Technology Roadmap: Lumber and Value-Added Wood Products
5.7 Lumber Sorting and Grading

Existing Technology

A majority of hardwood mills rely on certified graders to grade and tally the lumber. In smaller mills, lumber tally and grade out-turn are recorded by the grader himself; mills with greater output use a separate grader and tally-man. Only a few mills have installed computerised systems to stamp the lumber according to the grader's decision, and to compile production statistics (for example, board footage and piece count) and to indicate to lumber stackers when it is time to strap the bundle and start a new one.

Sorting hardwood lumber is relatively easy as the lumber is either marked or stamped by the grader. The major challenge relates to stacking, which is still performed manually and requires several people. In many mills, the stacking operation is semi-automated; however, random lengths ranging from 1.2 to 4.9 m (4 to 16 feet) in random widths remain difficult to fit in regular package specifications (dimensions and volume content). It is also difficult for a mechanised system to "understand" that short lumber lengths have to be matched and placed end to end to produce a square bundle. Random widths also make it difficult to end up with a specific package size without exceeding the board footage content of a given bundle.

Incremental Technological Innovation

• Adapt or develop automated lumber sorters and stackers capable of producing square bundles for drying lumber in random lengths and random widths.
• Develop and implement hardwood grading systems based on automatic vision. Depending on mill circumstances, these could be semi-automatic (decision-aids) or fully automatic.

Breakthrough Technological Innovation

• Develop an integrated automatic system using multi-sensing devices to scan and grade hardwoods.