4. Shaping techniques

4. Shaping techniques

1. SHAPING

   • ROLLING: The unprocessed metal is passed through a series of rollers that compress it, reduce its thickness and increase its length. It's usually done when the metal is hot
   • PRESS FORGING: The heated metal is placed between two dies, one fixed and the other mobile. The dies are the shape of the object we want to make. They are pressed together so that the piece takes the shape of the die.
   • EXTRUSION: The heated metal is pushed through a hole by a piston, using compression.
   • WIRE DRAWING: A wire is pulled through a hole that has the required dimensions. A rotating drum is used to pull it through the hole to increase its length while reducing its diameter.
   • BENDING: A metal sheet is subjected to force to make a curved shape with a specific curve radius.
   • PUNCHING: This is a cold forging process: a sheet of metal is hit with a punch to make the required shape in a mould.
   • FORGING: The metal piece is shaped by repeated and continuous compression forces using hammers, tongs and anvils. Manual forging has been replaced by industrial or mechanical forging. The piece is placed on a platform that acts as an anvil. Using a pneumatic or hydraulic machine, the hammer rises and falls onto the piece again and again. Forging is usually carried out when the piece is hot.

2. CASTING

   • Molten metal is poured into a container with a hollow space inside, which is the shape of the object we want to make. The mould can be made from sand, steel or cast iron. The metal is heated in a furnace. The liquid metal is poured into the mould. It is left to cool down. The piece is removed from the mould. Uses: Engine blocks, fire hydrants, small parts and alloys with low melting points, ornaments, jewellery, sculptures and dental implants.