Mar 16, 20202 min read

An overview of metals processing methods | Material Properties

Updated: Aug 16, 2020

Materials processing, the series of operations that transforms industrial materials from a raw-material state into finished parts or products.

Historically materials processing by hand is as old as mechanization which began with the Industrial Revolution of the 18th century principally in England.

Since then, metal processing methods, techniques have evolved, processes got faster, higher strengths steel can be achieved as well as different properties can be specified.

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Content of below information:

Casting Processes
Forging Processes
Rolling
Extrusion

1.Casting Processes

The production of a metallic component is by casting of the molten metal into a mould. Most casting processes are used for the production of the initial metal ingot or near-finished shape (eg. I-beam) metals ready for the fabrication procedures.

Sand Casting:

Sand casting is characterized by using sand as the mould material.
Over 60% of all metal castings are produced via a sand casting process
Commonly used for hard but very brittle metals ( mainly for Aluminium Alloys)
Sand casting methods can have a very high quality of the completed product providing accurate dimensions to the finished surface of the metal.

2. Forging ( traditional hammering)

definition: manufacturing process involving the shaping of metals using localised compressive force (manual or mechanical)

Drop-forging: heating a metal and hammering it into a special die to produce a final product.

Hot-pressing: the hammer is replaced by a hydraulic-driven ram. - the metal is gradually squeezed

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3. Rolling

Rolling is the cheapest and most efficient method of reducing the cross-sectional area of a metal section. Commonly used for producing flat products. The rollers are used to shape the product and by rolling, redistribution of any impurities reduce the effect of any segregation present in the original ingot.

Advantages:

Reduction of segregation due to rolling
More homogeneous product
Reduced grain-size

1) Cold Rolling

Applied to very malleable metals and alloys.

Due to rolling the metal crystals are distorted becoming hardened therefore internal stresses increase, increasing the strength of the metal.

2)Hot Rolling

The temperature of hot rolling is high, making the metal more malleable and allowing metals to deform easier.

Hot rolling is carried out well beyond recrystallisation temperature. These high white-hot temperatures mean that crystallisation happens instantly as the metal passes through the rollers speeding up the process of shaping metals.

4. Extrusion

Used to shape a variety of metals to a desired complex fixed cross-sectional dimensions.

Aluminium extrusion is widely used in construction, automobile and aircraft manufacture, industrial machinery and consumer goods.

Temperatures: 350-500 celsius for aluminium alloys

A ram is driven with pressure to force the metal through a hard steel mould. The process of extrusion could be characterised to be the same manner to the flow of toothpaste from its tube.