Medium Density Fibreboard Panels Research Articles

A review on electrostatic powder coatings for the furniture industry

Although powder coatings have had a long history in metal-related industries, it is a relatively new technology for the furniture industry. However, its application on wood-based panels which are non-conductive and sensitive to high temperatures has rapidly increased with developments in low-temperature curing powder coatings and the production of special-grade MDF (medium density fibreboard) panels. Solvent based-paints are still the most used coatings in the furniture industry, followed by water based paints, and powder coatings. However, government legislation on the toxic chemicals used in solvents, particularly in relation to human health, has increased the consciousness of people which has forced furniture producers to use modern and environmentally friendly coating systems. There are many advantages of using powder coatings such as them being non-toxic, cost-effective, easy application, and durable to weathering. The powder coatings industry has recently developed low-temperature curing powders and process parameters for wood-based substrates, in particular for MDF. Regular MDF panels are not suitable for powder coating applications because the raw material characteristics, production processes, surface treatments, and storage conditions should be formulated according to powder-grade MDF requirements. MDF producers and furniture companies need to be informed about the details of the application process and key precautions. In this study, the powder coatings market, application processes, required characteristics of the MDF substrate, technological developments and recent studies are extensively given.

Transient response and failure of medium density fibreboard panels subjected to air-blast loading

This paper presents insights into the response and failure of medium density fibreboard (MDF) panels subjected to air-blast loading. The MDF panels are representative of a cheap, and potentially sustainable, structural material that is commonly used in homes and buildings. Simplified computational simulations were used to design a series of air-blast experiments to elucidate a range of responses and failures within the MDF. The blast-loaded MDF panels exhibited multiple surface cracks, substantial in-plane cracking throughout the less dense parts of the cross-section, and fragmentation failures. The transient results show MDF exhibits peak displacement that are many times greater than the permanent deformation, and that the internal damage due to cracking reduced the stiffness of the panels. These findings provide unique and detailed insights into the cracking and fragmentation of MDF that will prove valuable to blast protection engineers considering the effects of explosive detonations inside buildings containing MDF furnishings, and any increased risk of secondary blast injuries due to flying MDF debris. The experimental data can be used by modellers to validate simulations of damage due to explosive events in the future.

Medium-density fibreboard milling using selected technological parameters

The aim of this study was to investigate the effect of blade type and sharpness angle on blade wear, cutting power, and surface roughness. The study was conducted on medium-density fibreboard (MDF) panels. Two blade types were analyzed (high-speed steel and cemented carbides) along with three variants of sharpness angles (40°, 45°, and 55°). Machining operations were performed on a spindle moulder at a feed rate of 6.3 m/min and rotational speed of 4500 min-1. The blade wear criterion was adopted as the loss of cutter surface area measured on the rake face. Roughness was determined using the Ra parameter, which was measured at three points on the cross-section of the MDF panel. A new, multifaceted approach to the study of cutting a narrow surface of the MDF board was used, thanks to which the interaction of such parameters as blade wear, cutting power, and machining quality as well as the type of material of the knives and their angular parameters were determined. An increase in blade wear and cutting power was recorded with an increase in cutting path, while roughness at the MDF panel cross-section varied. The cemented carbides cutter with the 45° angle may be proposed as optimal, because it showed a relatively low wear and cutting power while providing good quality of the milled surface.

The Utilizing Rock Salt of Inorganic Filler in Medium Density Fibreboard (MDF) Production

