Design and Technology (D&T) in the ECZ Senior Secondary curriculum bridges creative design thinking, mechanical engineering principles, and hands-on manufacturing skills. This comprehensive guide details orthographic drawing standards, materials classification, mechanism linkages, CAD/CAM applications, and portfolio design project execution.
Examination Overview:
ECZ D&T candidates sit for Paper 1 (Theory & Design Fundamentals), Paper 2 (Drawing & Graphic Communication), and complete a practical Design Project Portfolio realizable in wood, metal, or plastics.
1. Graphic Communication & Technical Drawing
Accuracy in drawing line weights and projection symbols is essential for scoring full marks in Paper 2.
Technical Drawing Standards:
- First Angle Projection Symbol: Cone truncated with small circle on left and large circle on right. Plan view is placed below front elevation.
- Third Angle Projection Symbol: Truncated cone with small circle on left and large circle on left (same side as view). Plan view placed above front elevation.
- Isometric Drawing: Axis lines set at $30^\circ$ to horizontal line. True dimensions are plotted along isometric axes; non-isometric lines are drawn by joining endpoints.
- Line Types (ISO): Continuous thick (outlines), continuous thin (dimension/hatching lines), hidden detail (dashed thin), center line (chain thin long-short-long).
2. Materials Science & Properties
Candidates must select suitable materials based on mechanical, physical, and aesthetic properties.
A. Timbers & Wood Products
Hardwoods: Broad-leaved deciduous trees (e.g., Teak, Rosewood, Mahogany). Dense, durable, used for fine furniture.
Softwoods: Coniferous trees with needle-like leaves (e.g., Pine, Cedar). Lighter, fast-growing, used for structural framing.
Manufactured Boards: Plywood (cross-laminated veneers), MDF (compressed wood fibers with resin), Chipboard (wood particles bonded under pressure).
B. Metals & Alloys
Ferrous Metals: Contain iron and carbon; magnetic; prone to rust (e.g., Mild steel, High carbon steel, Cast iron).
Non-Ferrous Metals: Do not contain iron; corrosion resistant (e.g., Aluminum, Copper, Brass alloy of copper + zinc, Bronze alloy of copper + tin).
C. Polymers (Plastics)
| Polymer Class | Properties | Examples & Applications |
|---|---|---|
| Thermoplastics | Re-soften when heated; recyclable; flexible molecular chains. | Acrylic (Perspex display cases), PVC (pipes), Polythene (packaging). |
| Thermosetting Plastics | Rigid cross-linked bonds; cannot be remelted once molded; heat resistant. | Melamine (laminate table tops), Epoxy resin (adhesives), Urea formaldehyde (electrical plugs). |
Workshop Safety Rule:
Always wear safety goggles when using drilling machines, lathes, or heat-shaping acrylic. Tie long hair back and ensure machine guards are locked before operation.
3. Mechanical Systems & Linkages
D&T candidates must analyze motion transfer mechanisms:
- Types of Motion: Linear (one direction), Reciprocating (back and forth in straight line), Rotary (circular), Oscillating (swinging back and forth in an arc).
- Cams & Followers: Cams (pear-shaped, eccentric, heart-shaped) convert rotary motion into reciprocating follower movement.
- Gears & Pulley Systems: Gear ratio formula: $\text{Velocity Ratio} = \frac{\text{Number of teeth on Driven gear}}{\text{Number of teeth on Driver gear}}$.
- Linkages: Four-bar linkages, push-pull linkages, and bell crank linkages ($90^\circ$ direction change).
Teacher Strategy Tip:
Use cardboard cut-out models with split pins to let students physically manipulate 4-bar linkages and observe input vs output motion directions during revision lessons.
4. Design Project Portfolio Execution
The ECZ D&T design project requires a structured design process folder:
- Problem Identification & Brief: Define the real-life problem faced by a target user (e.g., portable solar study lamp holder).
- Specification: List ACCESS FM criteria (Aesthetics, Cost, Customer, Environment, Size, Safety, Function, Material).
- Design Ideas: Produce 3-4 distinct annotated sketches showcasing creative solutions.
- Development & Modelling: Evaluate ideas against specification; build card/foam models to refine dimensions.
- Working Drawings: Produce fully dimensioned orthographic drawings with cutting lists.
- Realization & Evaluation: Manufacture the prototype in workshop and test against original specification with target user feedback.