Assembly Line

Forging

Hammers or presses squeeze hot metal into shape. The metal's grain follows the part's outline, which makes it tough.

24 lines that use it

Air conditioner 6 stations · 23 raw sources Airliner 9 stations · 33 raw sources Ball bearing 9 stations · 13 raw sources Blender 7 stations · 30 raw sources Bolt 6 stations · 13 raw sources Bronze 5 stations · 6 raw sources Drill bit 7 stations · 15 raw sources Drum kit 8 stations · 19 raw sources Fire extinguisher 8 stations · 27 raw sources Gas cylinder 10 stations · 25 raw sources Hammer 8 stations · 21 raw sources Hip implant 9 stations · 22 raw sources Jet engine 7 stations · 23 raw sources Locomotive 8 stations · 28 raw sources Nail 6 stations · 14 raw sources Nichrome 8 stations · 15 raw sources Scissors 8 stations · 22 raw sources Screw 7 stations · 13 raw sources Sewing needle 8 stations · 16 raw sources Spark plug 8 stations · 16 raw sources Stainless steel water bottle 7 stations · 25 raw sources Steel pipe 7 stations · 13 raw sources Titanium 5 stations · 9 raw sources Wrench 9 stations · 20 raw sources

What it looks like on the line

  • HammerForge in dies. One die is fixed and the other drives down on a piston, often in stages with several shapes. Forging keeps the steel's grain unbroken, which helps a part that takes repeated blows.
  • Steel pipePierce a billet instead. For weld-free pipe, a solid billet is heated and drawn over a piercing rod in a process called rotary piercing, which opens a hole down its center with no welding.
  • Ball bearingHead balls from wire. A heading machine slams two hemispherical dies onto a slug of wire with no added heat. The result is a rough ball with a ring of excess metal, called flash, around its middle.
  • Jet engineForge the fan and compressor blades. Titanium is pressed hot into blade shapes that must withstand centrifugal pull and the impact of air at speed. The blades are then machined and polished.
  • WrenchCut and heat the billet. Long rods of 6140 chrome vanadium steel are cut to size and often sand-blasted clean. Each billet then goes into a furnace until it is hot enough to flow.
  • WrenchDrop-forge the shape. A drop hammer pounds the billet into closed dies, giving head and handle in one piece. The result is a rough forging with the right shape but not yet the right dimensions.
  • AirlinerForge the landing gear. Heavy steel and titanium forgings take the shock of landing, then are machined to final shape and finished.
  • TitaniumForge into mill products. The ingot is turned into billet, bar, plate, sheet, strip and tube. Heating titanium in air during forging can leave a brittle, oxygen-rich skin, so shops take care with the atmosphere.
  • Spark plugForm the steel shell. Raw steel is pressed repeatedly into dies until it reaches the final hex-topped shape.
  • Hip implantForge near final shape. A cobalt-chromium or titanium body is pressed in forging dies to a shape only slightly bigger than the finished part. Near-net forging means little metal has to be cut away later, though stems can also be cast or milled.
  • ScrewUpset the head. Punches squeeze one end of each blank into a head at room temperature. A cold heading machine can turn out hundreds of parts a minute, and the grain of the steel flows around the head instead of being severed.
  • BronzeHammer or roll sheet. For sheet, a softer bronze with only about 6 percent tin is cast into ingots and hammered flat. Bronze Age helmets and armor were made this way, while blades were cast from the harder bronze with about 10 percent tin.