Manufacturing Process-I

Subject Teacher : Dr Tariqure Bhatti

Quaid-e-Awam University College of Engineering, Science and Technology, Larkano.

Batch: 14-ME3rd year, 2nd term

Members:

Muhammad Awais 14ME08Arsalan Hussain 14ME09Atique Ahmed 14ME10

Extrusion Direct and Indirect Extrusion Hot Extrusion Cold Extrusion Applications of Hot and Cold extrusion Advantages And disadvantages of Hot and cold

extrusion

Topics

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Extrusion is the process by which a block/billet of metal is reduced in cross section by forcing it to flow through a die under high pressure.

What is Extrusion

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What is Extrusion

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The process begins by heating the stock material. It is then loaded into the container in the press.

A dummy block is placed behind it where the ram then presses on the material to push it out of the die.

Extrusion Process

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Afterwards the extrusion is stretched in order to straighten it. If better properties are required then it may be heat treated or cold worked.

The extrusion process is generally economical when producing between several pounds and many tons, depending on the material being extruded.

Extrusion Process

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According To Direction: Direct & Indirect Extrusion

By Equipment: Horizontal and Vertical Extrusion

By Operating Temperatures : Hot And Cold Extrusion

Classification of Extrusion Processes

15- 50 MN capacity or upto 140 MN)

• Used for most commercial extrusion of bars and shapes.

3 to 20 MN capacity

Typical parts produced by extrusion are trim parts used in automotiveand construction applications, window frame members, railings, aircraftstructural parts .

•Hot extrusion is done at an elevated temperature to keep the material from work hardening and to make it easier to push the material through the die.

•Most hot extrusions are done on horizontal hydraulic presses that range from 250 to 12,000 tons.

•The biggest disadvantage of this process is its cost for machinery and its upkeep.

•Typical parts produced by extrusions are trim parts used in automotive and construction applications, window frame members, railings, aircraft structural parts.

•Hot extrusion is done at fairly high temperatures,approximately 50 to 75 % of the melting point of themetal.

• The pressures can range from 35-700 Mpa.

•The most commonly used extrusion process is the hot direct process. The cross-sectional shape of the extrusion is defined by the shape of the die.

•Due to the high temperatures and pressures and itsdetrimental effect on the die life as well as othercomponents, good lubrication is necessary.

•Oil and graphite work at lower temperatures, whereas at highertemperatures glass powder is used.

•Complex Solid or hollow shapes can be produced.

•Small Quantities can be economically produced.

• Delivery times are often far shorter than alternative processes.

•High equipment set up maintenance cost.

•Extrusion process for metals is at very high temperatures.

•Die is Preheated to increase it’s life so there are chances of oxidation of hot billet.

•Process wastage is higher as compared to rolling.

•The process of cold extrusion is carried out at room temperature or at marginally elevated temperature, with the assistance of Extruder and Extrusion Machines. These equipment / machines are specially developed on the basis of innovative Extrusion Technology.

• Cold extrusion can also be defined as the process of shaping of a cold metal by striking a slug.

•This striking is done with a punch (in closed cavity), which forces the metal in upward direction around the punch.

• This process is also called Cold Forging, Cold Pressing, Extrusion Pressing, and Impact Extrusion.

Cold extrusion is also defined as a compressive forming process (push-through), where the starting material is billet / slug and the process is carried out at the room temperature.

•During the cold extrusion process, deformation heating of the deforming material takes place at several hundred degrees.

•Deformation heating is the process of conversion of deformation work to heat. In general, a punch is used for applying pressure to the enclosed billet in the stationary die.

•The cold extrusion process is widely used to manufacture products from Copper, Lead, Tin, Aluminum Alloys, Titanium, Molybdenum, Vanadium, Steel, Zirconium, and Niobium.

•Some of the products that are developed using this process include various parts such as Collapsible Tubes, Gear Blanks, Aluminum Cans, Cylinders, Fire Extinguisher Cases, Shock Absorber Cylinders, and Automotive Pistons.

Cold Extrusion is also used in the Automobile Sector, in various applications such as:

•Injection technology

•Engine control

•Fuel supply

•Automatic transmissions

•Seat technology

•Safety systems (restraint systems)

Cold extrusion is highly advantageous as it is used to withstand all the stresses that are created by the extrusion process.

There are various advantages of cold extrusion over the hot extrusion, some of the important ones are listed below:

•No oxidation process.

• Higher strength due to cold working Good mechanical properties that are provided the temperatures created, are below the re-crystallization temperature.

•Closer tolerances

•Good surface finish

•Fast extrusion speeds, in case the material is subjected to hot shortness

•Dimensional precision

•Net-shaped features

•Lower energy consumption

• Higher production rates

•Clearance Work Environement

Apart from the above-mentioned advantages, there are some disadvantages as well that are associated with cold extrusion. These are lubrication cost, higher loads, limited shape complexity, and limited deformation

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