Production Aids With Metal Based Materials (AQA GCSE Design & Technology): Revision Note

The use of production aids with metals and alloys

• Production aids are used with metals and alloys when:

  • marking

  • cutting

  • drilling

  • bending

  • casting

  • joining

• Metal is often harder to correct after it has been cut or drilled

  • This means accurate marking out is especially important

• Aids may be made from steel or another durable material because they must resist wear from tools and repeated use

Measuring and reference points for metals and alloys

• A datum edge or datum surface is selected first

  • All important measurements are taken from this single reference to prevent small errors building up

• To mark dimensions and parallel lines on metal any of the following can be used:

  • Steel rule

  • Engineer's square

  • Scriber

  • Dividers

  • Callipers

• A scriber scratches a fine line into the surface of the metal

  • Engineers/Marking blue may be applied first so that the line is easier to see

• A centre punch creates a small indentation at the centre of a hole 

• The drill bit locates in the indentation instead of slipping across the metal

• Reference points may also be produced using coordinate measurements on a milling machine, CNC (Computer numerical control) machine or CAD/CAM system

• Allowances and tolerances are important where parts must fit together, such as a shaft fitting into a drilled hole

Templates and patterns for metals and alloys

• A template is placed on to sheet metal so an outline, hole position or bend line can be marked repeatedly

• Templates can be made from card for one-off work

  • Plywood, acrylic or metal templates are more durable for batch production

• A cutting template may guide a hand tool, plasma cutter, router or profile-cutting process,

  • Industrial templates need to withstand heat and wear

• Patterns are used in casting

  • This is where a pattern is a model of the required component that creates the mould cavity in sand or another mould material

• Casting patterns may include:

  • An allowance for shrinkage because metal contracts as it cools

  • A draft angle so the pattern can be removed without damaging the mould

• Templates and patterns improve consistency and reduce the time spent setting out each component

Jigs for metals and alloys

• A metalworking jig holds and locates the workpiece in a fixed position

  • It may also guide the cutting or drilling tool

• A drilling jig may contain hardened steel bushes,

  • This means the drill passes through the bushes so holes are produced in the same position and at the correct angle on every component

• A welding jig holds separate metal parts at the correct distance and angle while they are temporarily (tack) welded and before being permanently joined

• A bending jig or former controls the radius and position of a bend in wire, rod, tube or sheet metal

• Jigs reduce repeated measuring, improve safety and make components interchangeable in batch or mass production

• The jig must be rigid and securely clamped because if it moves or wears, every component produced after may contain the a fault