Wood Quality & Appearance Mill Issues

Transcription

1 Wood Quality & Appearance Mill Issues Scion WQ Workshops 2014 Graeme Young Forest & Log Supply Manager Tenon Manufacturing Ltd. TENON - background Clearwood mill based in Taupo (Ex FCF). 370,000t/annum pruned log input. 3 shifts (cut a log every 50 seconds). Major moulding plant & secondary processing. Market into USA, Europe, Australia. 1

2 Key In-house WQ Knowledge Self 20 years at Scion (then FRI) working on WQ, then 10 years as FCF resource quality analyst 2 other staff with past Scion history in WQ area (20 years + 7 years) Wood Quality Issues Major Resinous defects Intra-ring checking Lesser Distortion/stability Density Heartwood content Minor Excessive resin canals Needle fleck/random fleck 2

3 Know your sources of variation Within tree (vertical trends, pith to bark) Between trees (natural variability due to breed, micro-climate etc.) Between sites (breed, climate, topography, silviculture) And then constantly monitor & record your key variables!!! In God we trust all others bring data! 3

4 Breed type by planting year Current harvest Hectares 6000 Super breeds Unimproved Year of establishment MAJOR - Resin a trees defence mechanism against damage or stress 4

5 Resinous defects My FCF resource history means I had a head start on understanding source issues in the CNI but WQI & SWI initiatives have identified key causes. Even if you don t have that most mills will monitor quality by source (essential) WQI validated Bernie s Kaituna Resin Assessment and I highly recommend it s regular use!! Resinous defects continued We record log end resin pocket counts from all of our log QC assessments. I have a weekly quality report from downstream remanufacturing which is a warning bell We strongly argue log price by source to discourage supply from resinous sources. Some forests I will not accept at all. 5

6 MAJOR - Intra-ring checking Intra-ring checking Ditto re FCF resource experience. Much of the early research on IC was carried out by FCF or Tenon. Where I have doubts about sources I request sampling before acceptance (another methodology developed by WQI). My fall back is trial loads which I will track and assess once dried. We look for green checks in log ends in every log QC not a warning bell though, this is an air-raid siren! 6

7 Intra-ring checking I get a quality feedback report after drying which allows me to id which logs were cut in the mill. We do some secret squirrel smarts in terms of log sorting by source and then process these differently. IC is age related. We will not cut logs younger than 25 years old. Ultimately I refuse supply from sources with issues. LESSER - Distortion 7

8 Distortion Distortion - is monitored in daily quality control measures in the processing centre and I get this feedback Shrinkage monitor skip at 1 st processing station. Seldom any issue Micro-fibril angle a butt log issue but only found within defect core. No issues. Spiral grain not a butt log problem. No issues. Compression wood our main distortion problem. Partially limited by log specs (sweep, wobble, fluting limits) Staff are trained to recognise severe CW and it can be ripped out where possible in down-stream processing A Tenon example severe compression wood 8

9 LESSER - Heartwood Heartwood The most significant factor in heartwood development is tree age. My greatest control on heartwood is ensuring growers are aware that increasing stand age is OK but if the heartwood develops beyond the defect core then this ultimately is the defect core. Occasionally we get short slugs of unusual heartwood from a single source. Typically stop before we can even react micro-climate effects! 9

10 LESSER - Wood Density simple resource sampling Which gives a new clearwood defect! 10

11 Density variability between sites and with age BHOBD, kg/m³ Age, years Density An unlikely issue in clearwood but the property with the best story. Highly variable and most influenced by genetics and source (climate etc.) We have customers who have occasional demands for both high & low density clearwood. 95% of my supply I obtain related BHOBD data for so I can easily react to specific requests with log separation for custom sawing to desired product. 11

12 Stiffness (density) case study Tenon was approached by Accoya who manufacture acetylated wood products. Acetylation process hardens and provides durability and stability similar to traditional durable high quality hardwood. The spec was for high stiffness clearwood to manufacture 2 major highway bridges. Identified potential resource Carried out sonic testing on sample logs to confirm Carried out irregular ongoing sonic tests as QCs. Sneek Bridge 12

13 Our supply had such structural integrity that a second bridge was commissioned and then this entrance to Dublin Uni. MINOR Excessive resin canals 13

14 MINOR Needle Fleck/random fleck MINOR Needle Fleck/random fleck 14

15 Final message Know your enemy and monitor it constantly. Don t rely on the eye-omiter. Rely on your measurements, records & data trends. React not to daily fluctuations but to bad trends. 15