45 Sengon and jabon log sections bolts in length of 60 cm were taken from
each tree. Four bolts of about 28 cm in diameter 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, nose bar pressure, 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. LVL with the dimension of 20mm x 20mm x 500mm
from each segmented rings was produced.
4.4.2 LVL production, glue bond and bending strength tests 4.4.2.1 LVL production
The veneer specimens were conditioned at relative humidity RH of 85 and temperature of 25°C to an air-dry moisture content of 12. LVL panels with
dimension of 20x20x500 mm were manufactured by 3 mm veneer thick 7-ply at each segmented rings. Veneers were selected randomly in each segmented rings.
LVLs of 7 layers of 3 mm veneer were made, so that the target LVL thickness of 20 mm was achieved.
There were two different lay out that were used in this study. First lay out, LVL with loose side veneers glued with theirs tight side called type I. Second lay
out, LVL with loose side veneer glued with its loose side called type II see Figure 23
a b
Figure 23 Type I layout: loose-tight side lay out a and type II layout: loose-loose side lay out b
1
3 2
4 5
6 7
1
3 2
4 5
6 7
veneer adhesive
lathe check
46
4.4.2.2 Gluing process
PVAc Poly Vinyl Acetate was used as the adhesive. The vinyl adhesive used was marketed under the name INWOOD P 900 A
®
. It is in the form of an emulsion and ready for application. The PVAC resin had a viscosity of 90-110
poise at 23°C, pH 4-5, solid material 50+1 and a density of 1.23 gcm
-3
. Table 8 summarizes the conditions of the gluing process.
Tabel 8 Condition of gluing process of sengon and jabon laminated veneer
lumber made of 3 mm veneers Gluing parameters
LVL from 3mm veneer Veneer moisture content
11 – 13
Room temperature during gluing process 25 - 27°C
Average adhesive spreading rate gm
-2
260 Application instrument
Hand brushing Open assembly time
8 minutes Cold press pressure
2.5 kgcm
-2
Cold press pressure time 45 minutes
4.4.2.3 Glue-bond and bending strength test
Tests for the glue bond and bending strength properties were conducted on test specimens prepared from the LVL panels. Prior to the testing, the specimens
were conditioned for 2 weeks at 25 °C and 85 relative humidity RH to air dry moisture content around 12. Total samples tested were 122 Samples. The glue
bond and bending tests were carried out on an INSTRON universal testing machine. Perpendicular to the fiber and glue line flatwise and four point bending
test for modulus of rupture MOR and modulus of elasticity MOE tests were carried out according to EN standard EN 789. Specimen size for the bending
tests was 400 mm long by 20 mm wide by 20 mm thick of LVL. Glue-bond tests were also carried out according to JAS SE 11 and modification of SNI 01-5008.2-
2000. The dimension of test samples was 100 mm length by 20 mm width by 20 mm thick. A loading rate of 10 mm min
-1
was used in all tests according to the JAS SE 11. Loading on the glue bond test was continued until separation between
the surfaces of the specimens occurred.
4.5 Method for production of poplar cultivars and douglas-fir LVL
The peeling process and LVL production of poplar cultivars and douglas-fir were performed in LaBoMaP Laboratoire Bourguignon des Matériaux et des
Procédés, Ecole National Superieure d’Arts et Matiers ENSAM Cluny,
Bourgogne, France and Laboratory INRA- Centre de Nancy, France.
4.5.1 Poplar cultivars and douglas-fir 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
