The species and environment of wood have a dramatic effect on the sharpness of knives and other cutting equipment. Certain woods are denser or naturally more acidic than others and thus dull blades faster. Soil composition also affects the acidity of the trees that grow in them. White oaks, for example, tend to have higher acidity in the Midwest (particularly Indiana) than other areas. The environment likewise affects density: long, cold winters produce trees with smaller, denser rings.
Understanding the characteristics of the wood your mill processes provides two advantages. One, it enables you to make better choices regarding equipment. You may want to consider a galvanized finish on your waste handling conveyors if your mill processes highly acidic woods, for example. Not adding a galvanized coating or otherwise installing a protective liner for such conditions may result in more maintenance and ongoing cost than your mill would spend on galvanization. A galvanized conveyor is thus be a better value under these circumstances than a lower-priced conveyor with a paint or powder coat finish.
The second advantage of understanding the characteristics of your wood is that it allows you to better plan for maintenance. Woods with higher acidity and density will dull blades faster, so you will have to sharpen them more often to achieve optimal performance. Because of this, you may want to consider knife guards to protect your knives and workers during blade changes. To reduce downtime, you may also want to consider a tool such as Raute’s micro beveller, which will hone knife edges while they’re attached to the machine.
Because maintenance will occur more often with denser and more acidic woods, you should furthermore seek out machinery that allows personnel to perform maintenance faster to minimize downtime. Certain cutterheads like those on our butt flare reducer have multifaced blades, which allow maintenance personnel to flip them once before sharpening. Our butt flare reducer further helps with maintenance by slowing the speed it rotates the logs when it senses a heavy load as will occur when the cutters dull. Slowing the turn speed allows the machine to continue to process logs without overloading the cutter system and thus reduces the urgency of maintenance.
Below is a chart of the average pH values and dried densities of common North American wood species. Use the chart for planning at your mill, and contact us with any needs regarding maintenance, processing, and waste handling. We have many years of experience and are happy to assist.
|Softwoods||Average pH||Average Dried Density||Hardwoods||Average pH||Average Dried Density|
|Alpine Fir||6||33 lbs/ft3||American Beech||5.5-6.2||45 lbs/ft3|
|Balsam Fir||5.4||25 lbs/ft3||American Black Ash||5.5||34 lbs/ft3|
|Black Spruce||5.7||28 lbs/ft3||American White Ash||5.4-6.0||42 lbs/ft3|
|Canadian Red Spruce||5.5||27 lbs/ft3||American White Elm||6.0-7.6||35 lbs/ft3|
|Douglas Fir||3.3||32 lbs/ft3||Balsam Poplar||6.4||23 lbs/ft3|
|Eastern Canadian Spruce|
|5.5||27 lbs/ft3||Black Locust||5.3||48 lbs/ft3|
|Eastern Hemlock||5.5-6.2||28 lbs/ft3||American Cherry|
|Jack Pine||5.4||American Mahogany||5.1-6.7||37 lbs/ft3|
|Pacific Silver Fir|
|27 lbs/ft3||Chestnut||3.6||30 lbs/ft3|
|Red Pine||5.2-6.0||34 lbs/ft3||Largetooth Aspen||5.8||27 lbs/ft3|
|Sitka Spruce||4.0-5.5||27 lbs/ft3||Oak||3.3-3.9||*45-47 lbs/ft3|
|Western Hemlock||4.8-5.4||29 lbs/ft3||Quaking Aspen||5.4||26 lbs/ft3|
|Western Red Cedar||2.9-4.0||23 lbs/ft3||Red Alder||5.9||28 lbs/ft3|
|Silver Maple||6.4||33 lbs/ft3|
|Striped Maple||6||32 lbs/ft3|
|Sugar Maple||5.1-5.8||44 lbs/ft3|
|Sweet Gum||5.2||34 lbs/ft3|
|Tamarack Larch||5.2||37 lbs/ft3|
|Yellow Poplar||5.2-5.4||29 lbs/ft3|
*Individual species vary. Specie density may be higher or lower than 45-47 lbs/ft3.
Acidity Source 2: http://www.wbpionline.com/features/ph-and-why-you-need-to-know-it/