1. UNIT 3 TECHNICAL MATERIALS WOODS

2. CLASSIFICATION WOODS NATURAL SOFTWOODS They come from coniferous trees. They are ever green, and have got NEEDLE shaped leaves HARDWOODS They come from decicious trees (they lost their FLAT leaves in autumm) MANMADE BOARDS

3. SOFTWOODS - PROPERTIES CONIFEROUS ARE FAST GROWING CONIFEROUS ARE FAST GROWING (20- 30 years to mature) TIMBER THAT COMES FROM CONIFEROUS TREES IS OPEN GRAINED TIMBER THAT COMES FROM CONIFEROUS TREES IS OPEN GRAINED IT SPLITS EASILY IT SPLITS EASILY IT IS WEAK IT IS WEAK IT IS CHEAP IT IS CHEAP

4. HARDWOODS - PROPERTIES DECICIOUS TREES ARE LOW GROWING (100 years to mature) DECICIOUS TREES ARE LOW GROWING (100 years to mature) TIMBER THAT COMES FROM DECIDIOUS TREES IS CLOSE GRAINED TIMBER THAT COMES FROM DECIDIOUS TREES IS CLOSE GRAINED IT DOES NOT SPLIT EASILY IT DOES NOT SPLIT EASILY IT IS STRONG IT IS STRONG IT IS EXPENSIVE IT IS EXPENSIVE

5. SOFTWOODS EXAMPLES

6. HARDWOODS EXAMPLES

7. HARDWOODS EXAMPLES

8. HARDWOODS EXAMPLES

9. BLOCKBOARD IT IS MADE FROM SOFTWOOD STRIPS IT IS MADE FROM SOFTWOOD STRIPS BONDED WITH AN ADHESIVE. BONDED WITH AN ADHESIVE. IT IS USED FOR FURNITURE MANUFACTURING IT IS USED FOR FURNITURE MANUFACTURING (internal parts) (internal parts)

10. CHIPBOARD IT IS MADE FROM SMALL CHIPS OF WOOD BONDED WITH A RESINE IT IS MADE FROM SMALL CHIPS OF WOOD BONDED WITH A RESINE IT IS USED IN FURNITURE MANUFACTURING. IT IS USED IN FURNITURE MANUFACTURING. IT IS CHEAP IT IS CHEAP

11. MEDIUM DENSITY FIBRE BOARD MDF = DM IT IS MADE FROM WOOD DUST AND RESIN, AND THEN PRESSURED INTO A BOARD. IT IS MADE FROM WOOD DUST AND RESIN, AND THEN PRESSURED INTO A BOARD. IT IS EASY TO WORK (machine, cut, paint...) IT IS EASY TO WORK (machine, cut, paint...) IT IS USED IN CHEAP FURNITURE (internal parts) IT IS USED IN CHEAP FURNITURE (internal parts)

12. PLYWOOD IT IS MADE FROM VENEERS OF TIMBER BONDED BY A RESIN. IT IS MADE FROM VENEERS OF TIMBER BONDED BY A RESIN. THE GRAINS OF THE VENEERS ARE PERPENDICULAR EACH OTHER. THE GRAINS OF THE VENEERS ARE PERPENDICULAR EACH OTHER.

13. WORKING WITH WOODS TO MEASURE & DRAW, WE USE... TO MEASURE & DRAW, WE USE...

14. TO CUT, WE USE...

15. TO HOLD, WE USE...

16. TO HOLE, WE USE...

17. TO SAND & RASP, WE USE...

18. TO JOIN, WE USE...

19. PHSICAL PROPERTIES The relationship The relationshipbetween MASS and VOLUME DENSITY The ABILITY The ABILITY of being sratched by other material HARDNESS

20. The property The property of resisting PULLINGforces The property of resisting PUSHINGforces TENSILE STRESS PULL PUSH COMPRESSION STRESS

21. The property of The property ofbeingBENT... The ability of The ability of resisting the action of living organisms, moisture... DURABILITY FLEXIBILITY

22. The ability The abilityto TRANSFER HEAT ELECTRIC CONDUCTIVITY THERMAL CONDUCTIVITY The ability to allow The ability to allow the FLOW OF ELECTRONS INSULATORS WOODS ARE GOOD THERMAL & ELECTRICITY INSULATORS