laminated veneer lumber (LVL) – manufature production process

Manufacture

A schematic diagram of the manufacture of LVL .

The initial steps of manufacture of LVL are similar to those used in the manufacture of plywood. Typically, logs are rotary peeled on a lathe to create veneer sheets from 2.5mm (1/10″) up to 4.8mm (3/16″) in thickness. Veneer sheets are generally about 2640mm (104″) long by either 1320mm (52″) or 660mm (26″) wide.

The veneer sheets are dried, clipped to remove major strength reducing defects, and graded. The sheets are cut to the required width for the billet to be produced.

Manufacture of LVL

 

 

The individual veneers are then assembled with the grain of all veneers running in the long direction of the billet. End joints between individual pieces of veneer are staggered along the length of the billet to disperse any remaining strength reducing defects. The joints may be scarf jointed or overlapped for some distance to provide load transfer.

The veneer lengths are coated with a waterproof phenol-formaldehyde resin adhesive. The assembled billets are subjected simultaneously to pressure to consolidate the veneers, and to heat to accelerate curing of the adhesive. Once again, this aspect of the process is similar to that for plywood except that rather than being in a thin flat panel shape, the LVL material is formed into long billets up to 25m (80′) in length.

Once cured, the billets are sawn to custom lengths and widths as desired for the product end use.

Laminated Veneer Lumber (LVL) is a high-strength engineered wood product used primarily for structural applications. It is comparable in strength to solid timber, concrete and steel and is manufactured by bonding together rotary peeled or sliced thin wood veneers under heat and pressure.

laminated veneer lumber (LVL) panels are made from “peeler logs” in the same production lines as LVL beams. Engineered to precise design values and with a very high strength-to-weight ratio, LVL panels are suitable for structural wall, floor and roof applications. With increasing interest in mass timber use for diaphragm applications (floors, roofs, walls), manufacturers are beginning to position LVL in full sheet format, and some interesting configurations involve laminating LVL beams side-to-side to make thin, solid panels – exposing the veneer end grain instead of the face grain.

The LVL manufacturing process of veneering and gluing enables large members to be made from smaller trees, creating efficient utilisation of wood fibre. Scarf joints (chamfer cuts) create joints between sections of veneers. In typical manufacture, all veneers are laid up so the grain direction is the same in all veneers. In so-called ‘Q’ and ‘T’ lay-ups, some veneers are laid so that their grain is contrary to the grain direction most of the veneers, giving rigidity to the LVL so it does not warp and twist.

Our LVL Fabrication and Procurement Process

Meet the volume and quality requirements of any job. Machining and milling of holes is sometimes performed at the producers plant based on our carefully detailed fabrication drawings and CNC machine files, and the product is shipped straight to site. Other times the panels are shipped to our shop for further fitting of steel connections to speed up site erection.

laminated veneer lumber (LVL) product used in all types of construction projects.  Incredibly strong and dimensionally stabl, high strength from the homogeneous bonded structure.

The production process of   LVL, from peeling the tree trunks to dispatching the ready products.

Rotary-peeled softwood veneers that are glued together to form a continuous sheet,The sheet is cut to length and sawn into beams, planks or panels in according to customer´s requirements.

  • Strength: Ideal for high-load applications.
  • Ultrasonically graded veneers are arranged in specific patterns to maximize strength and stiffness
  • The veneers are bonded with exterior-grade adhesives under pressure and heat, resulting in low moisture content for dimensional stability

LVL
Available thicknesses: 1-1/2˝, 1-3/4˝, 3-1/2˝
Available depths: 3-1/2˝, 5-1/2˝, 7-1/4˝, 9-1/4˝, 9-1/2˝
11-1/4˝, 11-7/8˝, 14˝, 16˝, 18˝, 20˝, 22˝, 23-7/8˝
Available grades: 2.0E

LVL  Beam
Available thicknesses: 3-1/2˝, 5-1/4˝, 7˝
Available depths: 3-1/2˝, 5-1/2˝, 7-1/4˝, 9-1/4˝, 9-1/2˝,11-1/4˝, 11-7/8˝, 14˝, 16˝, 18˝, 20˝, 22˝, 23-7/8˝
Available grades: 2.0E

Laminated Veneer Lumber (LVL) is a high-strength engineered wood product used primarily for structural applications. It is comparable in strength to solid timber, concrete and steel and is manufactured by bonding together rotary peeled or sliced thin wood veneers under heat and pressure. LVL was developed in the 1970s and is today used for permanent structural applications including beams, lintels, purlins, truss chords and formwork. LVL can be used wherever sawn timber is used however one of the main advantages is that it can be manufactured to almost any length, restricted only by transportation to site.

Prior to lamination, the veneers are dried and the grains of each veneer are oriented in the same direction. This makes LVL stronger, straighter and more uniform than solid timber and overcomes some of timber’s natural limitations such as strength-reducing knots. This gives orthotropic properties (different mechanical properties against different axes) in a similar way to the properties of sawn timber, rather than the isotropic properties (the same mechanical properties in each direction) in the plane of plywood. The added durability of being an engineered wood product means LVL is less prone to shrinking or warping. LVL can also support heavier loads and span longer distances than normal timber.

Section sizes are then cut from 1200 m wide sheets or “billets”. The ability to cut different shapes from the LVL sheets allows for structural innovation using angular and curved shapes.

LVL provides a cost-effective and sustainable building material, delivering high structural reliability and strength.

Note: Some LVL members can be made with a few laminations laid up at right angles to enhance the shear strength of the member. These are known as Cross-Banded LVLs and may need to be specially ordered, as it is not a commonly stocked item.

Veneer used in the production of LVL is dried, graded and stacked, after which it is measured for moisture content and strength to ensure that it meets strength and stiffness standards and that it is of uniform quality.

Not all veneers are alike and with precise and proper grading, it is possible to optimize the use of this valuable raw material in the LVL end-product. Veneer density, grain orientation and the defects that are present all have an impact on the structural properties of the finished LVL. The LVL veneer grading technology available from Raute ensures that LVL with the best possible strength properties is produced.

Moisture content

measure the moisture content of the veneer sheets. Veneers containing too much moisture are graded out and only those with an acceptable moisture content proceed to the LVL lay-up line.

Density and strength

Ultrasonic sound propagation time and microwave technology is used to determine specific gravity and modulus of elasticity of each sheet of veneer. Veneers are graded into different categories according to their strength potential.

Visual defects

detect open defects and to analyze the overall visual appearance of each sheet of veneer. This data can be used in conjunction with the strength properties of the veneer to determine the final grade of the veneer and its position in the LVL lay-up.

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