Processing Raw Materials into Usable Stock

This lesson covers how raw materials are processed into usable stock forms, as required by AQA GCSE D&T (8552), Section 3.2.4. Raw materials as extracted from the Earth are not directly usable — they must be processed, refined, and formed into standard stock sizes and shapes before designers and manufacturers can work with them.

---

Processing Timber

From Tree to Usable Timber

Stage	Process	Purpose
1. Felling	Trees are cut down (harvested)	Obtain raw logs
2. Debarking	Bark is removed from logs	Prepare for sawing; bark is often used as mulch or biofuel
3. Sawing (conversion)	Logs are sawn into planks and boards	Convert round logs into flat, usable sections
4. Seasoning	Timber is dried to reduce moisture content	Prevent warping, shrinkage, and decay in the finished product
5. Planing and finishing	Surfaces are planed smooth; timber is cut to standard dimensions	Produce consistent, ready-to-use stock

Seasoning Methods

Method	Description	Time	Result
Air seasoning	Timber is stacked outdoors with spacers (stickers) between planks to allow air circulation	Months to years (rule of thumb: 1 year per 25 mm thickness)	Moisture content reduced to ~14-18%; suitable for outdoor use
Kiln seasoning	Timber is placed in a heated, humidity-controlled chamber	Days to weeks	Moisture content reduced to ~8-12%; suitable for indoor furniture and joinery

Standard Stock Forms of Timber

Stock Form	Description	Common Sizes
Rough sawn	Sawn but not planed; rough surfaces	Various cross-sections
Planed all round (PAR)	All four faces planed smooth	20x45 mm, 44x44 mm, 44x95 mm, etc.
Boards	Wide, flat pieces	Varying widths, typically 12-25 mm thick
Dowel	Round cross-section rod	6, 8, 10, 12 mm diameter
Mouldings	Shaped cross-sections (skirting, architrave, dado rail)	Standard profiles
Sheet materials	Plywood, MDF, chipboard in large sheets	Standard sheet: 2440 x 1220 mm

AQA Exam Tip: You should know the purpose of seasoning and the difference between air and kiln seasoning. A common exam question asks why timber must be seasoned — the answer is to reduce moisture content, which prevents warping, shrinkage, and decay after the product is made.

---

Processing Metals

From Ore to Usable Metal

Stage	Process	Purpose
1. Mining	Ore is extracted from the ground	Obtain raw ore
2. Crushing and grinding	Ore is broken into small pieces	Increase surface area for chemical processing
3. Concentration	Waste rock (gangue) is separated from the ore	Increase the proportion of metal compound in the material
4. Extraction (smelting)	Metal is separated from the ore using heat and/or electricity	Produce crude metal
5. Refining	Impurities are removed	Produce high-purity metal suitable for use
6. Alloying (if required)	Other metals/elements are added	Create alloys with improved properties
7. Forming into stock	Metal is cast, rolled, drawn, or extruded into standard shapes	Produce usable stock forms

Standard Stock Forms of Metal

Stock Form	Shape	Typical Materials	Common Use
Sheet	Flat, thin (typically 0.5-3 mm)	Steel, aluminium, copper, brass	Car body panels, enclosures, brackets
Plate	Flat, thick (3 mm+)	Steel, aluminium	Structural steelwork, shipbuilding
Bar (flat, round, square, hexagonal)	Solid cross-section	Steel, aluminium, brass	Machining stock, brackets, shafts
Tube (round, square, rectangular)	Hollow cross-section	Steel, aluminium, copper	Bicycle frames, furniture, plumbing
Angle	L-shaped cross-section	Steel, aluminium	Shelving brackets, structural framing
Wire	Very thin, round cross-section	Steel, copper, aluminium	Electrical wiring, fencing, springs
Extrusion	Complex cross-section (custom profile)	Aluminium (most common)	Window frames, heat sinks, curtain tracks

---

Processing Polymers

From Crude Oil to Usable Polymer

Stage	Process	Purpose
1. Extraction	Crude oil is drilled and extracted	Obtain raw fossil fuel
2. Fractional distillation	Crude oil is separated into fractions at a refinery	Obtain naphtha (the fraction used for plastics)
3. Cracking	Naphtha is heated to break large molecules into small monomer molecules	Produce ethylene, propylene, styrene, and other monomers
4. Polymerisation	Monomers are joined together to form long polymer chains	Create the raw polymer (polyethylene, polypropylene, etc.)
5. Compounding	Additives (pigments, stabilisers, plasticisers, fillers) are mixed with the polymer	Customise properties for specific applications
6. Forming into stock	Polymer is extruded, cast, or pelletised into standard forms	Produce usable stock forms

Standard Stock Forms of Polymers

Stock Form	Description	Typical Materials	Common Use
Pellets/granules	Small pellets for injection moulding or extrusion	Most thermoplastics	Raw material for manufacturing processes
Sheet	Flat sheets in various thicknesses	Acrylic, HIPS, HDPE, PP, PVC	Vacuum forming, laser cutting, fabrication
Rod	Solid round or square bar	Nylon, acetal, PTFE, acrylic	Turning on a lathe, machining
Tube	Hollow round section	PVC, PP, ABS, acrylic	Plumbing, electrical conduit, display
Film	Very thin, flexible sheet	LDPE, PP, PET	Packaging wrap, bags
Filament	Thin wire (typically 1.75 or 2.85 mm)	PLA, ABS, PETG, nylon	3D printing (FDM/FFF)
Foam	Expanded cellular structure	Polystyrene (EPS), polyurethane (PU)	Packaging, insulation, cushioning

AQA Exam Tip: The exam may ask you to identify suitable stock forms for a given manufacturing process. For example: "What stock form of polymer would be used for vacuum forming?" Answer: sheet. "What stock form would be used for injection moulding?" Answer: pellets/granules. Match the stock form to the process.

---

Processing Textiles

From Fibre to Fabric

Stage	Process	Purpose
1. Fibre preparation	Cleaning, carding (combing), and aligning fibres	Prepare fibres for spinning
2. Spinning	Fibres are twisted together to form yarn	Create continuous, strong threads
3. Weaving, knitting, or bonding	Yarns are interlaced, looped, or bonded to form fabric	Create usable textile fabric
4. Finishing	Dyeing, printing, waterproofing, fire-retarding, brushing	Customise appearance and performance

Standard Stock Forms of Textiles

Stock Form	Description	Common Use
Fabric roll (bolt)	Continuous roll of fabric, typically 1-1.5 m wide	Clothing, furnishings, upholstery
Yarn/thread	Continuous filament or spun fibre	Sewing, knitting, embroidery
Non-woven fabric	Fibres bonded together without weaving (e.g. felt)	Filters, insulation, craft
Pre-cut pieces	Specific shapes cut from fabric	Craft kits, repair patches

---

Summary