Some of the parameters influencing surface roughness of particleboard

Abstract

The objective of this study is to evaluate the effects of raw material type, pressure, shelling ratio and density on the surface characteristics of particleboard. The surface roughness was measured using contact stylus method. Mean peak-to-valley height (R_z) was used to evaluate surface characteristics of the specimens. Measurements were taken from both sides of the specimens along and across the sand marks. The results showed that raw material type, shelling ratio, density and pressure affected the surface roughness of particleboard, statistically ($p⩽0.01$). Increasing the shelling ratio, board density and pressure improved the surface roughness of particleboard, significantly. Boards consisting of a greater amount of pine particles had lower surface roughness values than those of panels consisting of more beech particles.

Introduction

Particleboard is a wood-based panel composite manufactured under pressure and temperature from particles of wood or other ligno-cellulosic materials and a binder. Decrease in raw material and the need to conserve natural resources initiated research regarding more efficient use of trees. Many particleboards can utilize low-grade logs such as thinning, bowed and twisted logs. They can also use wood waste material. All sawmills produce a lot of residues in the form of chips, sawdust and slabs. These residues can be used to manufacture some of the many kinds of particleboards. Wood as a building material has a number of disadvantages. Wood is a very variable material both between and within species, and not just in appearance but, more importantly, in density, strength and durability. Although the strength properties of particleboard are generally lower than natural lumber, it is more consistent. Other benefits of particleboard come from the fact that its properties can be engineered. Particleboard can be bought in much larger sizes than lumber [1], [2], [3], [4], [5], [6], [7].

Some of the typical applications for particleboard include floor underlayment, housing, cabinets, stair treads, shelving, table tops, furniture, vanities, speakers, lock blocks, sliding doors, interior signs, displays, pool tables, electronic game consoles and table tennis [8]. Interior fitment and furniture manufacturers are using increasing ratios of decorative surfacing materials for wood-based panels (particleboard and MDF). Both of these panels are manufactured as uniform, flat panels that provide excellent surfaces for the application of coating materials. These coated panels are used in the construction of cabinets, furniture, panelling, kitchen worktops and work surfaces in offices, educational establishments, laboratories, and other industrial product applications. The purposes of coating of particleboard surfaces with decorative overlays are to suppress the absorption of water and humidity, and eliminate the release of formaldehyde. The performance of the coated panels is dependent on the quality of the wood-based panel and the type of the coating material [9], [10], [11], [12].

Surface roughness of the particleboard is very important for coating with thin overlays such as melamine saturated papers, foils and thin films. Any surface irregularities on the substrate may show through the overlay films and papers influencing the quality of the final product. Surface roughness was investigated by several authors. Hiziroglu and Graham [13] determined that the particleboards made by using a 45-s press closing time with the same out-of-press thickness resulted in rougher surfaces than those made by using a 36-s press closing time. Boards with a 17.9 mm out-of-press thickness had also rougher surfaces in comparison to the boards with a 18.2 mm out-of-press thickness [13]. Neese et al. [14] stated that several factors affected mechanical processing and, in turn, affect surface roughness of the wood. These included tree growth rate, annual ring symmetry, and size and frequency of knots. A common property among these anatomical characteristics was that each represents a difference in material specific gravity [14]. According to Siemensky and Skarzynska; hardwoods have smoother surface than softwoods [15]. Hiziroglu and Suchsland reported that increasing moisture content of the particleboard caused high surface roughness values [16].

The objective of this study is to investigate the relationship between surface roughness of particleboard panels made in plant conditions and their manufacturing variables.