Forming Methods

Forming Methods

1. Woods

   • Laminating
     • Birch used widely
     • Adhesive applied to each layer of veneer, stacked on top of each other
     • Veneers are clamped, adhesive dries, shape = formed
     • Advantages
       • Produces strong/light products
       • Accomodates a range of thicknesses
       • One off/batch/mass production
       • Combined with other materials
     • Disadvantages
       • Long process
       • Many steps
       • Restricted to bends in single direction
   • Steam Bending
     • Wood steamed and softened
     • Wood can be manipulated when soft
     • Materials
       • Hardwoods more suitable than softwoods
       • Beech/Oak common for furniture
     • Advantages
       • Most effective way to bend wood
       • Good aesthetic appeal
       • Good strength - weight ratio
       • Parts can be individually produced
     • Disadvantages
       • Only good quality hardwoods should be used
       • Not suitable for precise applications

2. Metals

   • Blanking/Piercing
     • Sheet metal aluminium is common
     • Requires punches which use shearing action
     • Adv/Disadv
       • Can produce many shapes
       • Any sheet metal used
       • High level of accuracy
       • Restricted to sheet material
       • Fair amount of wastage
       • Limited to size of stock
   • Press forming/Deep drawing
     • Steel/Copper/Brass/Al
     • Blanks forced through die so takes shape of punch
     • Advantages
       • Increases Stiffness
       • Suitable for high vol. of production
       • Carried out at room temp
     • Disadvantages
       • High cost
       • V. high levels of stresses needed
   • Drop Forging
     • V. Large forces exerted onto metal between die halves
     • Refining process when large numbers of similar objects are required
     • Adv/Disadv
       • Can be v. expensive
       • Produces strong pieces
       • Dangers working with hot metals

3. Plastics

   • Injection Moulding
     • Granules of plastic powder fed into hooper
     • Motor turns thread which pushes granules along to heater section, melts into liquid which is forced into mould
     • Polystyrene/Nylon/Polythene
     • Advantages
       • V. complex shapes produced
       • Consistent qualities
       • Fast process
       • Low labour costs
       • Little waste/Little finishing required
     • Disadvantages
       • High initial set up costs
       • Moulds are expensive
   • Blow moulding
     • Heated granules are injection moulded into pre-formed shape which is positioned into mould. Air forced into mould forces plastic to sides, gives shape of bottle
     • HDPE/LDPE/PP/PVC/PET
     • Advantages
       • Rapid method of producing hollow shapes
       • Low/High production scales
       • Many plastics can be used
       • Less expensive than injec mould
     • Disadvantages
       • Limites to hollow parts
       • Moulds expensive
       • Diffictult to make triangles
   • Thermforming
     • Mold halves press softened plastic into shape
     • ABS/Acrylic/Polystyrene
     • Advantages
       • Low cost process
       • Produces smooth shapes with extra detail produced
     • Disadvantages
       • Plastic sometimes gets too thin
       • Limited to simple designs
       • Trimming required results in waste
   • Vacuum Forming
     • Mould pushed up to a heated plastic sheet
     • Vacuum pumps out all air beneath sheet
     • ABS/Acrylic/Polystyrene
     • Advantages
       • Available to schools
       • Simple/Easy to use
       • Range of materials
       • One off/Large scale production
     • Disadvantages
       • Need to trim excess results in waste
       • Moulds cant have 90 degree angles