Sawn wood and veneerbased

Transcription

1 CHEM-E0120 Sawn wood and veneerbased products Mark Hughes 30 th October 2017

2 Schedule: period II Date Time Content :15-10:00 Lecture: Sawn wood and veneer based products t.b.a :15-10:00 NO LECTURE :15-10:00 Lecture: Indoor air quality Hannu Viitanen :15-10:00 Lecture: Decay, pests and prevention Hannu Viitanen :15-10:00 Lecture: Wood products manufacturing: woodbased panels Mark Hughes :15-10:00 Lecture: Wood products and their applications Mark Hughes EXAM (Location: R011/A305/Ke1) EXAM (Location: R011/A304/Ke2)

3 Today Sawnwood Principles of production Veneer-based products Principles of plywood Principles of LVL 3

4 Sawmilling is about converting this (Source: commons.wikimedia.org) 4

5 to this (Source: commons.wikimedia.org) 5

6 (Source: commons.wikimedia.org) 6

7 What factors will be significant in this process? Raw material Species Form and dimensions Branches / knots Degradation / rot Etc, etc Product Dimensions Quality Application Price Etc, etc. 7

8 Phew! (Source: en.wikipedia.org) 8

9 The sawing process Shipping Storage Measuring Sorting Debarking Sawing Sawing Edging Presorting (Greensorting) Battening Drying Quality grading Packaging Source: Metsäteollisuus ry [online] [referred ] Available: Edited: Ulla Rintala 9

10 Harvesting (Source: vendiawoods-en.blogspot.com) (Source: 600) Harvesting in Finland: (Source: 10

11 Log scanning Ideally want to see inside the log in order to optimize the cutting to obtain the best yield of high quality material 3-D scanning (form) X-ray (internal structure) See: (Source: academics.concord.edu) (Source: integrated.co.nz) 11

12 Roundwood into rectangular boards Sawing method Sawing pattern Loss of wood All about optimization 12

13 Cutting optimisation 13

14 Sawnwood 14 (Source: Society of Wood Science & Technology)

15 Sawing patterns (Source: 15

16 The sawing method 16

17 The sawing pattern 17

18 Anisotropy Source: The wood Handbook

19 Sawing patterns 19

20 1 m 3 of round wood Yields (approximately): 45 % sawn goods 30 % chips 15 % sawdust 10 % bark 20

21 The sawing process Shipping Storage Measuring Sorting Debarking Sawing Sawing Edging Presorting (Greensorting) Battening Drying Quality grading Packaging Source: Metsäteollisuus ry [online] [referred ] Available: Edited: Ulla Rintala 21

22 Debarking of logs Logs are debarked so that byproducts (chips and saw dust) are not contaminated and can be used in other processes 22

23 Sawing - chipping 23

24 Sawing - profiling 24

25 Sorting, sticking and stacking After sawing, the wood is sorted into length and quality and then stickered (thin laths of wood inserted between planks to facilitate air flow and to restrain distortion) and stacked for drying 25

26 Ready for drying (Source: 26

27 Drying various methods Drying to reduce MC to near final EMC, reduce distortion etc. Various methods, including for example: Air seasoning Kiln drying, drying chambers or channels High temperature drying 27

28 Air seasoning 28

29 Kiln drying Warm air blown through the stack Temperature and humidity set to a particular drying schedule Temperature always under 100 C, usually C Two different kiln types: Batch kiln drying (chamber) Progressive kiln drying (channel) 29

30 Drying defects 31

31 Sorting Different qualities required for different products Sorting either visually or automatically Sorting rules are defined in standards 32

32 Packing and shipping 33

33 Further processing Grading Planing Finger jointing Gluing (glue laminated timber glulam ) Others (CLT etc.) 34

34 Youtube clips: Saw mill (short): Jg Saw mill (long): _g 35

35 Veneer-based products (Plywood, LVL and veneer)

36 Plywood has three main applications Transport boats trucks aeroplanes gas tankers -160 C Buildings Concrete forming

37 Other applications of plywood packing furniture interior decoration flooring products skate boards windmills ice-hockey rinks ice hockey sticks race cars floors