Aim of study: To research the usage opportunities of the inorganic rock salt mineral in MDF production. Area of study: The materials were collected rock salt from Çankırı region, wood from the Western Black Sea region, respectively. The production was performed in a private company in Düzce. The tests were performed at Duzce Forest Faculty Laboratory and Gazi Woodworking Industrial Engineering Laboratory. Material and methods: In the Asplund Defibrator, chips were baked wtihin 7-7.5 bar vapor pressure and 180 ° C temperature for 4-5 minutes. According to the weight of dry fiber, 1.5% paraffin was given before fibrillation, fibrillation later was given 1% ammonium sulfate solution. Inorganic fillers prepared in a separate tank in order to use rock salt instead of lignocellulosic fibers in the production of 1 m³ MDF. After that urea-formaldehyde glue is prepared as three different solutions which include the rock salt respectively with 3% (20 kg), 6% (40 kg), 9% (60 kg). This press applies 185-190 °C temperature and 32-34 kg/cm² pressure to the mixture material in 270 second pressing time. MDF panels (2100x4900x18 mm) were produced in the process. Physical, mechanical and combustion tests experiments are performed over boards. Main results: MDF products which were added per cent 3 with the rock salt have more performance than the other MDF panels in this study. Highlights: The usage of the rock salt with per cent 3 is recommended in MDF products.

Effects of adding nano-wollastonite, date palm prunings and two types of resins on the physical and mechanical properties of medium-density fibreboard (MDF) made from wood fibres

L’étude porte sur les effets de l’ajout de nano-wollastonite (NW) et de résidus de palmier-dattier sur les propriétés physiques et mécaniques de panneaux de fibres à densité moyenne. Des résines d’urée-formaldéhyde (UF) et d’isocyanate (IC) ont été utilisées à 10 % et 5 %, respectivement, du poids sec du matériau pour produire les panneaux. NW à granulométrie < 100 nm a été utilisé à 5 et 10 % du poids sec des résines, mélangé et pulvérisé sur le matériau avant formation du tapis de fibres. Les résultats ont été ensuite comparés à ceux pour les panneaux sans NW. Ils indiquent clairement une moindre absorption d’humidité et un moindre gonflement en épaisseur pour les panneaux produits avec ajout de résine IC. L’ajout de résidus de palmier-dattier a augmenté significativement les valeurs IB des panneaux produits avec les deux résines, UF et IC. L’ajout de NW a réduit les propriétés mécaniques des panneaux produits avec la résine UF, et amélioré celles des panneaux produits avec la résine IC. En conclusion, les résidus de palmier-dattier peuvent être considérés comme matière première potentielle pour la production de panneaux de fibres à moyenne densité en utilisant les deux résines, UF et IC. D’autre part, l’ajout de NW est recommandé pour la production de panneaux composites avec 10 % de résidus de palmier pour compenser en partie leur moindre résistance mécanique.

Surface gloss of lacquered medium density fibreboard panels veneered with thermally compressed birch wood

Abstract Wood surfaces are typically sanded before the lacquer coatings technological processes. This article discusses the aesthetic properties of lacquer coatings formed on medium density fibreboard (MDF) panels, veneered with thermally compressed birch wood. The effect of thermal compression temperature, veneer side (loose vs. tight), the number of lacquer layers and spread rates on the gloss unit (GU) of lacquer coatings were determined. Rotary-cut birch veneer sheets were thermally compressed at various temperatures (150, 180 and 210 °C) and afterwards they were bonded to the surfaces of MDF panels. The lacquer was applied to the surface of veneered MDF panels in 1, 2 and 3 layers at the various spread rates, appropriate 50, 75 and 100 g/m 2 . The values of GU parameter were measured at three angles − 20, 60 and 85°. Statistical evaluation of GU parameter showed, that the number of layers, the amount of lacquer, the direction of wood fibers, the side of veneer and compression temperature significantly affect gloss of the surfaces of veneered MDF panels. Gloss increased with the number of layers and the amount of applied lacquer. Brightness decreases with the increase in temperature from 150 to 180 °C, while a further increase in temperature from 180 to 210 °C enhances GU. There is a significant difference between values of gloss (except for the 20° angle) measured along and across grain direction. The values of gloss measured along the wood fibers are higher than those measured across the grains. Thermal compression of veneer homogenises the surface and as a result the gloss of the loose and tight sides is uniform. Thermal compression of birch wood surface instead of its sanding before finishing improves aesthetic properties of wood, in particular surface gloss as well as reduces the required lacquer application rate. These findings make it possible to improve the technology of lacquer coatings of thermally compressed wood.

