1. FW1035
Lecture 12
Bowyer et al, Chapter 13
Lumber Production

2. 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

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

4. 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

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

6. 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)

7. 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

8. 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)

9. 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)

10. 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

11. Nominal vs Actual Lumber Dimensions
Dimension Lumber
Nominal vs Actual Lumber Dimensions

12. 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.

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

14. 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

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

16. Ring Debarkers

17. Rosserhead Debarkers

18. 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

19. Band Saw Carriage Headrig

20. Circular Saw Carriage Headrig

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

22. Example of production from a “Gang Saw”

23. 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

24. Computer Controlled Optimization

25. 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

26. Sorting line at Sawyer red pine sawmill near Gwinn

27. Typical Lumber Drying Kiln

28. 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

29. 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