1. LVL AS A CONSTRUCTION MATERIAL Figure1.41. Pre-pressing: the billet is cold pressed to spread the glue evenly between the veneers. Hot pressing is typically continuous to allow for variation in product lengths. The maximum LVL length (18-25 m) is limited either by the mill building or by delivery by road to the customer. Hot pressing must ensure that all glue lines reach the proper curing temperature. Once cured, the glue becomes resistant to melting and water insoluble, i.e. highly weather Figure1.42. Hot press. Figure1.43. Feeding LVL billets into 3-level hot press. resistant. With phenolic resins the pressing time ranges from 15 to 90 minutes depending on the thickness of the product. Long pressing times and high pressures cause the wood fibres to compress, resulting in higher product density. 1.6.5 Finishing The LVL panels are normally cut to size according to the width and length specifications of the customer. Additionally, the LVL can be sanded or otherwise treated. Some manufacturers use portal-type sawing units that enable inclined, diagonal or chamfered cuts. Finally, appropriate packaging protects the finished panels against soiling, moisture and handling damage, keeping them straight and easy to store and handle throughout the delivery chain from mill to customer. 1.6.6 Production summary The homogenous structure of LVL together with production process optimization enable a wide range of structures and products to be cut to size with virtually no raw material losses. The veneer peeling system ensures that the best properties of the veneer log are used with maximum efficiency. Production volumes have increased globally and availability is improving as new manufacturers emerge in the market. Demand for LVL is continuing to rise as residential construction and awareness of the environmental friendliness of wood products are increasing. More detailed production descriptions can be found in the Wood-based Panel Industry publication released by Finnish Woodworking Engineers' Association 2018 4. 32 LVL Handbook Europe
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