Improvement of indoor air quality by MDF panels containing walnut shells

High levels of Volatile Organic Compounds (VOCs) and extremes of Relative Humidity (RH) commonly reduce indoor air quality with associated negative effects on human health and wellbeing. Interior materials are known to be one of the main contributors to poor indoor air quality. Notwithstanding, they can also act as a sink for airborne pollutants and excess moisture through adsorption. In this paper, we evaluate the ability of Medium Density Fibreboard (MDF) modified with walnut shell to regulate RH, toluene, limonene, dodecane and formaldehyde. The physicochemical properties, including molecular size/shape, vapour pressure, polarity and boiling point of VOCs allowed them to represent a range of pollutants. Adsorption and desorption behaviour of MDF containing up to 15% walnut shell was evaluated in 2-L environmental chambers under dynamic conditions at 23 °C and 50% RH. The porous microstructure of the MDF and walnut shell and their chemical composition were analysed using SEM, XRD and FTIR. Compared to a control panel, walnut shell additions showed an improved ability to remove VOCs and formaldehyde from the indoor air and buffer humidity. Of particular significance was the irreversible sink effect of formaldehyde and dodecane. This was attributed to the porous surface of walnut shell increasing the specific surface area of the panel and thus its adsorption capacity. The improved capacity of buffer humidity also increased the ability to adsorb water soluble VOCs such as formaldehyde. This research provides for the first time significant evidence that walnut shell modified MDF can improve indoor air quality.

Failure analysis of a continuous press component in MDF production plant

Abstract This work presents the results of a failure analysis performed on a component of a continuous press that is a part of a process plant used to produce MDF (Medium Density Fibreboard) panels. This plant is composed of 2 counter rotating belts that are supported, internally, by small steel rollers, connected to each other by small axes. The failure occurred prematurely on rollers. These components undergo to static and dynamic stresses below the yield strength of material. Low alloyed steel is employed for the production of the rollers and the components are carburized on the external surface. The rollers present cracks on the external surface, that is in contact with the wood panels, already after few hours in service. Other components did not undergo cracking even for very long service times (about 5000 h). Both rollers that failed in service and rollers without cracks were characterized by optical and scanning electron microscopy in order to evaluate the microstructure of the components. In particular, the microstructure of the rollers was investigated on the surface and in the core of the rollers. Vickers micro-hardness measurements were employed for the characterization of the mechanical properties of the rollers. Successively, a cross section of a broken roller was characterized by scanning electron microscopy (SEM) On the same sample, after microstructural characterization, a micro-hardness profile was acquired from external surface to the core in order to evaluate possible over carburizing or oxidation phenomena. The results obtained from both the microstructural and mechanical characterization of the failed rollers indicate that the possible causes of the in service failure are related to quenching cracks or fatigue.

At-line validation of a process analytical technology approach for quality control of melamine-urea-formaldehyde resin in composite wood-panel production using near infrared spectroscopy.

The reactivity of melamine-urea-formaldehyde resins is of key importance in the manufacture of engineered wood products such as medium density fibreboard (MDF) and other wood composite products. Often the MDF manufacturing plant has little available information on the resin reactivity other than details of the resin specification at the time of batch manufacture, which often occurs off-site at a third-party resin plant. Often too, fresh resin on delivery at the MDF plant is mixed with variable volume of aged resin in storage tanks, thereby rendering any specification of the fresh resin batch obsolete. It is therefore highly desirable to develop a real-time, at-line or on-line, process analytical technology to monitor the quality of the resin prior to MDF panel manufacture. Near infrared (NIR) spectroscopy has been calibrated against standard quality methods and against 13C nuclear magnetic resonance (NMR) measures of molecular composition in order to provide at-line process analytical technology (PAT), to monitor the resin quality, particularly the formaldehyde content of the resin. At-line determination of formaldehyde content in the resin was made possible using a six-factor calibration with an R 2(cal) value of 0.973, and R 2(CV) value of 0.929 and a root-mean-square error of cross-validation of 0.01. This calibration was then used to generate control charts of formaldehyde content at regular four-hourly periods during MDF panel manufacture in a commercial MDF manufacturing plant.

