How does a designer select a material and the stock form it is bought in?
Selecting materials by balancing function, aesthetics, cost, manufacture, availability and environment, and the standard stock forms (sheet, bar, rod, tube, extrusion, section, granules, powder, wire) that materials are supplied in and how stock form affects waste and cost.
A focused answer to Eduqas A-Level Product Design on selecting materials and stock forms: balancing function, aesthetics, cost, manufacture, availability and environment, the standard stock forms materials come in, and how choosing the right stock form reduces machining and waste.
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What this dot point is asking
Eduqas wants you to explain how a designer selects a material by balancing competing factors, and to know the standard stock forms materials are supplied in and how stock form affects waste and cost. Selection is where the whole materials topic comes together: it applies classification, properties, performance characteristics and processes to a real product, and it is heavily examined as extended, justified reasoning.
The factors in material selection
Stock forms
How stock form affects waste and cost
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20204 marksA designer can make an aluminium bracket from solid bar or from a standard extruded section. Explain two reasons why choosing the extruded section reduces cost.Show worked answer →
A Component 1 short-answer question. Two marks for each reason, or one each for two reasons.
Reason one: an extruded section is already close to the final cross-section, so far less material has to be machined away, which reduces both machining time and labour cost. Reason two: because less material is cut away, less is wasted, so the material cost per part is lower and there is less scrap to deal with.
Both reasons turn on the stock form being near-net-shape: less to remove means less time, less waste and lower cost. Award marks for two distinct reasons (machining time and material waste). A common dropped mark is giving two versions of the same point.
Eduqas 20226 marksDiscuss the factors a designer balances when selecting a material for a children's outdoor play product. Justify your reasoning with reference to a named material.Show worked answer →
A Component 1 extended question marked by levels of response. Reward balancing several selection factors for the product.
Function: weatherproof, strong, durable, non-toxic and safe (no sharp edges or splinters). Aesthetics: bright, appealing colours. Cost: affordable to make and buy. Manufacture: formable by the chosen process at the chosen scale. Availability: reliable supply in a usable stock form. Environment: ideally recyclable and durable to avoid replacement.
A justified choice such as rotationally moulded polyethylene (HDPE/MDPE) ticks weather resistance, safety (smooth, no splinters), bright moulded-in colour, suitability for hollow moulded forms, and recyclability. A top answer weighs the factors against each other and reaches a clear conclusion that no single factor decides, the material must satisfy function, safety, cost, manufacture and environment together.
Related dot points
- The classification of materials: papers and boards, natural and manufactured timbers, ferrous and non-ferrous metals and alloys, thermoplastic and thermosetting polymers, elastomers and composites, with named examples and typical product uses.
A focused answer to Eduqas A-Level Product Design on the classification of materials: papers and boards, natural and manufactured timbers, ferrous and non-ferrous metals and alloys, thermoplastics and thermosets, elastomers and composites, with named examples and typical product uses.
- The physical and mechanical properties of materials (strength, hardness, toughness, ductility, malleability, elasticity, plasticity, density, conductivity, durability) and how they govern the suitability of a material for a product, including the calculation of density.
A focused answer to Eduqas A-Level Product Design on the physical and mechanical properties of materials: tensile and compressive strength, hardness, toughness, ductility, malleability, elasticity, plasticity, density and conductivity, with definitions, the density calculation, and how each property governs material choice.
- Performance characteristics of materials (functionality, aesthetic, environmental, availability and cost factors), the difference between destructive and non-destructive testing, standard material tests (tensile, hardness, impact), and how test data supports material selection.
A focused answer to Eduqas A-Level Product Design on the performance characteristics of materials and how they are tested: functionality, aesthetics, environmental, availability and cost factors, destructive versus non-destructive testing, standard tensile, hardness and impact tests, and how test data supports material selection.
- The shaping and forming processes for polymers (injection moulding, blow moulding, vacuum forming, extrusion, rotational moulding), metals (casting, forging, die casting) and timber (laminating, steam bending), and how the process suits the material, the form and the scale of production.
A focused answer to Eduqas A-Level Product Design on shaping and forming processes: injection moulding, blow moulding, vacuum forming, extrusion and rotational moulding for polymers, casting and forging for metals, and laminating and steam bending for timber, with the material and scale each suits.
- Costing and quantities: calculating material quantities and waste, percentage and percentage change, nesting and yield, material and labour cost, profit and selling price, and break-even, with units carried through the working.
A focused answer to Eduqas A-Level Product Design on costing and quantities: calculating material quantities and percentage waste, nesting and yield, material and labour cost, profit, selling price and break-even, with worked calculations and units carried through.
Sources & how we know this
- Eduqas A Level Design and Technology specification (Product Design) — Eduqas (2017)