Design & Technology – Production techniques -Part 2

Source:http://www.bbc.co.uk/schools/gcsebitesize/design/resistantmaterials/processtechniquesrev1.shtml

Batch production tools

When making several identical products or parts, jigs, formers, templates, patterns and moulds are used to ensure the parts are all the same.

  • A jig is used to make sure that parts are made exactly the same, without the need for marking out. For example, when drilling through a block of wood with two holes in, it will make sure that the holes are drilled in the same place in each component.
  • A former is used to make sure that parts are shaped or bent to exactly the same shape.
  • A template is something that you can draw around to mark a shape onto material, so that it can be cut or shaped.
  • A pattern is used to make a mould when casting in metal or plastic resin. It is a replica of the finished object and may be made in wood or another soft material. Patterns are also used when shaping plastics in a vacuum-forming machine.
  • A mould is a hollow shape used when casting metal or plastic resin. Moulds for casting metal can be made in a special type of sand, in metal or in plaster. Moulds for casting resin can be made of plaster or rubber.

Shaping by wasting

Shaping by wasting means cutting away material to leave the desired shape. It gets its name because the material which is removed is usually thrown away. Shaping by wasting can be done on any type of material.

Shaping by wasting which can be done by hand

ProcessWoodMetalPlastics
Cutting straight linesTenon saw (dovetail saw for fine work)Hacksaw (junior hacksaw for small work)Hacksaw (junior hacksaw for small work)
Cutting curved linesCoping saw (fret saw for fine work)Abra saw (piercing saw for fine work). Tin snips can be used on thin sheet metalAbra saw (piercing saw for fine work). A coping saw can also be used
Trimming cut edges to a straight lineJack plane or smoothing planeFlat or hand fileFlat or hand file
Trimming cut edges to a curved lineSpokeshave or raspRound or half round fileRound or half round file
Cutting grooves and slotsTenon saw to cut sides, then wood chisel or coping sawDrill holes at ends, then use abra sawDrill holes at ends, then use abra saw or piercing saw

Machine wasting

Cutting timber on a circular saw bench

Almost any wasting technique can be mechanised.

Common machines used for shaping by wasting

ProcessWoodMetalPlastics
Cutting curved linesJig saw, either fixed or portable, with suitable blade. Band saw (teachers only)Bench mounted Jig saw (with suitable blade). Band saw (teachers only)Jig saw, either fixed or portable, with suitable blade. Band saw (teachers only)
Making holesDrilling machine and suitable drill bitsDrilling machine and twist drillsDrilling machine and twist drills
Creating round shapes of different diametersWood turning latheMetal turning latheMetal turning lathe
Cutting grooves and slotsHand router or Computer Numerical Control (CNC) milling machineVertical milling machine or CNC milling machineVertical milling machine or CNC milling machine

CAM and wasting

Shaping machines may also be controlled by computers – an example of CAM. Computer control allows the work to be completed more accurately. The task can be repeated more frequently and quickly without any deviation from the standard.

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