Medium Density Fibreboard Made from Kenaf (Hibiscus cannabinus L.) Stem: Effect of Thermo-mechanical Refining and Resin Content

The present study deals with the physical and mechanical properties of dry-formed medium density fibreboard (MDF) made from renewable biomass kenaf (Hibiscus cannabinus L.) stem as a function of adhesive level and refining conditions. Raw material was prepared by heating for 5 min at pressure levels of 6 and 8 bars. Experimental samples with a target density of 700 kgm-3 were produced with 10, 12, or 14% urea formaldehyde as a binder. Physical properties of MDF panels, such as thickness swelling (TS) and water absorption (WA) as well as mechanical properties including modulus of rupture (MOR), modulus of elasticity (MOE), and internal bonding (IB), were evaluated. Based on the test results, resin content and refining pressure have significant effects on the physical and mechanical properties of MDF panels. High resin content and pressure produced MDF boards with low WA and TS but high MOR, MOE, and IB. At 8 bars pressure and 14% resin content, the MDF recorded optimum WA (83.12%), TS (20.2%), MOR (25.3 MPa), MOE (3450 MPa), and IB (0.51 MPa).

Effects of resin and moisture content on the properties of medium density fibreboards made from kenaf bast fibres

The effects of different factors including resin type, resin content and moisture content on the physicomechanical properties of medium density fibreboard (MDF) panels made from kenaf (Hibiscus cannabinus L.) bast fibres are investigated. The Taguchi method of experimental design is employed to determine the effects of the factors and to find the levels of factors that result in desirable properties. Three different commercial resins namely, urea formaldehyde (UF), phenol formaldehyde (PF) and melamine urea formaldehyde (MUF) are used in the manufacturing of kenaf MDF panels. The panels are produced with a target thickness of 9mm and density of 700kg/m3. The results indicate that resin type and moisture content have significant influence on the mechanical properties while resin content is the least significant. On the other hand, for physical properties resin content and moisture content have much lesser influence as compared to resin type. This initial study reveals that kenaf panels produced with MUF resin at higher resin loading and intermediate level of moisture content, show elevated properties in accordance with wood based MDF standard ANSI A208.2-2009 for Grades 130 and 155.

A simplified model on vertical density profile and shrinkage ratio of virgin and charred medium density fibreboard

ABSTRACTThis work is part of a wider scope of research on developing comprehensive pyrolysis model for medium density fibreboard (MDF) in fires. A simplified model is developed to predict the vertical density profile of virgin MDF. The model shows that vertical density profile can be reproduced using a second order conic curve. Several sets of experimental data are used to validate the model with promising results that are presented. Further investigation shows that the density difference between surface and core densities tends to maintain constant within a range of 300 to 450 kg/m3. Moreover, the model can predict the mean density with an error less than 30 kg/m3. Typical MDF panels were experimentally charred using thermogravimetric analysis and cone calorimetry to investigate the shrinkage and density of char. The actual char density is measured as 330 kg/m3 with a uniform density distribution along the char layer thickness. A model is developed to predict the shrinkage ratios. The restraining effect caused by surface deformation will lead to different vertical and horizontal shrinkage ratios. The volume reductions at vertical and horizontal directions are experimentally measured as 40% and 20% for the two tested MDF panels, which is comparable with the model predictions. Copyright © 2013 John Wiley & Sons, Ltd.

