# Experimental Investigation of Vertical Density Profile of Medium Density Fiberboard in Hot Press
###### Abstract  
This research investigates the performance of the boundary density fiberboard (MDF) with respect to hot press parameters. The performance of the board, type of glue, and production efficiency determine the optimum temperature and pressure for hot pressing. The actual temperature of the hot press inside the MDF board determines the properties of the final product. Hence, the optimal hot press parameters for the desired product are experimentally obtained. Moreover, MDF is experimentally investigated in terms of its vertical density profile, bending, and internal bonding under the various input parameters of temperature, pressure, cycle time, and moisture content during the manufacturing process. The experimental study is carried out by varying the temperature, pressure, cycle time, and moisture content in the ranges of 200-220 \({}^{\circ}\)C, 145-155 bar, 260-275 s, and 8-10%, respectively. Consequently, the optimum input parameters of a hot-pressing temperature of 220 \({}^{\circ}\)C, pressure of 155 bar, cycle time of 256 s, and moisture content of 8% are identified for the required internal bonding (0.64 N/mm\({}^{2}\)), bending (32 N/mm\({}^{2}\)), and increase in both the core and peak density of the vertical density profile as per the ASTM standard. medium density fiberboard; bending; internal bonding; vertical density profile; hot-pressing temperature; pressure; moisture content; cycle time +
Footnote †: journal: Medical Engineering, University of Bahrain, Isa Town P.O. Box 32038, Bahrain; [EMAIL_ADDRESS]  
Footnote †: journal: Medical Engineering, University of Bahrain, Isa Town P.  
in density at different positions in the fiber mat is of major concern because of the consequent variations in mechanical properties. Input temperature, pressure, cycle time, and moisture content in hot pressing determine the physical and mechanical properties of the manufactured MDF board [5]. A large number of boards (nearly 10-15%) or about one hundred thousand cubic meter per year are rejected in the market due to defects, such as weak internal fiber arrangement, low bending and internal bonding, sides looseness, delamination problems, and rough surfaces [6]. The major reason for these defects is the lack of appropriate understanding of the inter-relationship during the hotpress process among the initial process parameters, such as temperature, moisture content, platen pressure, and its impact on the properties of the board [7]. Consequently, the process optimization of MDF is important to overcome all of these issues. A viable solution is to develop a relationship between the hot press process parameters and its output results [8]. A number of researchers have examined the parameters of hot pressing during operation, while our study focusses on the parameters in the hot press only. In this research, the experiments are performed on 16 mm MDF board [9]. To perform the experiments, a long piece of 8 \(\times\) 4 feet MDF board is taken, and it is further divided into smaller pieces according to the requirements of lab tests. Furthermore, the vertical density profile (VDP) is a critical factor that determines the strength and quality of MDF panels [10]. The concept of the ratio of the modulus of bending of one layer to the sum of the modulus of bending of all layers in the previous time step, as previously given by [PERSON] and [PERSON] [11], is redefined according to the latest published findings. The equation given by [PERSON] et al. is used to calculate the modulus of elasticity of different layers of the fiber cake. This model gives an improved relationship between the peak and core densities at a low hot press platen temperature at 160 \({}^{\circ}\)C but with an increase in hot platen temperature to 198 \({}^{\circ}\)C, where the rise in peak density is comparatively high [12]. The results of laboratory studies indicate that the vertical density profile of MDF is made from a combination of processes that occur both during compaction and also after the press has reached its final position [13].