Veneer Production - 2013 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 Quarter Slicing Flat 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