LVLC technology and manufacturing production process and Grading inspection
Laminated veneer lumber has been available commercially for over 30 years. During this period its popularity has grown and the manufacturing process developed by Raute has proven to be the most reliable and most adaptable for a wide range of different production situations.
LVL is made from sheets of veneer. When these sheets are combined into a continuous billet of LVL, the effects of flaws in individual sheets are negated because they are spread throughout the cross-section of the billet, rather than being concentrated in specific locations, such as is the case with sawn lumber. For example, a flaw in a single sheet of veneer laid up into a 15-ply billet of LVL will effectively be 1/15.
These days, the challenge facing LVL producers is how to make the strongest possible LVL from their available raw material using smart grading techniques to sort their veneers.
LVL is produced and used in a variety of different lengths, thicknesses and widths. Raute’s LVL process is based on a combination of continuous lay-up and cycle-type hot pressing that is suitable for the production of LVL in all lengths.
Raute is recognized globally for its expertise in log handling technology. Log handling solutions are available for processing all commercial species, both hardwoods and softwoods.
Our wide range of log handling solutions are designed to satisfy the needs of our customers, regardless of their individual production needs or their production capabilities.
Raute log handling lines are specially designed for processing the raw materials used by plywood and LVL producers. They feature robust construction and reliable, continuous operation. The scope of the line, as well as the line configuration and the level of automation at which it operates, are determined in cooperation with the customer to ensure that it satisfies the prevailing needs and operating conditions in the best possible way.
Raute offers a wide range of peeling technologies to satisfy every customer’s requirements, regardless of how small or large their veneer production needs are. We offer peeling lines specifically designed for processing small diameter blocks, where accurate centering and clipping, together with high block handling capacity, are the most important factors. These same process benefits are also available for big block peeling and all other block processing needs.
Benefits that are common to all users of Raute peeling lines are optimum recovery, high capacity and the best possible veneer quality. The scope of the line and the level of automation involved are determined in cooperation with our customers so that their needs and operating conditions are satisfied in the best way possible.
Raute’s family of veneer drying products are renowned for their high productivity, energy efficiency and ability to produce high-quality veneer.
A drying line may be 4- or 6-deck in varying widths and capacities for drying a wide range of different wood species. A typical Raute drying system comprises all veneer feeding and unloading equipment, veneer handling equipment, a dryer that includes all heating components and process measuring devices and a process control system for controlling the entire line. In addition, both the RauteSelect and Raute Smart drying systems include grading lines complete with high-precision moisture measurement, defect detection and automatic dry veneer stacking.
Veneer scarfing for LVL
Raute’s LVL manufacturing process is continuous and offers a variety of construction types based on scarfed, overlap or butt joints.
Exact positioning of joints and their distribution throughout the LVL cross-section produces a strong product that meets industry standards.
The leading and trailing edges of each sheet of veneer are scarfed in order to provide a flush joint when the sheets are joined together on the layup line. Scarfing can be done in-line ahead of the glue applicator or off-line. Scarfed joints are a requirement of some markets because they eliminate gaps in the profile of the LVL and give a clean appearance.
Core veneer composing
The proper and efficient composing of veneer improves recovery and reduces labor costs associated with handling random veneer.
It also improves panel quality by eliminating core voids, while facilitating automatic layup be enabling lower-quality and random-width veneer to be assembled into full sheets. Additionally, veneer composing enables the flexible production of special-sized core veneers and plywood. This technology is particularly relevant in mills producing technical and overlaid plywood products.
Face veneer composing
The face veneer composing process utilizes face-quality full sheets, sheets that contain face quality veneer, pieces of random veneer as well as down-graded face grade veneers to maximize total face veneer volume.
Efficient face composing improves total veneer recovery and reduces random handling labour costs. Composing enables the flexible production of face veneers as well as the production of special-sized plywood panels. It also improves veneer quality as well as final panel quality and it facilitates the automatic layup of lower quality veneers. The composing of faces is usually a necessity in mills producing technical plywood, overlaid plywood and / or special-sized plywood.
The RauteSelect face veneer composing line requires one operator to oversee the defect clipping and composing process. This high production line offers several options with regards variable product sizes, the use of different wood species and layout configurations. Optional automatic functions are available in all areas of line operation for producing face veneer from face veneer quality veneers or randoms.
Raute is recognized globally for its expertise in patching technology, with patching solutions available to process all commercial hardwood and softwood species.
We offer a wide range of proven patching solutions, each designed to meet specific customer needs, regardless of the production needs might be. Patching lines incorporate user-friendly controls and are designed to operate at high capacity.
LVL Veneer grading
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.
A Mecano MVA or DMA moisture analyzer is used to 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.
A Meacno VDA colour camera is used to 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.
LVL lay-up and pressing
Raute manufactures LVL lay-up and pressing solutions to suit the specific production and capacity needs of the producer.
These range from manual lay-up lines feeding single-opening hot presses to high-capacity, fully-automatic lay-up lines feeding multi-opening hot presses.
For over 20 years, Raute’s step press technology has proven to be a reliable method for producing LVL that satisfies all international standards for strength and quality.
With Raute’s LVL technology, mills can produce LVL in commodity or customer-specified lengths and in all commercially requested widths.