish test specimens after natural weathering in terms of surface characteristics such as surface roughness and glossiness. Generally, as the heat treatment time and temperature increase, it is observed that the surface characteristics of the Scots pine and Oriental beech wood specimens improve positively. According to the results of the tests, the samples varnished with polyurethane varnish gave better results in terms of surface roughness at the end of the natural weathering process, whereas the samples varnished with cellulosic varnish gave better results in terms of glossiness values.