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Moisture Measurement in Primary Lumber Mills
A look at the importance of measurement and management of lumber moisture content, and resources available to view information on the lumber drying process.
By Ron Smith
Date Posted: 6/1/2013
Weexpect lumber to perform as specified, but the importance of measurement andmanagement of lumber moisture content is seldom understood outside the lumberindustry. Sawmills must integrate strict and continuous assessment of lumbermoisture at key phases of the manufacturing process in order to optimize thequality of the lumber. Inadequate management of lumber moisture can cost asawmill operation many hundreds of thousands of dollars per year.
Incoming: Sorting of“Green” Lumber in the Sawmill
Althoughnot done as routinely as it should be, pre-kiln sorting of lumber by moisture(and sometimes total density) can optimize dry kiln schedules for dryinglumber. Green sort lumber systems are designed to assess green lumber moistureand/or total density from which decisions can be made regarding whichdriability category (fast, medium, slow) each piece of lumber belongs in.
Thereare three distinct advantages of green sorting. First, green lumber sortingallows for accurate categorizing of lumber for kiln drying, which enables kilnoperators to more accurately determine drying times. Second, overall dryingtimes can be reduced when green sorting allows all of the fast-drying lumberpieces to be dried together, rather than being mixed with packs of slow-dryinglumber. Third, green sorting also decreases the occurrence of drying-relatedlumber degrade due to over-drying or under-drying. When lumber mills applygreen sorting technology at the start of the process, the positive financialbenefits begin to accrue almost immediately.
The Drying Process: In-Kiln Moisture Measurement
Lumberquality control (QC) is especially crucial in kiln drying systems. Advancedtechnology has existed for a number of years that permits kiln operators toplace moisture measurement probes inside lumber packages within the kiln. Thesemoisture-sensing probes send real-time moisture data directly to kiln dryingcontrol software running on a personal computer, where kiln operators canmonitor moisture content in their kilns in real-time. Operators can developmoisture-based drying schedules to allow better quality and more efficient kilndrying, and to better determine the optimum point at which the drying processshould stop. In-kiln moisture measurement systems can also reduce the need formanual “hot checks”. In essence, the moisture content management at thisdrying stage of the process augments the mill’s profitability with enhancedprocessing efficiency.
Planer Mill: In-LineMoisture Measurement of the Dried Lumber
In-Linemoisture measurement systems in the planer mill are the most important toolsfor capturing moisture data for every piece of lumber, allowing quality controlpersonnel, especially related to kiln drying, to have the critical data to helpimprove the kiln drying process. Without these systems, mill personnel are verylimited in their ability to accurately analyze their drying process.
Ifmoisture tracking is a science, internal lumber processing moisture systemsprovide the crucial data from which the art of optimum drying can operate.
Kilndrying.org: APrimary Forest Products Forum
It isan historic era in which individuals tap into a seemingly-endless well ofinformation on almost anything of interest. The pickings are a little slimmerfor lumber professionals, because their business is so technical. But theconcept of lumber moisture is of colossal importance to the lumbermanufacturing industry.
New Places to Dig
Lumbermill personnel involved in the lumber drying process have a new place to digfor important information: the kiln drying forum at www.kilndrying.org. Theforum is a software-driven hub for a world of questions related to dryinglumber. This kiln drying forum has three professional experts to moderatequestions and provide guidance.
Thesite is sponsored by Wagner Meters for the purpose of matching members’questions with expert feedback on wood kiln drying issues.
Registeredusers create threads within wood drying topic areas, such as Dry KilnMaintenance, Stacking/Sorting Wood, Impact on Planing, Dry Kiln Control,Moisture Variability, Drying Defects, Stain Issues, Training/Events and GeneralDiscussion.
New Experts toQuestion
Kilndrying encompasses a wide variety of methods and process depending on thedimension and species of lumber being dried. That’s why Wagner Meters chosethree experts in a generous cross-section of industry and education.
Dr. Joe Denig: Professor– North Carolina State University
Dr. Denig holds a Ph.D. from VirginiaPolytechnic Institute and State University. At NCSU, Professor Denigcontributes both technical aid and leadership to the financial profitability ofthe primary wood products manufacturing industry. Dr. Denig’s projects rangefrom financial evaluations of mill upgrades, evaluating sawmill scanning andoptimization systems, to lumber drying technical assistance. He facilitateslumber industry round tables. Denig is a member of the Forest Products Societyand serves as Treasurer of the Southeastern Dry Kiln Club.
Dr. Mike Milota:Professor – Wood Science and Engineering, Oregon State University
Dr. Milota works on projects related todrying lumber and biomass. At OSU, Milota teaches a graduate course in woodscience, and an undergraduate class in manufacturing with renewable materials.Mike earned his Bachelor of Science (B.Sc.) in Forestry from Iowa StateUniversity, and he achieved his Masters and Ph.D. credentials at Oregon State.Dr. Milota is intellectual and practical. He has over a quarter-century offorest products industry experience. Mike is a registered professional engineerin Oregon, and he coordinates OSU’s Lumber Drying Workshop held annually inDecember.
Timothy Duncan,Manager – Engineering and Research-and-Development, Wagner Meters
Tim is primarilyresponsible for Research and Development in moisture measurement systems atWagner Meters. Tim earned his B.A. degree in Physics from the University ofCalifornia (Berkeley), and an M.B.A. from Capella University. Tim spent sevenyears as a Programmer/Analyst with UC Berkeley’s Electronics ResearchLaboratory before joining Wagner in 2006. Tim also developed a core metrologystatistical software suite for start-up OnWafer Technologies.
New Answers to OldQuestions
So, login to the primary forest products forum and join the universal conversation onkiln drying of wood. The lumber industry community awaits.
Ron Smith is the Sales Managerfor Wagner Meters. Ron has 30 years of experience in instrumentation andmeasurement systems in different industries. In previous positions, he hasserved as regional sales manager, product and projects manager, and salesmanager with manufacturers involved with measurement instrumentation used inthe water/wastewater treatment industries, power utilities, national testinglaboratories, forest products companies and flooring industry.
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