Metal Processing: Preparation, Types, and Shaping Techniques

Preparation of Metals

Metals are materials obtained from minerals in rocks, extracted from open-pit or underground mines.

The deposit is rich in metal ore (the useful part) and other minerals and rocks (gangue or waste rock).

• Metallurgy: The set of industries responsible for the extraction and processing of metal ores.
• Steelmaking (Siderurgy): The metallurgical industry working with ferrous materials, ranging from the extraction of iron ore to its commercialization for manufacturing products.

Types of Metals

• Ferrous metals: The main component is iron (e.g., pure iron, steel, cast iron).
• Non-ferrous metals: Metallic materials that contain no iron or very little iron (e.g., copper, bronze, brass, zinc).

Ferrous Metals

They are currently the most commonly used metals.

An alloy is a mixture of two or more chemical elements, of which at least one (the one in the greatest proportion) is a metal.

• Pure iron: Carbon concentration of 0.008% - 0.03%
• Steel: Carbon concentration of 0.03% - 1.76%
• Cast iron (Casting): Carbon concentration of 1.76% - 6.67%

Non-Ferrous Metals

• Heavy metals: Copper, brass, bronze, nickel, cupronickel, lead, tin, zinc.
• Light and ultra-light metals: Aluminum, titanium, magnesium.

Metal Shaping Techniques

• Plastic Deformation (Warping): Includes all techniques that modify the shape of a metal part by applying external forces.
  • Lamination: The metal is passed through rollers which compress it, reducing its thickness and increasing its length.
  • Extrusion: Passing hot metal through a die or hole of the desired shape by applying force through a piston.
  • Forging: Shaping metal using localized compressive forces.
  • Stamping: Introducing a hot piece of metal between two dies (one fixed and one mobile) to achieve the desired shape.
  • Drawing (Deep Drawing): Hitting or pressing a metal plate to fit a mold or die to the desired shape.
  • Bending and drawing: Shaping sheets along a straight axis.
• Powder Metallurgy:

  Consists of the following steps:

  1. Grind the metal until it becomes powder.
  2. Press with steel dies.
  3. Heat in an oven to 70% of the metal's melting point.
  4. Compress to a suitable size.
  5. Cool.
• Molding (Casting):

  Steps:

  1. Heat the metal until it melts.
  2. Pour the liquid metal into a mold.
  3. Let it cool until it sets.
  4. Remove the part from the mold.

Metal Manipulation Techniques

• To mark (dial): Dividers, scriber, and marking gauge (gramete).
• To cut: Cutter, hacksaw, circular saw, tin snips or shears, press or die, grinder.
• To drill: Punch, drill.
• To carve / cut: Chisel, lathe.
• For polishing / refining: File (lima), sander, grinder, scraper.