Effect of thermal modification on properties and milling behaviour of African padauk (Pterocarpus soyauxii Taub.) wood

Abstract

The purpose of this study was to analyze the effect of thermal treatment on chemical changes, mechanical properties and machining behavior of African padauk wood. Thermal modification of padauk wood was carried out at 3 different temperatures (160 °C, 180 °C, and 210 °C). Effect of modification temperature on chemical constituents and bending properties of padauk wood were ascertained. Thermally modified and un-modified samples were subjected to milling operation with combination of various processing parameters such as cutting speed (20, 30, 40 m/s), feed speed (4, 8, 11 m/min) and rake angle (15°, 20°, 25°), to obtain the optimum combination in terms superior surface quality (surface roughness and surface waviness) and minimum energy consumption. Cellulose and lignin proportion increased while hemicellulose proportion reduced significantly following thermal modification. Modification temperature, particularly 210 °C, had significant effect on the chemical constituents and bending strength of padauk wood. Modification up to 180 °C did not cause any significant loss in bending strength and bending stiffness, but the strength and stiffness loss was significant when samples were modified at 210 °C. Best surface quality with minimum energy consumption was obtained in African padauk wood thermally modified at 210 °C and milled with a cutting speed of 20 m/s, rake angle of 20° and feed rate of 4 m/min.

Keywords

• African padauk
• Thermal modification
• Strength
• Stiffness
• Milling
• Surface quality