Veneer Production

Wood Figure

Veneer Production & Usage Veneers cut from various stem portions –(1) crotch –(2) trunk –(3) burl –(4) stump or butt

Process - In the Log Yard Logs tagged and tallied –Calculate volume –Inventory (tracking number) –Butts painted All logs must be kept wet –Sprinkler systems –Protect from drying out & cracking –Cracks = degrade = lost profit

At the Veneermill: Logs debarked –Debarker or water jet –Smooth out taper, remove imbedded rocks Logs transferred to saw –Ripped with band or circular saw Pict.: Ring Debarker

At the Sawmill: Logs processed –Faced –Ripped parallel to or through heart –Halved or Quartered Flitches banded together, heart to heart

The Cooking Vats: Banded Logs & Burls cooked in hot water vats –Soften fiber –Equalize color variation Temperature and schedule –Species and volume specific For example : White Oak (Quercus alba) Cook Time: 72 hours Water Temp.: 120º C

Flitch & Burl Prep.: After cooking…. –Burls pressure washed Remove mud & rocks QC inspection –Logs planed –QC inspection

Different Veneer Cutting Methods 1) Peeling – Rotary Cutting 2) Rotary Slicing –Rift cutting –Half-round slicing 3) Vertical/Horizontal Slicing –Flat slicing –Quarter slicing 4) Sawing Method

1) Peeling Peeling (Rotary Cutting): –Similar to a giant softwood lathe –Plywood production, burls, quilts and figured wood –Unripped log or burl held between dogs –Rotated around central axis…concentric rotary cutting

Peeling cont.

2) Rotary Slicing Another type of rotary cutting... –Eccentric (elliptical) rotary cutting –Called “rotary slicing” –Flitches are mounted on log beam –Elliptical rotation can be varied/adjusted –Produces extreme variation in grain

Rotary Slicing cont. Flat grain (Flat slicing) Vertical grain (Rift cutting) Flat grain

3) Vertical Slicing Slicing (vertical): –Flitch clamped on movable platen –Held in place with dogs –Pressure bar and knife fixed, perpendicular to platen stroke –Slicing done in up or down stroke Quarter Slicing Flat Slicing Quarter Slicing Flat Slicing

Horizontal Slicing Slicing (horizontal): –Flitch placed on fixed platen –Held in place with stays or dogs –Pressure bar and knife move over flitch –Knife and bar skewed….shear veneer from wood

Horizontal Slicing Method Flat grain Vertical grain

4) Veneer Sawing: –Veneer cut from cants –Employs a veneer re-saw, similar to band saw –Not usually used in high production environments –Low yield, but usually very high quality slices

Conditioning & Drying: Once cut, moisture must be removed from the veneer –Done to avoid warp, checks, color change and bacterial attack –Process is dependent on species –Final moisture content specified by customer

Conditioning & Drying: Conditioning (Natural or Slow Drying): –Veneer is placed in environmentally controlled rooms –Individually shelved –Lengthy drying periods –Very gentle to veneer –Results in high yield and quality

Conditioning & Drying: For example: Walnut burl requires 24 hour “breathing” before drying If not, veneer turns green in the dryer!

Conditioning & Drying: Drying (Synthetic or Forced Drying): –Veneer is feed through dryer on a metal screen conveyor –Dried under pressure and forced air –Operator can vary feed rate and final moisture content –Dryer is divided into three distinct sections: Conditioning Drying Cooling

Conditioning & Drying: Synthetic or Forced Drying: –Conditioning Initial moisture removed by high velocity air (90º to 120ºC) Screens “hold” veneer...only contact pressure –Drying Veneer heated with high velocity & temperature air (110º to 130º C) Screen press veneer flat to keep from warping

Conditioning & Drying: Synthetic or Forced Drying: –Cooling Veneer cooled with ambient high velocity air Screen pressure maintained At out-feed...veneer piled in packs of 16, 24 or 32

Trimming & Packaging: Piled veneer is trimmed in packs –Usually done with a large guillotine slicer –Packs trimmed “true” –Bundled & tagged

Trimming & Packaging: Operator grades untrimmed packs –Assesses best trim and highest yield –Must be informed of grade rules –Grade rules depend on customer

Trimming & Packaging: Once trimmed, packs bundled & banded –Packs inventoried according to log tracking number

Storage & Transportation: Shipping –Shipped packs shrink wrapped and banded on skids (pallets) –In some cases, packs banded between porous woods (poplar) to draw moisture away Packs usually shipped in sealed containers to ensure dry environment