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Features of Hardwoods

• Come from deciduous trees

• Generally strong, durable, and long lasting

• Uses: Furniture, flooring, + quality products.

Examples of Hardwoods

• Ash

• Beech

• Oak

• Mahogany

• Balsa

Features of Softwoods

• Come from coniferous (evergreen) trees

• Faster growing, less expensive, easier to process

• Uses: Construction, cheap furniture, everyday products.

Examples of Softwoods

• Pine

• Spruce

• Larch

Features of Manufactured Boards

• Made from bonded/compressed wood fibers

• Made from waste wood, low cost

• Very stable + consistent thickness

• Uses: Low-cost furniture, interior panels, construction

Examples of Manufactured Boards

• MDF

• Plywood

• Chipboard

Wood Markings

1. Wood grain

2. Annual growth rings

3. Knot

4. End grain

Features of Thermoforming Polymers

• Soften when heated, harden when cooled, can be reheated.

• Suitable for recycling.

• Uses: Mass-produced packaging + everyday applications.

Examples of Thermoforming Polymers

• Acrylic

• PVC

• PET

Features of Thermoset Polymers

• Set permanently once heated + can’t be reheated/reshaped

• Harder + more rigid

• Non-recyclable

Examples of Thermoset Polymers

• Epoxy resin

• Polyester resin

Composites Definition

A material comprising of 2+ different materials, resulting in a new material with improved properties or characteristics.

Examples of Composites

• Carbon fibre

• Fibre glass

• Concrete with reinforced steel (rebar)

Stage 1 - Felling

• Done using a machine called a feller buncher

• Operator called feller decides what trees to be cut

• Softwoods between 30-40 years are harvested, Hardwoods between 80-100 years.

• Done in winter - Trees contain less moisture

• Trees are delimbed + trunks are cut

• Felled trees are replaced with saplings - Maintain a sustainable source for the future.

Stage 2 - Storing/Transporting

• Logs stored in a clearing/forest until used at sawmill

• This allows some water in the tree to evaporate, lowering weight + cost of transporting and handling.

• Then cut into smaller lengths + picked up by a timber lorry

• This transports timber to a processing site (sawmill, paper mill)

Stage 3 - Conversion at Sawmill

• Logs are debarked + bucked or cut to specific lengths

• They are then cut into boards using circular saws or bandsaws - ‘conversion’

• 1st stage - Breaking down - Rough sawing

• 2nd stage - Re-sawing - More accurate cutting + finishing, like planing

• 2 types of rough sawing - through sawn + quarter sawn

• Ends of logs are trimmed + cur into boards

Stage 4 - Seasoning

• The removal of excess water/moisture

• When felled a tree has lots of water (up to 50%)

• 2 types of seasoning: Kiln + Air

• Kiln seasoning - Timber dried in a heated chamber - Expensive

• Air seasoning - Timber stacked in the open - Slower

• Seasoning = Less warping + deforming

• Unseasoned wood = ‘green wood’ - More likely to warp

Stage 5 - Preparing for Market

• Value can increase by manufacturing sawn timber - secondary processing

• When wood is made into more refined product - E.g. door or windows

• Treatment can be added for construction - E.g. fire resistance

Primary Processing of Polymers

1. Ground is drilled + it extracts and pumps oil to the land

2. Oil is pumped to a factory where it is turned into fuels + chemicals

3. Oil is turned into polymer pellets, melted to thick plastics, ready for molding.

4. Instead of landfill, old plastic can be recycled + turned back to pellets.

Resistor Colour Code

1. Band 1 - First Digit

2. Band 2 - Second Digit

3. Multiplier - How much to multiply by

4. (Tolerance - Tolerance of value)

Resistor Definition

Resists the current so that not too much voltage gets applied to a component, possibly damaging it.

Parts of a Speaker

• Copper voice coil

• Permanent Magnet

• Paper diaphragm

• Rubber surround

• Dust cap

• Frame

• Power supply

• Spider

How a Speaker Functions

1. The copper voice coil is placed inside a permanent magnet

2. When an alternating current flows through the copper coil, it creates an electromagnetic field around the coil

3. The magnetic field of the electromagnet interacts with the permanent magnet, causing the coil to be attracted + repelled repeatedly as the current changes direction.

