Manufacturing

Manufacturing

1. Joining processes

   • Welding
     • Fusing two or more parts using heat, pressure, or both
   • Brazing
     • Form, fix, or join by soldering with an alloy of copper and zinc at high temperature.
   • Soldering
     • Used for joining metal parts to form a mechanical or electrical bond
   • Adhesive bonding of materials
     • Joining between two or more parts is accomplished by the solidification or hardening of a non-metallic adhesive material, placed between the faying surfaces of the part

2. Wasting Processes

   • Sawing
     • Saws use sharp teeth to cut away material Hacksaws are used to cut metal Junior hacksaws are used to cut metal and polymers Coping saws are used to cut round shapes in polymers Mechanical hacksaws are used to cut metal bars Bandsaws are used with different blades to cut a wide range of materials and parts
   • Shearing
     • Uses blades that are parallel to each other, but with a small offset between them These apply force to the material Tin snips can cut thin sheets of material Guillotines can make straight cuts in sheet material
   • Drilling
     • Makes holes
   • Filing
     • Files have a pattern of small teeth that cut away material They are used to remove burrs, round edges and to remove small amounts of excess material
   • Threading
     • Internal threads are cut with a tap External threads are cut with a die
   • Routing
     • Routers and mills use a high-speed rotating tool Routers can cut thin material or be used to put a profile on an edge
   • Milling
     • Routers and mills use a high-speed rotating tool Milling is used to make flat surfaces or grooves in metal products
   • Turning
     • Turning makes parts with a round profile It is carried out on a lathe The workpiece is rotated and the tool is moved against it Can end face, parallel turn, centre drill and bore
   • Laser cutting
     • Cuts material by melting, burning or vaporising it around the outline of the required shape A computer controls the movement of the laser Limited to 2D shapes in sheet material Shapes can be nested to minimise waste

3. Shaping processes

   • Sand casting
     • Molten metal is poured into a green (resin-bonded) expendable sand mould
   • Die casting
     • Mould and scrap metal, pewter
   • Injection moulding
     • Materials being injected into moulds, injection moulder, copper, heat up, chamber, nozzle, mould
   • Powder metallurgy

4. Forming processes

   • Forging
     • Used for metal Early examples date back 6000 years! Hand forging (by blacksmiths) was used to make tools, weapons, jewellery and horseshoes A piece of metal is heated until it glowing red then hit with a hammer to shape it An anvil or former may be used to achieve the shape needed The metal may have to be reheated many times until the required shape is achieved
   • Press forming
     • Used for metal sheets, typically up to 3 mm thick A press changes the shape of the sheet by pushing it into a former or mould One hazard is crushing fingers when the press operates – machine guards or push button controls may be used to ensure hands are away from the press Gloves can be used if the sheet material has sharp edges Safety glasses are worn if there is a risk of the product or a machine part breaking
   • Vacuum forming
     • Used with thermoplastic polymer sheets The sheet is clamped over the mould to make an airtight seal The sheet is heated until flexible, then the mould is raised The air is removed from below the sheet The external air pressure pushes the sheet onto the mould As the sheet cools, it hardens into its new shape Excess material is cut away (and can be recycled)
   • Strip heating
     • Used with polymers Makes a simple angle bend in the product The polymer sheet is made into a 2D net of the item The line where the bend is to be made is placed directly over the heat source – typically a heating bar or wire These provide heat due to electrical resistance When the material being bent reaches a suitable temperature, it becomes flexible along the heated line A former can be used to achieve the angle needed
   • Moulding of composite materials
     • Layers of fibre are placed into a mould Either: A mating part to the mould closes and resin is injected. Or: Resin is applied by brush and allowed to soak into the spaces between the fibres Heat and/or pressure may be used to cure the material Excess material from the edges is cut away
   • Industrial forging
     • Often used with steel Blocks of material are compressed into the shape of a cavity The metal is heated to red hot to make it malleable The ram may apply hundreds of tons of pressure Excess material (flash) from where the parts of the cavity meet is cut away The forged product is typically very strong with few surface defects – but may have some anisotropic properties