1.2 Materials and there applications Flashcards
(46 cards)
What are the 5 main hardwoods
Oak Mahogany Beech Jelutong Balsa
What are the 4 main softwoods
Pine
Cedar
Larch
Redwood
What’s the difference between hardwoods and softwoods
Hardwoods: deciduous trees, expensive and slow growing
Softwoods: coniferous trees, cheaper and fast growing
Where are softwoods and hardwoods grown
Softwoods are made in North Europe and Northern America whilst hardwoods are grown in South America, Africa and South Asia (Equatorial Regions)
What are the two types of timber cuts
Quarter (Radial) Sawn
Through and Through
What is Quarter (Radial) Sawn
Log cut into quarters, then cut again. Produces good quality timber. more stable. More time consuming, and wasteful
What is Through and Through
Parallel slices: Quickest and cheapest method. Mainly softwoods. Some tangential, some radial
When cut how should wood be stored
Timber is Hygroscopic so it absorbs water in damp conditions and gives up water in dry conditions
Therefore the moisture level should be <14% for indoor use and <20% minimum to stop decay and increase resistance to rotting
What are the two seasoning techniques
Natural (Air)- stacked in open sheds
Artificial (Kiln)- Steamed, pressure and humidity reduced, heated and hot dry air is circulated
What is a Ferrous metal
A metal that contains iron
What happens when carbon is added to the metal
The metal becomes harder and more brittle
What is the advantages and disadvantages of Acrylic (PMMA)
A: Laser cut and machined well, can be polished, stiff hard plastic, durable and resistant to acid and weather
D: Brittle and scratches easy
What is the advantages and disadvantages of High Density Polyethylene (HDPE)
A: Excellent for moulding, less flexible than LDPE, can be sterilised, resistant to corrosion
D: Not recyclable, poor dimensional accuracy, difficult to bond, flammable, stress cracking
What is the advantages and disadvantages of Low Density Polyethylene (LDPE)
A: Soft and springy, tough, soft and flexible, good electrical insulator
D: Not recyclable and not as resistant to UV as HDPE
What is the advantages and disadvantages of Polyethylene Terephthalate (PET)
A: Semi-rigid, excellent barrier to chemical and gas, very low toxicity (food safe), tough and strong, good scratch resistance
D: very susceptible to heat degradation
What is the advantages and disadvantages of Polyvinyl Chloride (PVC)
A: Tough, either stiff or flexible, lightweight, good chemical resistance, can be welded bonded
D: Easily scratched, becomes brittle under UV unless stabilized to become uPVC
What is the advantages and disadvantages of Polypropylene (PS)
A: Inexpensive, light, hard, stiff, transparent, good water resistance
D: Brittle, low impact polystyrene breaks very easily, not strong
What is the advantages and disadvantages of Acrylonitrile Butadiene Styrene (ABS)
A: Excellent impact resistance, good resistance to chemical corrosion
D: Only available in opaque, poor weathering
What is the difference between thermoplastics and thermo-setting plastics
Thermoplastics can be remelted so it can be recycled whilst thermosetting cannot and therefore is worse for the environment
How is GPR made
Add gel coat to the mould Add the first layer of fiber Roll resin onto the fiber Let dry Repeat adding fiber and resin Take out of mould
What is the advantages and uses of Newsprint
Cheap, lightweight, uncoated
Used in newspaper
What is the advantages and uses of Layout Paper
Thin, slightly transparent
Used for sketches and tracing
What is the advantages and uses of Tracing Paper
Transparent
Used for tracing
What is the advantages and uses of Sugar Paper
Cheap, uncoated, variety of colours yet can fade
used for cheap mounting up of work
