FW1035 Lecture 12 Bowyer et al, Chapter 13 Lumber Production

Sawmill Goals Maximize the value and yield of the primary final product (lumber) Maximize value and yield of secondary products (2006 numbers for softwood mills) Chips – 95% pulp Sawdust and planer shavings 59% - composite boards (e.g. particleboard, MDF) 25% - fuel 7% - animal bedding 4% - pellets Bark for horticultural mulch and fuel

Maximizing the total value of products from a log. Softwood Mills – large, highly automated, commodity-oriented Hardwood Mills – Smaller, labor-intensive, specialty-oriented

Today’s Mills Changing resource forced efficiency improvements Trend to smaller mills, more evenly distributed through resource area Closing of old mills; opening of new mills as resource availability changes Scanners and computer control are important steps now, especially in softwood mills High level of automation Reduced labor costs Waste has been dramatically reduced Can recover 70% of log volume as lumber from some logs (8-10 inch diameter class) Much greater emphasis on secondary products

Distribution of Softwood Sawmills in the U.S. and Canada

Softwood and Hardwood Lumber Production Distribution in the U.S. South (44%) the major producer of lumber (softwoods and hardwoods) West (36%) - mills produce more per mill, but fewer mills (mainly softwood) North and northeast - only 20% of US lumber (hardwood and softwood)

Commercial Softwood Lumber Use Uses (2003) 38% Residential houses and apartments 27% Repair and remodeling 2% Commercial low-rise buildings 33% Non-residential high-rise, manufacturing/industrial, pallets/crates, misc. Species Douglas-fir and southern pine (75%) Minor (but significant) species: Western white and sugar pines Ponderosa pine Western hemlock True firs

Commercial Hardwood Production High grades for furniture, millwork, floors Largest single use is pallet/crating production 27% of hardwood lumber Softwoods also used on west coast Railroad ties: 25 million produced annually (60% in the south) 80% of them from dense hardwoods (oak, maple, hickory)

Hardwood Species Most Harvested: Furniture Use: Red oak (single most important species group) White oak The gums Yellow poplar Maples Ashes Furniture Use: Red oak Black walnut Black cherry Hard maple Yellow birch Then the others (ash, gum, elm, yellow poplar)

Terminology Based on Thickness and Size Softwoods (Nominal Dimensions): Boards – 2 inch thickness or less Dimension – >2 to 5 inches Timbers – 5 inches or greater Hardwoods: “Dimension” - stock sizes for furniture or pallet manufacturing “Parts” – specific sizes needed for a particular furniture, millwork, window, etc. part

Nominal vs Actual Lumber Dimensions Dimension Lumber Nominal vs Actual Lumber Dimensions

Other Terminology Rough-Sawn Lumber – Unplaned/surfaced, non-kiln dried lumber, usually full nominal dimensions S4S – Surfaced (sanded) on four sides “Quarter” Thickness System - For rough-sawn lumber, thickness given in quarters of an inch. E.g. 4/4 = four quarter or one inch thick. Others: 5/4, 8/4, 10/4 etc. Board Foot - Rough sawn lumber is usually sold by the "board foot" (bd. ft.). A board foot is equal to a piece of wood 12 inches long x 12 inches wide and 1 inch thick, or 144 cubic inches.

The Sawmill Process Debarking Primary breakdown (Secondary breakdown) Edging and trimming Sorting to size Drying Planing Grading and re-sorting

Removes bark and dirt from the logs before they enter the process Debarking Removes bark and dirt from the logs before they enter the process Helps to limit saw dulling Adds value to chips and slabs Bark can be used as fuel, mulch, etc Enhances accuracy of shape scanning

Types of Debarkers Water jet (uncommon) Drum Ring Rosserhead High pressure water jet Drum debarker

Ring Debarkers

Rosserhead Debarkers

Primary Breakdown – “Headrigs” Two Basic Types: Carriage Headrig more common with hardwoods also large, high value softwoods time here is expensive - move to secondary breakdown Single Pass Headrig automated process softwood dimensional lumber plywood veneer bolt cores

Band Saw Carriage Headrig

Circular Saw Carriage Headrig

Single Pass Headrig - The ‘Chip-n-Saw’

Example of production from a “Gang Saw”

Secondary Breakdown and Optimization Re-sawing of boards coming off the headrig Cants from carriage cut into boards with a gangsaw Two types: circular saws band saws Optimization maximizes value yield

Computer Controlled Optimization

Sorting, Drying, and Surfacing Initial sorting into thickness and width classes Drying (kiln, air, or combination of both) Surfacing in a planer mill machined to final dimensions Grading Resorted for grade, species, and dimensions

Sorting line at Sawyer red pine sawmill near Gwinn

Typical Lumber Drying Kiln

Drying Lumber Hardwoods – no standard %MC Softwoods Range: 6-10% Frequently specified by customer Softwoods Green – wood was above 19% MC when surfaced (air dried) Dry or KD 19 – surfaced when wood was <19%MC KD 15 or MC 15 – surfaced when wood was 15%MC or less

Surfacing Stamped on boards Type of surfacing is based on intended use and customer preference S2S S4S Surfacing can be done green or dry S-Green S-Dry