Choosing the Right Technique
Before making a product or prototype, it's important to choose the correct technique for the material
and the task. Considerations include:
- The material being used (wood, metal, plastic, composite, fabric, etc.)
- The desired shape, strength, and finish
- The available tools and equipment
- Accuracy and tolerance requirements
- Health and safety implications
Wastage Techniques
Wastage involves removing material to shape the product. These methods are subtractive – material is
cut or drilled away and cannot be reused.
- Cutting: Done using saws (hand saws, band saws, laser cutters) or blades.
Suitable for wood, metal, and plastics.
- Drilling: Used to make holes in materials. Drill bits vary depending on
material type.
- Milling: A machine process where a rotating cutter removes material from the
surface. Used for detailed shaping of metal and plastic.
- Turning: Performed on a lathe where the material spins and tools are used to
remove layers, often for cylindrical parts.
- Sawing: Band saws or circular saws can make straight or curved cuts quickly in
bulk material.
Addition Techniques
Addition techniques involve joining materials together or building up layers. These are essential for
assembling parts and components.
- Welding: High-temperature process that fuses metal parts together. Common in
steel fabrication.
- Brazing: Similar to welding but uses lower temperatures and filler metal to
bond metals.
- Soldering: Used mainly in electronics and fine metalwork. Uses a soldering iron
and filler metal.
- Adhesives: Glues designed for specific materials (e.g. PVA for wood, epoxy for
plastic and metal).
- Fasteners: Screws, nails, bolts, rivets – allow for disassembly or strong
mechanical joints.
- Fusing (Textiles): Thermoplastic fabrics or fusible web used to bond layers
without stitching.
Deforming Techniques
Deforming processes reshape materials without removing any material. These often require heat or
force and are commonly used with metal and sheet plastic.
- Bending: Material is bent to a certain angle using tools like brakes or
formers. Used with metal sheets and wire.
- Folding: More precise than bending; creates crisp corners, often used in sheet
metal work.
- Rolling: Reduces thickness or changes shape by passing material through
rollers. Used in metal and plastic sheets.
- Press Forming: Shaping material in a die under pressure, used in automotive
panels and kitchenware.
Reforming Techniques
Reforming techniques use heat and/or pressure to reshape materials into new forms. Plastics are
especially suitable for these techniques.
- Vacuum Forming: A heated thermoplastic sheet is placed over a mould and vacuum
is used to suck it into shape. Used for packaging and product casings.
- Injection Moulding: Molten plastic is injected into a metal mould to form
complex shapes. Ideal for mass production of plastic components.
- Blow Moulding: Heated plastic tube is expanded using air pressure inside a
mould. Used to make bottles and containers.
- Compression Moulding: Preheated material is placed into a heated mould and
compressed. Common with thermosetting plastics.
Accuracy and Quality Control
To achieve high-quality outcomes, it is essential to work with accuracy and precision. This involves:
- Using marking out tools (e.g. rulers, squares, marking gauges)
- Measuring twice before cutting
- Following tolerances and design specifications
- Using jigs, templates, and moulds for consistency
- Testing and checking fit of components throughout the process
Safe Working Practices
When using specialist techniques and processes, safety is essential. Always:
- Wear appropriate PPE (Personal Protective Equipment) such as goggles, gloves, ear protection
- Use guards and safety features on machines
- Keep workspaces clean and free from trip hazards
- Understand risk assessments for tools and equipment
- Get supervision or training before using new machines or hazardous materials
Summary
Specialist techniques and processes must be chosen carefully based on material properties and the
intended function of the product. Using them effectively requires a balance of technical skill,
planning, and safety awareness. Mastering these processes will allow you to construct prototypes and
products to a high level of finish and functionality.
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