The manufacturing process of Duobalken® und Triobalken® corresponds to that of glulam, whereby larger individual cross-sections are glued together.
Boards or scantlings with a thickness up to 80 mm (with a width up to 280 mm) or up to 120 mm (with a width up to 100 mm) are first dried to a moisture-content of approximately 15%, then planed. The dried boards or scantlings are strength-graded visually. The individual boards or scantlings are jointed together lengthwise to a theoretically infinite lamella using fingerjoints (glued connection between the edges of two boards which have a shape similar to a hand).
The lamellas are planed, and adhesive is applied over the entire broad sides of the lamellas. Two (Duobalken®) or three lamellas (Triobalken®) are stacked on each other and glued together under pressure bed. The resulting cross-section then hardens under pressure. After hardening, the cross-section is customarily planed and chamfered.
Drying, homogenizing and strength-grading leads to a dimensionally stable product with minimized cracking which shows moduli of elasticity parallel to the grain which are 10% higher than those of solid timber with otherwise identical permissible stresses and shear moduli.
