The global objective of the project is to investigate the feasibility of increasing bandmill production by proportionately increasing both the blade speed and the lumber feed speed. The objective of this phase of the project is to transfer the results of the laboratory experiments to the sawmill industry. The work described in this report covers the transfer of the technology to two sawmills. The first report has a more detailed introduction to the project and a review of the literature.
This paper describes observations made during a trip to Japan to study wood machining technology. Topics include highlights of the 12th International Wood Machining Seminar, the 32nd Nagoya International Woodworking Machinery Fair and several visits to Japanese companies. Wood machining technology in Japan (WP-OI 95.11) Copies available from Pacific Forest Centre, Canadian Forest Service, 506 West Burnside Road, Victoria, B.C. V8Z 1M5. Fax 604 363-0797.
Research into the cutting characteristics of bandsaws has shown that, in nearly every case studied, the average cutting path of the saw is biased to one side of the ideal cut path. This paper presents the results of a laboratory investigation into this off-centre cutting. The influences on the shape and cutting behaviour of bandsaws of such basic factors as bandmill strain, guides, guide alignment, and blade overhang, are measured. It is concluded that bandsaw blades are curved in the cutting region and angled slightly out of the cut. The curvature and angle of the blade are due to the interaction of the bandsaw with the bandmill wheels, in the presence of bandmill strain, overhang and wheel crown, and are relatively insensitive to bandmill strain or pressure guides. The curvature and angle of the blade in the cutting region are most likely the cause of the cutting bias.
Le rapport présente les résultats à la productivité et à la qualité de produits pour six usines satellites étudiés dans l'est du Canada. Un modèle de coûts est aussi contenu dans le rapport. Le coût au mètre cube d'un système de récolte par arbres entiers comprenant une usine satellite capable de produire des copeaux et des billes de sciage est comparé à celui d'un système comprenant une ébrancheuse-écorceuse-déchiqueteuse et une façonneuse à la souche et produisant les copeaux et les billes de sciage en forêt. Le modèle inclut les coûts de production pour la récolte, le transport routier et l'usine satellite.
This report describes the results of a mill test investigating the effect of a 15 degree alternate top bevel (ATB) tooth for bandsaws. The test involved comparing the sawing variation and surface roughness of Douglas-fir lumber cut by both ATB and standard saws. The test results showed no improvement in sawing accuracy with the ATB blades. In fact, as the blades became dull, the sawing accuracy of the ATB saws deteriorated faster than for the standard blades. Visual evaluation of surface roughness also indicated that the ATB saws produce slightly rougher lumber. However, this may be due to increased tooth bite associated with the ATB teeth. Further testing will be required to determine if the results of this test are truly representative of the performance of ATB bandsaws in general.
To document the current state of sawing performance in Canadian sawmills, a survey was carried out in 47 mills located in the major lumber producing regions of Canada: B.C., Alberta and Quebec. The survey was restricted to sawmills producing softwood lumber products, and to band and circular saws used for primary and secondary breakdown. Data characterizing sawing performance, as well as detailed information on saw and machinery specifications, were collected during visits to each participating sawmill. The results of the survey are presented in this report. Detailed specifications are given for band and circular saws, and sawing performance levels are discussed. The results of the survey show that considerable opportunities exist for improving the performance of both band and circular saws. The large range in saw kerf widths identified in the survey indicate that lumber recovery could be significantly improved by reducing kerf to the levels of the best machines. The performance of these machines demonstrates that thin kerf widths can be achieved while high production rates and small sawing variation are maintained. Specifications for the thinnest kerf machines are presented in the report and opportunities for improving sawing performance levels are also discussed. This report will interest sawmill managers, sawfilers and other mill personnel who want to know how the sawing performance of their mill compares to that in similar mills included in the survey.