What is extrusion process? Would you like to learn all about this process like extrusion definition, meaning, all types, working principle, advanatges, disadvantages, application, etc.?
Let’s get in!
Let’s learn about the basics of the extrusion process as well as definition and meaning.
There are lots of metal forming processes available under the forming name. One of them is the extrusion.
This one is a widely used process that has different types.
We see different kinds of materials which have different sizes, different shapes, and if we need to change the size or thickness, what we do?
Basically, in the extrusion process, the metal or the workpiece is forced to flow through the die so the cross-section will reduce and the desired shape will be produced or achieved.
Before going to the extrusion definition, let’s try to understand extrusion meaning.
The extrusion process can be done with a material that is hot or cold. It may be continuous long material or semi-continuous thereby producing lots of pieces.
The extrusion process was first patented by the Joseph Bramah that was used to make pipe out of soft metals. The process involved pre-heating the metal and then forcing the metal through a die by using hand driven plunger.
Let’s say if you need to know what exactly is the extrusion process in some lines.
The extrusion is a type of metal forming operation in which the dies with the help of external forces change the shape of the metal piece. The force which the external force applies is compressive in nature.
The extrusion process is classified into various categories. We will check each of the categories of the extrusion process.
So, make sure don’t miss reading the below methods to know more and have a better idea about the extrusion processes.
Before knowing the extrusion process like hot, cold extrusion, etc. you should know what is the recrystallization temperature.
What do you mean by recrystallization temperature?
So, when you heat the metal to certain temperatures the grains of a crystal structure will get a new structure or new crystal shape.
The formation of new grains will start at this temperature.
Another definition can be stated as, Recrystallization is a process by which deformed grains are replaced by a new set of defect-free grains that nucleate and grow until the original grains have been entirely consumed.
Though the different processes of extrusion are different the basic principle is the same.
The required amount of force is given by the plunger or piston.
Extrusion process is clasified based temperature, directions.
Based on temperature, extrusion is divided into two categories,
Based on the temperature, extrusion process is further classified into two categories,
In addition to above, there are also few categories for extrusion process, like,
Let’s get the basic details of all types of the extrusion processes.
What is Hot Extrusion?
You may have assumed something in your mind after reading the name of this process. Well, its pretty simple actually.
Mostly the hot extrusion processes are carried out using the hydraulic presses with pressure of 30-700 MPa. The hot extrusion temperature is different from metal to metal.
Like, Magnesium has 450-450 degree Celsius, Aluminium has 350–500-degree Celsius temperatures.
This process is economical when the production is large that is mass production is necessary.
Some common materials used in the hot extrusion process are,
Advantages of hot extrusion
Disadvantages of hot extrusion
The cold extrusion is different from hot extrusion in the temperature maintaining parameter.
The materials which are cold extruded are,
Advantages of Cold extrusion
Disadvantages of hot extrusion
We have learned the basic concept of hot and cold extrusion process, let see the differences at a glance,
|Hot Extrusion Process||Cold Extrusion Process|
|Scale formation happens on the surface and the surface finish is less||Scale formation doesn’t happen on the surface and the surface finish is better than the hot extrusion process|
|Maintain above recrystallization temperature||Maintain room temperature or below recrystallization temperature,|
|The requirements of force at ram is low as the metal is hot||The requirements of force at ram is high as metal is cold|
|No strain hardening in this process||Strain hardening occurs in this process|
This process consists of a die, ram and billet (work material) and a container.
Advantages of direct extrusion
Disadvantages of indirect extrusion
As we have seen in the forward extrusion the ram, billet moves in the same direction as the material being extruded. But in this process the direction of movement of ram and the extruded component is opposite.
Advantages of backward extrusion
Disadvantages of indirect extrusion
The hydrostatic extrusion is kind of different from the other processes. In this process, the fluid is used to pressurize the billet.
So, this one works on the hydraulic principle.
For the operation to be smooth the shape of the billet is made conical so that it will easily pass through the die.
Now, when we start the machine the ram will exert pressure on a fluid and the pressure will be transferred to billet. It will come out to other side of the die and gets the shape.
Advantages of Hydrostatic extrusion
Disadvantages of Hydrostatic extrusion
In this process a thin-walled copper or aluminium tubes are produced.
In this process, the billet is placed in the container and a punch has exerted the force into the cup and makes a long cylindrical shaped product with reduced thickness.
The impact extrusion is kind of similar to the in-direct extrusion process. It’s the part of cold extrusion process.
It is limited to softer materials like,
In the process, the punch is pushed down at a high speed and with extreme force on the slud to extrudes backward.
The process is generally completed at the cold extrusion like room temperatures.
Popular products like cups, toothpaste cover,s or hollow sections are popular with the impact extrusion process.
Advantages of Impact extrusion
Disadvantages of Impact extrusion
Now we have seen the advantages and disadvantages of and some info about each process from the extrusion.
Now let’s check out overall advantages and disadvantages and applications of the extrusion process.
The advantages of the extrusion process are as follows,
The disadvantages of the extrusion process are as follows,
The application of the extrusion process is as follows,
The common defects of the extrusion process, are as follows,
|1||Cracking on the surface may come due to high friction or when the extrusion temperature is very high or even in case of high ram speed.||Flow pattern should be controlled, temperature as well as friction also should be controlled.|
|2||Piping defects may occur if impurities are present.||Machining or Cleaning the surface.|
|3||Internal cracking may be created due to velocity difference as well as tensile stresses at centre.||It can be cured by using proper die angle and proper extrusion ratio.|
Hence, we have a basic idea about extrusion definition, meaning, all types, working principles, advantages, disadvantages along with application.
Thank you, happy reading!
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