Modelling the Heat and Mass Transfer during Hot Pressing of Medium Density Fibreboard

Abstract This paper discusses the development of a one-dimensional mathematical model to describe the heat and mass transfer during the hot-compression of medium density fibreboard (MDF) composite panels. Five primary variables were considered during the model development: air content, water vapour content, bound water content, and temperature within the mat, and the extent of the cure of the adhesive system, characterized by the cure index. Different heat and mass transfer processes were identified for the transport of the heat and the moisture phases. The heat was transported by conduction and convection due to a temperature gradient, and the exothermic energy released by the curing of the urea formaldehyde resin, while the water phases were transported by bulk flow and diffusion due to total pressure and concentration gradients. The resulting differential-algebraic equation system was solved by the finite difference method. The mathematical model predicted temperature, moisture content, partial vapour pressures, and extent of adhesive cure within the mat structure under a typical hot-compression process. The model results allow a better understanding of the interacting mechanisms involved in a complex production process. The model can also assist to optimize the hot-pressing parameters for improved quality of MDF panel products, while reducing pressing time.

Determining thermal physical properties of pyrolyzing New Zealand medium density fibreboard (MDF)

For modelling the burning behaviour of New Zealand medium density fibreboard (MDF), thermal physical properties of both virgin and charred material have been experimentally investigated. An empirical equation is proposed to predict the vertical density profile along the MDF panel thickness. Then a simplified model is developed to determine the specific heat based on the experimental data obtained from differential scanning calorimetry (DSC). The measurements for thermal conductivity have been conducted using the transient plane source (TPS) method and the experimental results are compared to the literature values. Finally a set of one dimensional heat transfer experiments have been carried out to validate the proposed models. The comparison of different modelling schemes shows that a combination of the non-uniform vertical density model, the specific heat obtained using DSC and thermal conductivity model of Von Haas and Haselein gives the best predictions to the experimental results for the temperature range assessed.Compared to virgin MDF, the density distribution along the charred material is more even, leading to a 330kg/m3 local density which is comparable to the measured bulk densities of 305 and 303kg/m3. The overall volume reduction caused by shrinkage is measured as 40% vertically and 20% horizontally. Experimental investigations show that MDF char has similar thermal physical properties as softwood char. The specific heat of MDF char is measured to be 600–800J/kg/K from 40 to 110°C and the experimental measured thermal conductivity of MDF char is 0.09W/m/K.

On Determining Density and Specific Heat of New Zealand Medium Density Fibreboard

To model the burning behaviour of New Zealand medium density fibreboard (MDF), thermal physical properties of density and specific heat were experimentally investigated. An empirical equation is proposed to predict the vertical density profile along the MDF panel thickness. The model focuses on commercial MDF species with vertical density profiles that in general can be reproduced by a second order conic curve. The model predicted density profiles match the experimental data well and in general give better predictions to the core densities than to the peaks, which might partly because the hot pressing process has caused more complicated effects at the surface than at the core. The specific heat of MDF is measured experimentally using Differential Scanning Calorimetry (DSC). A simplified equation is developed based on the experimental outcome, which is found to be different from the models in the literature.

Properties of medium density fibreboard panels made from rubberwood and empty fruit bunches of oil palm biomass

This study presents an evaluation of the physical and mechanical properties of medium density fibreboards produced from mixture of rubberwood from RRIM 2020 clone and empty fruit bunch fibres. The evaluations are conducted to determine variance in density, moisture content, modulus of rupture, modulus of elasticity, internal bonding, thickness swelling and water adsorption for these mixtures. The significance level of p < 0.05 was used to determine the variations between different ratios of rubberwood and empty fruit bunch fibre blends effect on all properties studied. Most properties of medium density fibreboard panel made with 100% rubberwood fibres are significantly better than medium density fibreboard made with 100% empty fruit bunch fibres. Additional of 30% of empty fruit bunch in mixture had decreased modulus of elasticity by 148 MPa, modulus of rupture by 1.21 MPa and water adsorption by 0.05% compared to 100% rubberwood. Generally, among mixtures, panels containing less than 50% oil palm empty fruit bunch in the mixture exhibits better strength properties but lower physical properties. The dimensional stability (thickness swelling) of the panel made from the mixture of 70% rubberwood and 30% empty fruit bunch board displays the best performance among the mixture.