4. This movement makes the voice coil vibrate back + forth very quickly

5. The coil is attached to the paper cone, so the cone also vibrates + pushes air to create sound waves.

6. The spider keeps the voice coil centered while allowing it to move back + forth

7. The rubber surround allows the cone to move smoothly while helping keep the speaker stable.

8. Low sounds are produced by slow vibrations (40Hz) while high sounds are produced by faster vibrations (thousands of Hz)

9. The power supply provides electricity for current to flow through the voice coil

10. The frame supports + holds all the components in place

11. Dust cap protects the inside of the speaker + voice coil from dust + damage.

What is a PCB?

PCB = Printed Circuit Board

2 PCB Sides

• Component side - Side with markings of components

• Track side - Side where you solder

Input, Output, Process

Input - Something that activates an output/starts the system

Output - The end result of a circuit

Process - How it turns an input to an output

What is a polarised component

Polarised - Has an anode (-) and cathode (+) and only conducts electricity in one way.

Method for Soldering

1. Plug in soldering iron + let it heat up, put it in the holder when not using it.

2. Wear goggles + ensure the are is well ventilated and use heatproof mat.

3. Clean tip of soldering iron on a damp sponge + place a bit of solder on the end for increased conductivity.

4. Insert component in component side of PCB, making sure legs are correct orientation.

5. Turn board to track side + bend legs to keep in place.

6. Place tip of iron on pad + component leg and heat for around 5 secs.

7. Touch solder to pad + leg.

8. Flux in solder helps clean + form volcano shape around pad.

9. Remove solder first then the iron + let pad cool.

10. Use wire cutters to trim the excess of the leg of the component.

Dry Joint Definition

When the solder between the pad + component can’t conduct if there is too little solder or they don’t reach. Or, if the pad or leg aren’t hot enough to melt to solder + create the joint.

Marking Out Tools

• Pencil - Make marks

• Steel Rule - Straight lines

• Tri-square - Right angles

Removing/Cutting Tools

• Woodworking vice - Clamp things in place

• Tenon saw - Straight cuts at 90 degree angle

• Bench hook - Keep things in place when sawing

• Sandpaper + Cork block - Sanding for smooth finishes

• Hand file - Sanding for smooth finished

• Scroll saw - More complex, machined sawing.

• Coping saw - More complex, hand held sawing

• Chisel + mallet - Trimming large portions

Drilling Tools

Pillar Drill - Drilling parts straight down

Hole saw - Drilling holes of different sizes

G-Clamp - Clamp things in place when drilling

Machine vice - Clamp metal in place

Shoulder Joint Method

1. Tenon Saw to cut straight down

2. Coping saw to cut diagonally cross

3. Chisel to trim remaining wood into square

Linear Design Process Explanation

Step-by-step method where each stage follows in order from context to evaluation. It starts with researching + initial ideas and moves to developing an idea + building a final design.

Linear Design Process Steps

1. Context

2. Research

3. Specifications

4. Initial Ideas

5. Development

6. Modelling/Prototyping

7. Final Design

8. Manufacture

9. Evaluation

Iterative Design Process Explanation

Cyclical process that involves repeating + refining stages to improve a design through feedback + testing.

Iterative Design Process Steps

1. Design

2. Prototype

3. Evaluate

CAD Definition

Computer Aided Design

CAD Advantages

• Quick + easy to draw + edit images

• Designs can be transmitted to clients via the internet

• High quality, accurate drawings

• 3D programmes allow different viewing positions/lighting

• Drawings can be stored on discs

CAD Disadvantages

• Understanding the applications can be time consuming

• CAD is unsuitable for initial designs

• Set up costs can include a high spec computer, printer, software, + training.

CAM Definition

Computer Aided Manufacture

CAM Advantages

• Machines don’t get tired = increased productivity

• Machines can work in hazardous environments that humans can’t

• Optimum feeds + speed = longer tool life

• Machines don’t need heat, food, etc.

• Operator error is eliminated

• Can reduce labour costs

CAM Disadvantages

• A CAM machine carries on making mistakes if programmed wrong

• Replacing workers increases unemployment

• Understanding applications fully can be time consuming

• High setup cost