Effect of Heat Treatment and Densification Temperature on Roughness, Hardness and Spring-back in Cylindrical Wood Densification

In this research, black pine (Pinus nigra Arnold) was shaped into cylindrical forms through a turning process and then underwent surface densification. The densification process was performed on a lathe using a spinning roller specifically designed and produced for this purpose. Heat-treated (3 hours at 160 °C) and untreated specimens (a large diameter of 33 mm and a small diameter of 21 mm) were used as test material. Two feed rates, low (0.05 mm/rev) and high (0.405 mm/rev), were used in the study. The lathe speed was kept constant at 800 rpm. During densification, the temperature of 600 °C was applied with a temperature blower. This was followed by rapid cooling in an environment of -18 °C. Surface roughness (Ra), hardness, and spring-back measurements were conducted on both densified and undensified areas of the cylindrical solid wood samples. After densification, the Ra value decreased for all specimens and densification conditions, and the radial and tangential hardness increased. The temperature applied during densification (600 °C hot air) did not have much effect on the spring-back in 33 mm diameter specimens, while the application of temperature in 21 mm diameter specimens reduced the spring-back. At low feed rates (0.05 mm/rev) in densification, lower spring-back was obtained.