Characterisation of the bending stiffness components of MDF panels from full-field slope measurements

This paper deals with the characterisation of bending stiffness components of medium density fibreboard (MDF) by carrying out a single plate bending test. The approach couples full-field slope measurements with an inverse identification method. MDF panels manufactured with different fractions of Eucalyptus fibres and sugarcane bagasse particles were used. The slope maps generated across the plate surface were measured by the deflectometry technique. The curvature fields of the deformed plate were reconstructed by numerical differentiation afterwards. The virtual fields method was then implemented for material parameter identification under the framework of Kirchhoff–Love plate bending theory. The elastic properties obtained from the proposed data reduction (i.e. simultaneous identification of modulus of elasticity, Poisson’s ratio and shear modulus) were compared with values determined from classical three-point bending tests and reported in the literature. The set of properties were found in relatively good agreement.

Kenaf MDF panels: a statistical approach in parameter selection

The aim of this study was to determine the practicality of using conductive fillers in medium density fibreboard panels to enable uniform electrical conductivity in the panels to achieve uniform surface coating during powder coating. A relatively new concept of adding carbon black has been tried, triacetin has been used as a compatibliser to retain/improve the fibre–matrix interfacial bonding in the presence of the filler, and a soy based bioresin has been used as an alternative to conventional urea-formaldehyde resin system. As the properties of such composite systems depend on the proportion of their constituents, a statistical analysis based on Taguchi method has been used to study the complex multivariable system. A two-level, three-factor L8 orthogonal array was used to carry out a full factorial analysis to determine the effect each factor had on various panel properties. The key properties investigated in this report are: panel thickness, electrical conductivity, internal bond strength, modulus of rupture and modulus of elasticity. It was found that a mixture of 7% resin, 1% triacetin and 5% carbon black produced a panel with sufficient mechanical and conductive properties to be a viable alternative. The addition of carbon black showed up to 75% improvement in conductivity, with the Soyad adhesive system showing significant improvements in conductivity over the UF adhesive system itself.

Resin and wax distribution and mobility during medium density fibreboard manufacture

Fluorescently labelled UF resin and paraffin wax have been used at a medium density fibreboard (MDF) production facility to characterise resin and wax distribution and mobility on MDF fibre and panels. The major findings from these comprehensive mill-scale trials have been the mobility of UF resin on fibre throughout the MDF process, while wax mobility occurs only on panel pressing. Complex interactions exist between resin distribution and wood fibre wall penetration which collectively provide evidence for three-dimensional resin movement on fibre through the production process. Fibre exiting the blowline had relatively high rates of resin coverage with resin droplet sizes dominated by the process of resin smearing through fibre-fibre contacts. On passing through the dryer resin coverage of fibre reduces, before increasing again on panel pressing. Wax distribution on unpressed fibre was dependent on the mode of application with emulsion and slack wax addition at the refiner being relatively similar, but differing to emulsified wax added via the blowline. On pressing, wax distribution in panels was distinguished by wax type, and was independent of the addition points.

Investigating the CO 2 laser cutting parameters of MDF wood composite material

Laser cutting of medium density fibreboard (MDF) is a complicated process and the selection of the process parameters combinations is essential to get the highest quality cut section. This paper presents a means for selecting the process parameters for laser cutting of MDF based on the design of experiments (DOE) approach. A CO 2 laser was used to cut three thicknesses, 4, 6 and 9 mm, of MDF panels. The process factors investigated are: laser power, cutting speed, air pressure and focal point position. In this work, cutting quality was evaluated by measuring the upper kerf width, the lower kerf width, the ratio between the upper kerf width to the lower kerf width, the cut section roughness and the operating cost. The effect of each factor on the quality measures was determined. The optimal cutting combinations were presented in favours of high quality process output and in favours of low cutting cost.