Materials Karakteristik Retak Kupas And Kekasaran Permukaan Finir Kayu Cepat Tumbuh Dan Pengaruhnya Terhadap Laminated Veneer Lumber

26 Quality Improvement Division of Forest Product Department of Faculty of Forestry, Bogor Agricultural University, Indonesia 3.3.1 Peeling process 3.3.1.1 Sengon and jabon logs preparation for rotary cutting Tree rings have been used for a long time in areas outside the tropics to characterize the presence of juvenile and mature wood. Considering distinct growth rings are absence in sengon and jabon trees, segmented ring was considered to be practically useful for characterizing their juvenility. A specified 1 cm width of segmented rings was made from pith to bark on the cross section of logs and numbered consecutively No. 1-7 as shown in Figure 10. Four logs section bolts in diameter of 28 cm for sengon and jabon in length of 60 cm were selected. The first two bolts were soaked in water at room temperature called unboiled, and the other two bolts were subjected to boiling process in hot water at 75°C for 4 h called boiled. Subsequently, the bolts were peeled off to obtain veneers in the thickness of 3mm. For each peeling, a sharp knife was used. The other factors such as knife angle, peeling angle, log temperature, peeling speed were kept constant in the study. The knife angle was 20°, and peeling angle was 21°. The veneers were peeled using a spindle less rotary lathe. The bolts were peeled up to core diameter of 6 to 8 cm in order to produce veneers from the 7 different segmented rings Figure 10. The veneers were collected and grouped for each segmented rings and numbered consecutively from near the pith number 1 to near the bark number 7. Veneer in each segmented rings was measured for characterizing the thickness variation, lathe checks, surface roughness and contact angle.

3.3.1.2 Poplar logs preparation for rotary cutting

Logs were peeled by using “SEM Automation S500” at LaBoMaP Laboratoire Bourguignon des Matériaux et des Procédés, Ecole National Superieure d’Arts et Matiers ENSAM Cluny, Bourgogne, France. It could peel logs from 450 to 850 mm in length and 180 to 500 mm in diameter. Logs were peeled by using a 1° clearance angle, 1 ms -1 speed and with a moderate pressure rate of 10 to limit lathe check growth and thickness variation Lutz 1974; Feihl 1986; Marchal et al. 2009. Before peeling, each log was holed by 1 cm diameter drill bit from bark to pith, to mark the radial segment of veneers sample. Each cultivar of poplar logs were peeled with 3 mm thickness. The logs were peeled until the core diameter of 14 cm. According to transition age resulted from fiber length trait see Chapter 2, we divided poplar veneers into two types. First, veneers from mature wood taken from bark to 16 th segmented rings. Second, veneers from juvenile wood taken from 15 th segmented rings to core diameter. Veneers were dried with a vacuum dryer to ensure a flat veneer surface dried until they reached 8 - 10 moisture content. In each radial segment veneer samples in the size of 10x60 cm were kept in plastic for analyzing veneer qualities.