Metals

Metals

1. - Shaping techniques

   • 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.
   • Extrusion: The heated metal is pushed through a hole by a piston, using compression.
   • 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 Manual forging has been replaced by industrial or mechanical forging.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.
   • 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.
   • Punching: This is a cold forging process: a sheet of metal is hit with a punch to make the required shape in a mould.
   • Bending: A metal sheet is subjected to force to make a curved shape with a specific curve radius.
   • 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.

2. Oxyacetylene welding: An oxyacetylene blowtorch is used which can reach temperatures of over 3000°C.

3. Soft soldering: We use a tin-lead alloy. This is heated with an electric soldering iron, which reaches temperatures of 400°C.

4. Hard soldering: Brass or copper is heated with a blowtorch to a temperature of 800°C.

5. Polishing: This technique produces a shine, using a polishing wheel with revolving, abrasive wheels or strips.

6. Grinding: A grinder is used to refine surfaces to precise, accurate dimensions and to remove any imperfections. We can use it on flat pieces or cylinders.

7. Lapping: A lapping machine has a vertical handle and abrasive discs. This is usually used for finishing openings and conical surfaces, and is very accurate.

8. Buffing: This technique also produces a shine. A mechanical buffing wheel is used with a steel disc or roll, which can be abrasive.

9. Coating: This technique is used to protect the metal. The metal is coated in plastic or other metals, e.g. zinc, silver, gold, nickel or chrome. This technique is called galvanisation. Paints, varnishes and enamels can also be used.

10. Drilling: You have to do gaps on the material.

11. Marking: Centre punch and scriber The centre punch is used to mark lines and the scriber to mark points on sheets of metal.

12. Cutting: You have to take tools that can cut the material that you are working with.

13. Shaping: It works by turning the object while a blade moves along the length of the object removing the metal.

14. Powers tools for cleaning: -Sander -Grinder

15. Cleaning: It's used to shave small fragments.