38 Types of plywood There are several hundreds of different types of plywood available in the World Variations in: o species (in Finland mainly spruce & birch) o thickness of veneers o thickness of final plywood o lay-up (cross-laminated, partly parallel, etc) o glues o surface coatings

39 Basic types of plywood (in Finland) Birch plywood usually made out of 1,4 mm birch veneers the toughest and most expensive light coloured and durable surface suitable for e.g. flooring Conifer plywood usually made out of thicker 2-3,5 mm spruce veneers lighter and slightly weaker than birch plywood suitable for e.g. roofing, walls and fences Combi plywood made out of birch and spruce veneers (every other veneer + surface is birch) properties between both plywood types: durable, quite light, easy to cut Thin plywood (Aircraft plywood) made out of special thin veneers 0,15-0,5 mm (for example birch) very tough and high bending strength suitable for e.g. miniature models, musical instruments, hockey sticks, business cards or designer wood products

40 Plywood properties Plywood in general has good properties when comparing to solid wood or some other materials (such as metals or concrete). Properties, however, depend on type of plywood The properties are such as: durable good resistance to wearing and loads good resistance to changing RH (when compared to solid wood) easy to clean, hygienic (with specific coating) odourles

41 The adhesives used affect the end uses Phenol-Formaldehyde (PF) adhesives, when weatherproof properties are required and price is crucial; concrete mould and truck floor board (most common) Urea-formaldehyde (UF) adhesives, when a colourless glue line is required, the product is used indoors and price is crucial; toys Melamine-formaldehyde (MF) adhesives, when a colourless and weatherproof glue line is required; use limited by relatively high price Melamine-urea-formaldehyde (MUF) adhesives, when colourless and weatherproof glue line is required; architectural use of veneer

42 Source: Suomen Metsäyhdistys ry [online] [referred ] Available: Plywood manufacturing in the Nordic countries Raaka-aineen hankinta ja kuljetus tehtaille Raw material supply and shipping Haudonta Soaking Kuorinta Debarking Katkaisu Cutting Viilun sorvaus Veneering Kuivaus Drying Leikkaus Cutting Lajittelu Sorting Liimaus Gluing Puristus Pressing Pre-pressing/cold Hot pressing (~150 C) Sahaus Sawing Hionta Sanding Lajittelu Sorting Pinnoitus Coating Puristus Pressing Pinkkaus Stacking

43 The biggest plywood producing countries China USA Malesia Indonesia Japan Brazil Canada Russia India Finland

44 The biggest plywood exporting countries China Malesia Indonesia Chile Brazil Russia Finland Canada USA Belgium

45 LVL: laminated veneer lumber

46

47 Laminated Veneer Lumber - LVL LVL has been available commercially for over 30 years LVL is made from sheets of spruce veneers usually thicker than plywood (3-4 mm) The veneers are chamfered(~5 cm) at the edges and combined into a continuous mat. In this way the length of the mat is not limited, unlike in plywood The exact positioning of joints and their distribution throughout the LVL cross-section is crucial LVL is produced and used in a variety of different lengths, thicknesses and widths, but one of the main products are structural beams for constructions

48 LVL beam production Side view Hot press Pre-press / cold press Lay-up 12 m From above Cutting to beams

49 LVL Products Beams All veneers are glued parallel to each other. The billet is cut to beams after gluing Thickness mm Width mm Length standard max 12 m (customised up to 24 m) Beams or boards Most veneers in parallel direction but a few middle layers perpendicular (but not every second like in plywood) Thickness mm Width 600, 900, 1200, 1600, 2500 mm Length standard max 12 m (customised up to 24 m)

50 Source: Puuproffa / Pro Puu Ry [online] [referred ] Available: Veneer manufacture Slicing Rotary peeling Staylog (semi-peeling)

51 Source: Reholz [online] [referred ] Available: 3D veneer Cross-laminated veneer stripes allow 3D-forming of veneers without breaking the veneer Very expensive Used mainly in furniture and decorative elements

52 Source: CWP Coloured Wood Products Oy [online] [referred ] Available: Through-coloured veneer The colour penetrates through the entire thickness of the material, and the surface can be renewed by sanding without loss of colour Very expensive Used mainly in furniture and decorative elements