Technology Roadmap: Lumber and Value-Added Wood Products
5.5 Primary Breakdown

Existing Technology

High Value Sawn Products

For higher-value species, such as maple, oak, birch and alder, the primary breakdown is performed on a carriage either with a single- or double-cut bandsaw. An operator aid is usually available to assist in the breakdown sequence but all of the quality decisions are operator-driven. Nonconventional logs (for example, small diameter or length under 2.4 m [8 feet]) are usually processed on an overhead carriage with an end-dogging system which holds the logs through a twin circular or a twin bandsaw headrig followed by a multiple circular resaw. High productivity is very important as these small logs offer little high-value lumber; for this reason, manufacturers go further in the manufacturing process and produce higher-value components rather than low-value lumber.

More advanced systems use scanning and optimisation systems either on a carriage (light curtain) or an end-dogging twin headrig with double-axis scanning to maximise product volume and value recovery. These systems are expensive and require qualified maintenance personnel; consequently very few hardwood sawmills can economically justify their installation.

Optimisation in hardwoods has to go one step further than is the case in softwood mills. In addition to the log positioning, log rotation and breakdown optimisation, hardwoods require that defect size, type and location on the log be an integral part of the optimisation process. Internal log scanning to determine defect location would be ideal but, given the size and quality of the hardwood resource processed, it is doubtful that such equipment would be economically justifiable by sawmills that have limited production capabilities.

Commodity Products

Aspen and poplar species are usually processed through sawmills using technology similar to that used in softwood lumber production, at least when the end products are studs or dimension lumber for building construction. Conversion practice, however, is related to the type of end-product rather than to the species, and it is not uncommon for aspen or poplar to be converted into components, in which case they would be processed in exactly the same manner as the "high-value" species.

Incremental Technological Innovation

• Develop and implement cost-effective optimisation systems for edging and trimming based on the same concepts as those used in, or suggested for, the softwood lumber industry.
• Develop and implement cost-effective product monitoring systems to provide quality control and feedback.
• Develop technology to process shorter (less than six feet, down to three feet) quality lumber for manufacturers who do not need longer raw material or for finger-jointing.
• Process lower grade logs into lumber that can be repaired at a later stage.