Design and Technology Flashcards

Design and Technology - Materials

Paper & Board

• GSM (Grams per Square Meter): Indicates the weight and thickness of paper. Paper is typically less than 200 GSM, card between 200-500 GSM, and board is above 500 GSM.
• Paper Sizes:
  • A0: Largest stock size (used for architecture drawings).
  • A2: Artwork, posters.
  • A3: Smaller artwork, D&T portfolios.
  • A4: Booklet, tracing paper, layout paper, labels.
  • A5: Postcards, business cards.
• Optical Properties:
  • Brightness: How white the paper is; reflects light.
  • Opacity: How much light can pass through.
  • Color.
  • Gloss: How shiny the paper is.
• Surface Properties:
  • Smoothness.
  • Finish.
• Strength Properties:
  • Tensile Strength (Stretch).
  • Bending Strength (Flexible).
  • Greaseproof.
  • Porosity: How much the paper absorbs moisture.

Paper Finishes and Treatments

• Coating: Applying a layer of china clay or chalk to achieve a smooth surface.
• Sizing: Applying a sizing agent to improve the paper's ability to absorb ink.
• Laminating: Sticking layers of thin card together.

Paper Selection Criteria

• Cost:
  • Newspaper: Cheap ($).
  • Photo paper: Expensive ($).
• Finish: How the material looks and feels.
• Strength: How strong the paper is; newspaper is weak.
• Brightness: How white the paper is, and how well it reflects light.
• Thickness: Thicker paper = card or board.

Differences Between Paper, Card, and Board

• Thickness: Measured in micrometers (µm). 1000 \text{ micrometers} = 1 \text{ mm}
• Weight:
  • Paper: < 200 gsm
  • Card: 200-500 gsm
  • Board: > 500 gsm
• Types of Paper:
  • Tracing Paper: Translucent, slightly thicker than layout paper; used to copy images.
  • Layout Paper: Translucent with a smooth surface; used for sketching and technical drawings.
  • Bleed-Proof Paper: Has a protective layer to prevent ink bleed; used for marker rendering.
  • Printer Paper: Smooth surface, ideal for general writing/drawing and use in printers/laser copiers.
  • Coated Paper: Limits ink absorption; used for photographic printing.
  • Watercolor Paper: Better resistance to wet media compared to cartridge paper.

Types of Board

• Inkjet Card: High-quality card treated for use in inkjet printers.
• Cardboard: Cheap, recyclable; suitable for packaging.
• Whiteboard: Strong, bleached, great for printing.
• Duplex Board: Cheaper alternative to whiteboard; brown on one side, two layers with different finishes; used for food packaging.
• Corrugated Board: Corrugated core gives thickness and strength; used in cardboard boxes and cards.
• Bleached Card: Chemically brightened.
• Duplex Card: Two layers with different colors/materials; used for greeting cards and food packaging.
• Foil-Backed Card: Card with a metallic surface; used for takeaway food lids.
• Metal Effect Card: High-quality card with a metallic finish; used for credit cards.
• Lenticular Card: Creates a holographic effect when tilted; used in gift packaging.

Board Treatments

• Lamination: Polymer attached to one or both sides; used for drink packaging.
• Laminated Board: Improves properties, e.g., polyethylene/aluminum lamination.

Board Applications

• Mounting Board: Thick and lightweight; used for signs.
• Foam Board: Foam core with white outside layers.
• Coloured Cardboard: Used where rigidity is needed; suitable for boxes and board games.
• Corrugated Cardboard: Layer of card with corrugated core; several layers thick.

Composite Materials

• Definition: Mix of two or more materials to get better properties.
  • Example: Concrete = Cement + Sand + Water + Stone.
• Key Parts:
  • Matrix (Glue): Holds everything together.
  • Reinforcement (Strengthener): Makes it strong (e.g., steel bar in concrete).
• Types:
  • Fibre-based.
  • Particle-based.
  • Sheet-based.

