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LVL & I-Joist Mill Optimization

  • The LVL and I-Joist models in PANELSIM™ allows the net revenue effects of various log supplies, and sales and operating strategies for an LVL and/or I-Joist mill to be explored. Most of the description of the plywood optimization application on this website applies also to LVL.


  • Other things being equal, and depending on species, large logs tend to have lower proportions of juvenile wood and sapwood than small logs, and thus produce veneer of higher average strength that requires less drying time on average. And the lathe productivity is higher. On the other hand there may be competition for the more desirable logs, and they are usually more expensive. It may be more profitable to use cheaper logs.


  • The PEELSIM™ program calculates the volumes of veneer that come from various grade zones at different distances from the log center, the amounts of heartwood and sapwood, and the peeling times, and how these vary with log and core size. Increasing the core size can divert more of the low-strength juvenile wood to other uses. The yields of various layup-veneer strength grades can be related to the production of veneer from each grade zone. The LVL model takes the costs of alternative log supplies into account, and can arrange things so that all the available lathe and dryer time is used, and takes the possibility of green and dry veneer sales and purchases of various grades at various prices into account.


  • Each LVL recipe specifies the number of sheets of veneer of each thickness, strength and appearance grade required to lay up LVL billets of various strength grades and thicknesses. Each recipe also has options governing the proportions of each veneer species and the amounts of composed veneer that may be used.


  • The layup and press rates for each of these LVL grades and thicknesses will be different, so different combinations of LVL grades and thicknesses require different ratios of veneer preparation and press time. It may advantageous to make species substitutions, and it will be advantageous to minimize downgrades of layup veneer. There will also be sales constraints on the amounts of different LVL grades and thicknesses that will be required, or sold at different prices. So there is plenty of opportunity for the LVL model to calculate the combinations of recipes, recipe options, veneer substitutions and downgrades, and productions of various LVL grades and thicknesses that make best use of the equipment that is available, and are the most profitable.


  • The model determines the marginal breakeven costs of producing various alternative LVL products, and various sensitivity analyses can be performed.


  • When there is an associated I-Joint plant the LVL model will model this as well, and take such things as sales demands for various I-Joist products into account.


  • When there is an associated plywood plant, there are rich possibilities for transfers and exchanges of various grades of veneer. In this case it will be appropriate to use a version of PANELSIM™ program which allows combinations of plywood and other panel plants, studmills and sawmills to be optimized.