METALS

Metals can be formed in a wide range of ways:-

Reforming-

Casting

Rolling

Drawing

Forging

Extruding

Sintering

Wasting -

Cutting

Grinding

Also by fabrication - by joining with adhesives, fasteners (nuts and bolts, screws,rivets etc.), welding, soldering (brazing,silver soldering, soft soldering).

Complex shapes can be produced using moulds:-

Metals can be cast into these moulds

Sand casting can be used for a wide range of metals but gives a poor surface finish. (Click on this link to go to sand casting)

Die casting using metal moulds is used for aluminium and zinc based alloys which have a low melting point.

Sintering uses powdered or sintered metals which are compressed inside the mould. The particles fuse together. Heating of the fused mass in a furnace causes grain growth of the metal across the mass, giving much greater strength. Carbide tips are formed by a sintering process.

These casting and moulding processes minimise waste.

Drop forging is another method using moulds and dies with minimal waste.

A hydraulic press (a fly press can be used on a smaller scale) can be used to deform metals using great pressure and dies. Car body panels are pressed in this way. The press will also cut parts out. A body panel will go through a series of pressings on its way to completion.

Some sheet metal parts are simply pressed (stamped out) to cut them out. The iron laminations used in transformers and electric motors are stamped out using a cutting die.

Extrusion of hot metal - through a die is similar to the method used for plastic extrusion but here a hydraulic ram is used rather than a screw.