Resistant Materials – Properties, Characteristics and Suitability (IGCSE Design & Technology 0445)
1. How the Topic Fits into the Whole Syllabus
The Cambridge IGCSE Design & Technology syllabus is divided into Common‑Content (product design) and a Specialist Option – Resistant Materials.
These notes cover the specialist option in depth and also provide the required common‑content material, clearly linked to the three Assessment Objectives (AO1‑AO3).
1.1 Assessment Objectives (AO) – What They Assess
- AO1 – Knowledge & Understanding: Identify, describe and explain material properties, processes and their suitability.
- AO2 – Application & Analysis: Use knowledge to select, test and evaluate materials and processes; carry out practical work safely.
- AO3 – Evaluation & Communication: Communicate ideas clearly, justify decisions and evaluate outcomes against specifications.
1.2 Mapping of Notes to AO
| Section | Relevant AO(s) |
|---|
| Common‑Content Checklist & Design Process | AO1, AO3 |
| Control (feedback loop) | AO2, AO3 |
| Health & Safety | AO2 |
| Communication of Design Ideas | AO3 |
| CAD/CAM workflow | AO2, AO3 |
| Design in Society & Sustainability | AO3 |
| Material Types, Properties & Testing | AO1, AO2 |
| Preparation, Shaping, Joining, Finishing | AO2 |
2. Common‑Content Checklist (Product Design)
These items must be demonstrated in the design report for Component 2 (the project).
- Need analysis & design brief – identify the problem, target users, constraints and success criteria.
- Specification – translate the brief into measurable criteria (e.g., load ≥ 200 N, weight ≤ 500 g).
- Idea generation – brainstorming, mind‑maps, freehand sketches, rapid prototypes.
- Selection & justification – evaluate concepts against the specification and justify the chosen solution.
- Health & safety – recognise symbols, wear appropriate PPE, follow safe workshop practice.
- Communication – technical vocabulary, drawing conventions, exploded/assembly views, bill of materials (BOM).
- Use of technology – 2‑D CAD for layout, 3‑D CAD for visualisation, CAM for CNC/3‑D printing.
- Design in society & sustainability – consider economic, social, ethical and environmental impacts (cost‑benefit, ergonomics, sourcing, carbon footprint, end‑of‑life).
- Control – input‑processing‑output model with feedback to refine the design (see Section 4).
3. Project Preparation – Component 2 Checklist (Mapped to AO)
| Stage | What to Do | Assessment Objective |
|---|
| Identification | State the need, target users and constraints. | AO1 |
| Research | Gather data on existing products, materials, manufacturing methods. | AO1 |
| Specification | Write measurable criteria (strength ≥ X MPa, weight ≤ Y g, etc.). | AO1 |
| Idea Generation | Produce sketches, mind‑maps, quick models. | AO2 |
| Development | Develop the selected idea into detailed drawings and a CAD model. | AO2 |
| Planning | Create a work‑plan, list tools, materials, safety measures, time‑scale. | AO2 |
| Realisation (Make) | Follow the plan, record any changes, produce the prototype. | AO2 |
| Testing & Evaluation | Test against the specification, analyse results, suggest improvements. | AO3 |
4. The Design Cycle (A – F) – A Structured Approach
- Analyse the need – write a clear brief with success criteria.
- Research – market study, material properties, manufacturing methods.
- Develop ideas – sketch, model (physical or digital), select the best concept.
- Plan – detailed drawings, material list, tools, safety, timescale.
- Make – execute the plan, record changes, test during manufacture.
- Evaluate – compare prototype performance with specifications, recommend refinements.
5. Control – Feedback in the Design Process
The design process is a closed loop:
- Input – brief, specifications, research data.
- Processing – idea generation, planning, making.
- Output – the prototype or final product.
- Feedback – testing results, user trials, peer review, which feed back into a revised brief or design.
Including explicit feedback stages satisfies the “Control” requirement of the syllabus.
6. Health & Safety in the Workshop
- Key symbols – PPE, fire risk, restricted area (images omitted for brevity).
- General rules – keep the work area tidy, never work alone with dangerous equipment, inspect tools before use.
- Specific precautions
- Cutting – use guards, clamp workpiece, wear safety glasses.
- Drilling – secure material, select correct speed, wear hearing protection.
- Heat‑treating – ensure ventilation, wear heat‑resistant gloves.
- Laser cutting – never look directly at the beam, use appropriate fume extraction.
7. Communication of Design Ideas
- Technical vocabulary – tensile strength, modulus of elasticity, draft angle, etc.
- Drawing conventions – orthogonal projection, section cuts, dimensioning, scale.
- Bill of Materials (BOM) – component, material, quantity, supplier, cost.
- Exploded & assembly drawings – show part relationships and order of assembly.
- Report structure – brief, specification, research, design development, testing, evaluation.
8. Use of CAD/CAM
Typical workflow for a resistant‑material component:
- 2‑D CAD (e.g., AutoCAD) – produce precise layout drawings and dimensions.
- 3‑D CAD (e.g., SolidWorks) – visualise the part, check interferences, run basic stress simulations.
- Export files –
.dxf for 2‑D, .stl for 3‑D.
- CAM software – generate tool‑paths for CNC milling, laser cutting or 3‑D printing.
- Manufacture – follow the CAM programme, record any deviations for the evaluation stage.
9. Design in Society & Sustainability (Expanded)
- Economic impact – material cost, manufacturing cost, maintenance, life‑cycle cost.
- Social impact – ergonomics, accessibility, cultural acceptability, user safety.
- Ethical impact – sourcing of raw materials, labour conditions, fair trade.
- Environmental impact – embodied energy, carbon footprint, recyclability, end‑of‑life disposal, waste minimisation.
