BEC JCE Design & Tech cheat sheet

Iterative design cycle: identify need, research, specify, generate ideas, develop, model/test, evaluate, refine.

A design brief states the problem and constraints; the specification converts it into measurable criteria (dimensions, cost, load, lifespan).

Design fixation is premature commitment to one idea; counteract with SCAMPER (Substitute, Combine, Adapt, Modify, Put to other use, Eliminate, Reverse).

Morphological chart crosses sub-functions with solution options to generate combinations systematically.

Decision matrices weight criteria (sum of weights = 1) and score options; highest weighted total wins.

Access FM prompts analysis: Aesthetics, Cost, Customer, Environment, Size, Safety, Function, Material, Manufacture.

Convergent thinking narrows to one solution; divergent thinking expands options; effective design alternates both.

Prototype fidelity trade-off: low-fidelity (paper, card) is fast and cheap for concept testing; high-fidelity tests real performance.

Hardness resists indentation/scratch; toughness resists impact without fracture; brittleness fractures with little deformation.

Stiffness is measured by Young's modulus E = stress/strain in the elastic region; higher E means less deflection for the same load.

Density ρ = mass/volume; specific strength = tensile strength/ρ, used to compare lightweight structures.

Thermoplastics soften reversibly on heating (PE, PP, ABS, acrylic); thermosets cure irreversibly (epoxy, polyester resin, melamine).

Ferrous metals contain iron (mild steel, cast iron); non-ferrous include aluminium, copper, brass, titanium.

Alloying and heat treatment alter properties: quenching hardens and embrittles steel; tempering restores toughness.

Composite rule of mixtures: a fibre/resin composite gains stiffness and strength along the fibre direction; properties are anisotropic.

Material selection trade-off: cost, availability, machinability, recyclability and appearance often conflict with strength-to-weight.

Personal protective equipment: goggles for all cutting/drilling, dust mask for MDF and composite sanding, ear defenders above ~85 dB(A).

Drill speed rule: harder material and larger bit diameter require lower spindle speed; plastics need low speed to avoid melting.

A chuck key must be removed immediately after tightening; never leave it in the chuck.

Machine guards and emergency stops must be functional before use; no loose clothing, hair tied back, no gloves near rotating tools.

Hand tool rules: cut away from the body, clamp work securely, keep blades sharp (a blunt blade needs more force and slips).

Electrical safety: RCD protection, PAT testing, no damaged leads; isolate power before changing blades or bits.

COSHH requires risk assessment and controls for dust, adhesives, solvents and resin hardeners.

Risk assessment: identify hazard, assess likelihood and severity, apply controls in order (eliminate, substitute, engineering, administrative, PPE).

Scale ladder: one-off, batch, mass, continuous production; unit cost falls with volume as tooling cost is spread.

Injection moulding suits high volume thermoplastics; tooling cost is high, so low volume is uneconomic.

Vacuum forming shapes thermoplastic sheet over a male mould; draft angle and radius are needed to release the part.

Laser cutting is 2D profile cutting with kerf width; design parts with slots for press-fit assembly.

3D printing (FDM) builds layers; anisotropy makes parts weaker across layer boundaries; overhangs need support.

Jigs hold work and guide the tool; fixtures locate and hold work without guiding; both improve repeatability.

Quality control: tolerance is permitted variation; go/no-go gauges give fast pass/fail; statistical process control monitors trends.

Lean principles: reduce the seven wastes, use just-in-time supply, poka-yoke (error-proofing) and standard work.

Third-angle projection: the view is placed on the side from which it is seen; first-angle places it on the opposite side.

Scale notation: 1:2 halves, 2:1 doubles; always state units and scale on the drawing.

Orthographic views required: front, plan (top) and at least one end elevation; hidden detail uses dashed lines.

Dimensioning rules: dimension lines outside the outline, no duplicate dimensions, do not dimension hidden features.

Line conventions: continuous thick for visible edges, continuous thin for dimension and projection lines, chain thin for centrelines.

Isometric drawing uses 30° axes with true lengths; oblique uses one face true shape with receding lines at 45°.

CAD benefits: parametric editing, layers, libraries, rapid export to CAM and rendering; drawbacks include licence cost and skill needs.

Physical modelling (card, foam, MDF) validates ergonomics and form; CAD renders communicate appearance but not structural truth.

Six Rs hierarchy: Rethink, Refuse, Reduce, Reuse, Repair, Recycle - recycling is low priority compared with reduction.

Cradle-to-grave analysis covers extraction, manufacture, distribution, use and disposal; life cycle assessment quantifies impacts.

Embodied energy is the total energy consumed in producing a material or product, often dominated by extraction and processing.

Design for disassembly: snap fits and reversible fasteners allow repair and material separation; adhesives and mixed materials hinder it.

Circular economy keeps materials in use; linear economy follows take-make-dispose.

Anthropometric data: use 5th percentile for reach, 50th for clearance and 95th for door heights; adjustability covers the range.

Ergonomic principles: neutral wrist posture, work at elbow height, avoid static loading and repetitive strain.

Inclusive design addresses extremes (age, ability, size) so the product works for the widest population without adaptation.

Project sequence: brief, research, specification, concept design, development, manufacture plan, making, testing, evaluation.

Manufacturing plan lists sequence of operations, tools, jigs, quality checks and time for each stage.

Test against the specification, not against personal preference; record quantitative results (dimensions, load, time).

Evaluation structure: strengths, weaknesses, fitness for purpose, suggested improvements, evidence from testing.

Photograph each stage of making to evidence process and support the evaluation.

Tolerance check: measure critical dimensions with calipers and compare against the drawing tolerance.

Client/user feedback is primary evidence; peer and expert feedback are secondary and should be triangulated.

Cost the final product (materials + bought-in parts + labour time) to assess commercial viability.