National Year 12 Design and Technology: Fashion and Textiles

1. 3.1 Technical principles (3.1.1-3.1.7)

3.1.1 Materials and their applications · 3.1.2 Performance characteristics of materials · 3.1.3 Methods of joining and use of components · 3.1.4 The use of finishes · 3.1.5 Enhancement of materials · 3.1.6 Modern industrial and commercial practice · 3.1.7 Digital design and manufacture

• Textile Fibres: Natural, Synthetic, Properties and Yarns – A textile fibre is a fine, flexible strand that is much longer than it is wide. Fibres are spun into yarns, and yarns are woven or knitted into fabrics. Natural fibres come from plants (cotton, linen – made of cellulose) or animals (wool, silk – made of protein). Manufactured fibres are either regenerated (viscose rayon, lyocell, made from wood cellulose) or synthetic (nylon, polyester, acrylic, made from petrochemical polymers). Each fibre's shape and chemistry give it properties: cotton absorbs water and is cool; wool is warm, springy and absorbs moisture; silk is smooth and lustrous; polyester and nylon are strong, crease-resistant and quick-drying but absorb little. Spinning twists fibres into yarn; blends such as polycotton combine good points of two fibres. Simple tests (burn test, microscope, water drop) help identify fibres.
• Fabric Construction: From Fibre to Fabric – Every fabric starts as fibres. A fibre's shape and chemistry decide how it feels and performs: cotton absorbs water, wool traps air and stays warm, polyester is strong and dries fast. Fibres are spun into yarns by twisting; more twist makes a stronger, smoother yarn. Different fibres can be blended in one yarn or mixed as different yarns in one fabric to combine their good points. Yarns become fabric by weaving (two sets crossing at right angles), knitting (loops linked together) or non-woven methods (fibres bonded directly). Smart textiles react to their surroundings, and technical textiles are made for performance, such as fire-proof or medical fabrics.
• Joining Fabrics: Seams, Threads, Interfacing and Fastenings – A seam is the line where two pieces of fabric are joined. The common seams are the plain seam (simple, most fabrics), the French seam (raw edges hidden, for thin fabrics), the flat-felled seam (two rows of stitching, very strong, for jeans) and the overlocked seam (fast, neat, good for knits). Thread holds the seam; polyester is strong and all-purpose, cotton suits cotton fabric, nylon suits stretchy or heavy items. Fusible interfacing has glue that melts under an iron to stiffen collars and cuffs. Fastenings such as buttons, zips, press studs and hook-and-loop let a product open and close. Designers choose seams and components by fabric, use, strength, safety, cost and look. Some synthetic fabrics are joined without thread by heat or ultrasonic welding or by adhesive.
• Surface Treatments and Finishes – A finish is a coating or treatment applied to the surface of a material. Finishes do two jobs: protect (against rust, rot, water, UV light, wear, stains, fire) and improve looks or feel (colour, shine, texture). Woods are painted, varnished, oiled, waxed, stained or treated with preservatives. Metals are painted over a primer, powder coated, galvanised with zinc, electroplated or, for aluminium, anodised. Many polymers are self-finishing from the mould, but can be polished or printed. Papers and boards are laminated or varnished. Fabrics get chemical or mechanical finishes such as water-repellent, flame-retardant, anti-crease or brushed, and laminated membrane fabrics keep rain out while letting sweat vapour escape. Choosing a finish means matching it to the material, where the product is used, its cost, how it is applied and its environmental impact.
• Textile Design: From Fibre to Patterned Fabric – Textile design is planning how a fabric is built and how it looks and feels. Fibres are spun into yarn; yarn is woven, knitted or bonded into fabric; then colour and pattern are added by dyeing, printing or stitching; and finishes give the fabric extra powers like water-repellence or crease-resistance.
• Production Methods – Firms choose how to make things by how many they need. One-off (job) production makes a single item to order; batch production makes a set of identical items, then switches; mass (flow) production makes huge numbers on a line; continuous production runs non-stop. Lean production and just-in-time cut waste and stock. Quality control checks products against a target size with a tolerance (for example 50 ± 0.5 mm), and quality assurance builds quality into every stage.
• CAD/CAM: Digital Design and Manufacture – CAD (computer-aided design) is drawing and testing a product on a computer as an exact 3D model. CAM (computer-aided manufacture) turns that model into instructions (a toolpath, saved as G-code) that a computer-controlled machine follows to make it. CNC milling and lathes cut material away (subtractive). 3D printers build up layers (additive). Laser cutters cut flat sheets. Using CAD and CAM together makes parts accurate, repeatable and quick to change, and lets designers make fast prototypes (rapid prototyping). The costs are expensive machines, training and less hand skill.