Use a simple life‑cycle diagram (raw material → manufacture → use → disposal) to illustrate how material choice influences each impact area.
10. Specialist Option – Resistant Materials
10.1 Types of Resistant Materials
| Category |
Typical Examples |
Key Characteristics |
| Metals (pure & alloys) |
Steel, stainless steel, aluminium, copper, brass |
High strength, good ductility, conductive, often need corrosion protection |
| Polymers (plastics) |
Polypropylene (PP), Polycarbonate (PC), ABS, PVC, Nylon |
Low density, corrosion‑resistant, variable impact & heat resistance |
| Composites |
Glass‑fibre reinforced polymer (GFRP), Carbon‑fibre reinforced polymer (CFRP), Fibre‑reinforced concrete |
High strength‑to‑weight, tailor‑able, often directional |
| Woods (natural & engineered) |
Hard species (oak, teak), Plywood, MDF, Particle board |
Renewable, good impact resistance, moisture‑sensitive, anisotropic |
| Ceramics & technical glasses |
Alumina, Silicon carbide, Borosilicate glass |
Very hard, excellent heat & chemical resistance, brittle |
| Smart / modern materials |
Shape‑memory alloys, Thermochromic polymers, Self‑healing composites |
Change properties in response to temperature, stress or light; useful for adaptive or safety‑critical products |
10.2 Key Material Properties Designers Look For (AO1)
- Strength – maximum stress before failure (tensile, compressive, shear).
- Stiffness (Rigidity) – resistance to elastic deformation; quantified by Young’s modulus (E).
- Hardness – resistance to surface indentation (Brinell, Rockwell, Vickers).
- Impact resistance – ability to absorb sudden energy (Charpy or Izod test).
- Wear resistance – material loss due to abrasion or erosion.
- Thermal properties – conductivity, coefficient of thermal expansion, heat‑deflection temperature.
- Corrosion / chemical resistance – behaviour in moist or aggressive environments.
- Density – influences weight and handling.
- Manufacturability – ease of cutting, shaping, joining, finishing.
- Cost & availability – market price, supplier reliability.
10.3 Comparative Property Table (Typical Values)
| Material |
Strength (MPa) |
Stiffness E (GPa) |
Hardness HB |
Density (g cm⁻³) |
Key Advantages |
Key Limitations |
| Hard wood (e.g., oak) |
40–80 |
10–15 |
30–70 |
0.6–0.8 |
Renewable, good impact resistance, easy to work |
Moisture swelling, property variability |
| Mild steel |
250–400 |
200–210 |
150–200 |
7.85 |
High strength & fatigue resistance, weldable |
Corrosion if unprotected, heavy |
| Aluminium alloy (6061‑T6) |
150–300 |
70–80 |
30–70 |
2.70 |
Lightweight, good corrosion resistance, machinable |
Lower stiffness than steel, lower wear resistance |
| Polypropylene (PP) |
30–40 |
1.5–2.0 |
20–30 |
0.90 |
Very low density, excellent chemical resistance, cheap |
Poor heat resistance, low stiffness |
| Polycarbonate (PC) |
60–70 |
2.0–2.4 |
80–100 |
1.20 |
High impact resistance, transparent, good dimensional stability |
Scratches easily, moderate heat resistance |
| GFRP (glass‑fibre reinforced polymer) |
200–350 |
20–30 |
50–80 |
1.8–2.0 |
High strength‑to‑weight, corrosion resistant, mouldable |
Complex manufacturing, lower impact than metals |
| Technical ceramic (Alumina) |
150–300 |
300–400 |
>200 |
3.9 |
Very hard, excellent heat & wear resistance |
Brittle, difficult to machine, expensive |
10.4 Measuring & Testing (AO2)
- Tensile test – yields ultimate tensile strength, yield strength and elongation.
- Hardness test – Brinell, Rockwell or Vickers; provides a surface‑hardness number.
- Impact test – Charpy or Izod; measures energy absorbed at fracture.
- Wear test – pin‑on‑disc or abrasion rig; reports wear rate (mm³ N⁻¹ m⁻¹).
- Thermal conductivity – guarded‑plate or hot‑wire method.
- Corrosion test – salt‑spray (ASTM B117) or immersion in acid/base.
- All results are compared with the product specification to decide suitability.
10.5 Preparation, Marking & Shaping Processes (AO2)
- Measuring tools – calipers, micrometres, rulers, protractors, depth gauges.
- Marking – centre‑punch, scribe, layout fluid, laser marking (plastics).
- Cutting
- Metals – bandsaw, hacksaw, abrasive cut‑off, CNC milling.
- Plastics – laser cutter, CNC router, hot‑wire cutter.
- Wood – hand saw, jigsaw, CNC router.
- Shaping
- Metals – turning, drilling, milling, grinding.
- Polymers – thermoforming, vacuum forming, injection moulding.
- Wood – planing, routing, sanding.
- Composites – hand‑lay‑up, filament winding, pultrusion.
- Heat treatment (metals) – annealing, tempering, quenching to modify strength and hardness.
10.6 Joining Methods (AO2)
- Mechanical fastening – bolts, screws, rivets, nails.
- Adhesive bonding – epoxy, cyanoacrylate, structural adhesives; surface preparation is critical.
- Welding – MIG/TIG for steel/aluminium, resistance welding for thin sheets.
- Soldering & brazing – for copper alloys and some plastics.
- Composite joining – co‑curing, stitching, adhesive film.
10.7 Finishing & Surface Treatment (AO2)
- Grinding & polishing – improve surface finish, reduce stress concentrations.
- Coatings – paint, powder coating, anodising (aluminium), galvanising (steel), UV‑cured resin (plastics).
- Heat‑setting – for thermoplastic parts to relieve residual stresses.
- Sealing – varnish or lacquer for wood, epoxy resin for composites.