Fibre-Based Composites

• Reinforced with fibre (wood pulp/GRP layer/chip).
  • GRP (Glass Reinforced Plastic).
• Examples:
  • Glass Reinforced Plastic (Glass + Plastic) - boats/cars.
  • Carbon Reinforced Plastic (Carbon + Plastic) - Formula 1/race cars.
  • Kevlar - bulletproof vest.

Particle-Based Composites

• All bits of particles mixed together.
• Examples:
  • Concrete: Cement + Sand + Stone (bridges/buildings).
  • Cermet: Ceramic + Metal (cutting tools).

Sheet-Based Composites

• Layers glued together (laminate).
• Examples:
  • Plywood: Layers of glue at 90-degree angles; stronger than wood for construction.
  • Veneer Lumber (LVL).

Properties of Composite Materials

• Strong but lightweight - used in planes/race cars.
• Corrosion resistance - won't rust (GRP used in boats).
• Good memory shape - can be molded to any shape.
• Durable - lasts long term (concrete).
• Waterproof - GRP great for boats.

Making Composite Materials

• Lay-Up Process:
  1. Prepare: Clean surface, gather materials.
  2. Cutting: Cut composite fibre to shape.
  3. Layering: Add fibre (glass/carbon).
  4. Resin: Add resin (glue) to fibre.
  5. Consolidation: Roll/brush to remove air bubbles and ensure even distribution.
  6. Cure: Leave to harden.
  7. Trim: Cut off excess.
• Spray-Up Process:
  1. Prepare: Clean mould.
  2. Spray: Resin and chopped fibres onto mould.
  3. Roll: Remove air bubbles, ensure strong bond.
  4. Layering: Add more layers to achieve thickness/strength.
  5. Trim: Remove excess.

Pultrusion

1. Pull fibre from spool (long shape).
2. Coat them in liquid resin.
3. Arrange fibers into shape.
4. Pull fibre into hot mold to harden.
5. Cool it down.
6. Cut it off.

Filament Winding

1. Fibre pulled by spool.
2. Fibre pulled though resin bath.
3. Fibre wrapped around a spinning mandrel (wrap fibre tight).
4. Control fibre winding (tension, position).
5. Curing: Heated to harden.
6. Remove mandrel.

Advantages of Composite Materials

• Light but strong
• No rust
• Moulded any shape
• Last long
• Waterproof

Disadvantages of Composite Materials

• Expensive
• Slow to make
• Hard to recycle
• Brittle (snap under heavy load)

Smart Materials

• Respond to changes in the environment (e.g., light intensity).
• Change physical properties accordingly.
• Changes are reversible, returning to the original state once the stimulus is removed.

Modern Materials

• Newly developed materials created through new manufacturing processes.
• Unique properties.
• New, advanced, more effective products.

Materials Comparison

Types of Smart Materials

• Shape Memory Alloys: Material returns to its original shape when exposed to electrical/heat.
• Thermochromic Pigment: Material that changes color in response to changes in temperature (e.g., baby spoon).
• Photochromic Material: Material that changes color when exposed to UV light (e.g., photochromic sunglasses).
• Phosphorescent Pigment: Glows in the dark after absorbing light energy (e.g., safety signs).
• Electroluminescent Wires: Emit light when powered by electricity (e.g., signs).
• Piezoelectric Material: Generates electricity when pressure is applied (e.g., lighter/vibration sensor).
• Smart Textile: Textile with sensors and electronics to sense, react, and adapt (e.g., heated jacket).

Smart Fluids

• Liquids that change viscosity when exposed to magnetic/electric fields.
• Applications:
  • Shock absorbers.
  • Smart grease (for smooth, controlled movement in soft-close toilet seats).

Modern Materials

• Graphene: Simple layer of carbon atoms; super strong and lightweight.
  • Applications: Phone screens, batteries.
• Carbon Fibre: Lightweight and strong composite fibre.
  • Applications: Sports materials, cars, aircraft.
• Kevlar: Ultra strong, impact resistant.
  • Applications: Bulletproof vests.
• Polymorph Thermoplastic: Becomes moldable at low temperatures.
  • Applications: Prototypes, DIY projects.
• Liquid Crystal Display (LCD): Flat screen displays using liquid crystals.
  • Applications: Phones, TVs.

