Lumber Processing Course: Manufacturing II Unit: Material ID
What is Lumber? • Lumber is various lengths of wood used in the construction and furniture making trades.
Steps In Producing Lumber • Starts with tree • Cut/debranched and sent to sawmill • Sorted and cut • Circular saw • Band Saw • Dried • Air • Kiln • Grade • Distributed
The Tree • Visual inspection • Size • Shape • Marked to be felled • *Felled – the process of cutting down a tree
The Saw Mill • After a tree is felled it is sent to the Saw Mill • at Saw Mill • Debarked • Grinder • Water jets
The Saw Mill Continued • Log cut to length or bucking • Log cut into strips the length of log • Plain Sawn • Quarter Sawn • Drying the lumber • Air Dry (10-12% Moisture) • Kiln Dry (6-8% Moisture)
The Saw Mill Continued • Lumber is Graded • Sent to Lumber yard to sold to you
Plain Sawn Lumber • Plain sawn wood is the type most typically seen today. When the log is cut in to planks all the cuts are parallel to each other.
Quarter Sawn Lumber • With Quarter sawn wood the log is first quartered (hence quarter sawn) and then diagonally from the center. • This results in a grain that is more vertical when looking at the plank end on.
Air Drying Lumber • To air dry the lumber is arranged in layers or courses • Separating stickers are place between boards and the boards are then stacked • Boards are stored outdoors so that atmospheric air can circulate through the piles and carry away moisture • Reduces moisture to about 10-12 percent.
Kiln Drying Lumber • Lumber is dried in a closed chamber • Controlling the temperature, relative humidity, and air circulation. • Wood reaches a predetermined moisture content. • Sevenpercent moisture – four to five days.
Wood Structure Radio Frequency (RF) • Heat waves, a unique technology utilizes electromagnetic waves • Radio Frequency spectrum to heat products within a vacuum controlled environment. • Heat wave kilns use amplifier based power generators to create the radio frequency field which heats each load. • Drying time for hardwoods – 24 hours.