Other Modern Materials

• Fibre Optic: Strands of plastic or glass that transmit signals for data transfer.
  • Applications: Internet cables.
• Coated Material: Metal with a thin layer of protective material (e.g., zinc).
  • Application: Prevents rust/corrosion.
• Titanium: Strong, lightweight metal that resists corrosion.
  • Applications: Aerospace, medical implants.
• Precious Metal Clay: Clay-like material made from precious metals (silver/gold).
  • Application: Jewelry.
• Glulam (Glued Laminated Timber): Made by gluing layers of timber together.
  • Properties: Beams strong, durable.
• Dichroic Glass: Glass displaying different colors at different angles.
  • Application: High-end jewelry.
• Metal Foam: Metal with air-filled pores; lightweight, crash protection.
  • Application: Car bumpers, strong sound insulation.

Manufacturing from Glass

• Glass Recycling:
  1. Lime Soda Glass: Mixture of sand, lime, and sodium.
  2. Cullet (recycled glass) heated to 1500 degrees.
  3. Result: Molten material formed into a continuous flow on molten tin.

Shaping Glass

1. Glass Blowing: Manufacturing hollow objects such as bottles.
   • Mouth blowing: Traditional, more expensive glassware.
   • Forced by pressing and blowing into molds.
2. Slumping: Glass heated until soft then molded (e.g., curved screens).
3. Annealing: Controlled heating and cooling to reduce stress.
4. Finishing: Cutting, coating, polishing.

Properties of Glass

• Mechanical Properties:
  • Brittle: Breaks easily under stress, shatters.
  • Hardness: Resistance to scratches and wear.
• Optical Properties:
  • Transparency: Highly transparent, allows light to pass through.
• Thermal Properties:
  • Insulator: Poor conductor of heat.
• Chemical Properties:
  • Chemically resistant/Non-reactive: Resists chemicals, does not corrode.

Types of Glasses

• Soda Lime Glasses: Soda, lime, sand; low cost, easy to form, transparent.
  • Applications: Bottles & jars.
• Borosilicate Glasses: Boron + silicate; heat resistant.
  • Applications: Beakers, lab glassware.
• Tempered Glass: Heat-treated for strength (specific heating/cooling methods).
  • Applications: Safety glasses, car windows (shatters into small blunt pieces).
• Laminated Glass: Layer of glass with plastic interior.
  • Properties: Strong, safety glass; holds together when shattered.
  • Applications: windscreens.

Specialized Glasses

• Self-Cleaning Glasses: TiO_2$$ (Titanium Dioxide) layer:
  • Breaks down organic dirt using UV light.
  • Allows water to spread evenly, washing dirt away.
  • Applications: Smartphone screens.
• Colored Glasses: Color introduced during manufacturing.

Glass vs Polymer

Ceramics

• Non-metal, inorganic material made from high-temperature processes (made of clay).
• Used for engineering ceramics and house bricks.
• High temperature applications.

Types of Ceramics

• Alumina (Al2O3): Cutting tools.
• Beryllia: High-frequency electronics.
• Magnesia: Furnace linings.
• Zirconia: Rocket nozzles, furnace insulation.

Slip Casting

1. Create liquid clay mixture (slip).
2. Pour slip into plaster mold.
3. Remove excess slip.
4. Let the clay harden, then remove from mold.
5. Fire in kiln to finish.

Textiles

• Flexible material made of fibres.
• Types:
  • Natural Textiles (Plant + Animal).
  • Synthetic Fibres (Polymer).

Natural Textiles

• Plant-Based:
  • Cotton: Soft, breathable, absorbent; used for clothing.
• Animal-Based:
  • Wool (from sheep): Insulation, moisture absorbent.
  • Silk: Smooth, luxurious.

Synthetic Fibres

• Polyester: Durable, sportive, non-absorbent.
• Nylon: Strong, silk-like, elastic, abrasion resistant.
• Acrylic: Lightweight, soft, warm.