Extrusion is a process that involves pushing material through a die with a desired cross-section to create objects with a fixed cross-sectional profile. Its two main advantages over other manufacturing processes are its ability to create very complex cross. Sections and its ability to work with brittle materials because the material only experiences compressive and shear stresses.
Well, in this reading, I’ll be exploring what extrusion is, diagram, its characteristics, types, advantages, and disadvantages, how it’s work.
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Contents
What is Extrusion?
Extrusion is a manufacturing process to create a specific shaped object by pushing a material through a die. The die is a little disk with an opening of a specific size and shape. When the material is put under pressure through the die, it will create a desired shape. Often the die is made of steel.
The method of extrusion is used to produce metal, when a metal or work piece is pushed through a die to reduce its cross section or take on the desired shape. The manufacture of steel rods and pipes makes great use of this method. Compressive force is applied during the extrusion process of the work item.
Diagram Of Extrusion
Characteristics of Extrusion
- Able to produce intricate cross-sections and consistent over the extrudates’ whole length.
- Die design, extrusion ratio, billet temperature, lubrication, and extrusion speed are variables that impact extrusion quality.
- To learn about the five important design factors for metal extrusion and design for manufacture (DFM) extrusion recommendations, check out the comprehensive design reference “How to design parts for direct metal extrusion.”
- It may be done either hot or cold, just like any other metal forming technique, however it’s usually
- done at a higher temperature to lessen the extrusion force and increase the material’s ductility.
- Low cost as a result of high production rate and less waste from raw materials
- Breakable materials can distort without a tear as it only exerts compressive and shear forces in the stock part.
- Parts that are formed have an excellent surface finish which minimizes post-processing machining.
- Metal extrusion tends to produce a favorable elongated grain structure in the direction of the material.
- The minimum wall thickness of ~1mm (aluminum) to ~3mm (steel) could be achieved.
Types of Extrusion
There are several options available for metal extrusion shapes. Even while the fundamental ideas are constant, we employ them in various ways to produce a wide range of goods.
All of the metal extrusion procedures fall into one of the following categories are: hot extrusion, extrusion without heat, extrusion that is heated.
1. Hot Extrusion.
In order to prevent work hardening and facilitate material pushing through the die, hot extrusion, also known as hot working, is carried out above the temperature at which the material recrystallizes. Horizontal hydraulic presses with capacities ranging from 230 to 11,000 metric tons (250 to 12,130 short tons) are used for the majority of hot extrusions.
Because the pressure ranges from 30 to 700 MPa (4,400 to 101,500 psi), lubrication is necessary to be glass powder for extrusions at higher temperatures, or oil or graphite for extrusions at lower temperatures. The primary drawback of this procedure is the expense of the apparatus and its maintenance.
2. Extrusion Without Heat.
Room temperature or about room temperature is used for cold extrusion. The lack of oxidation, increased strength from cold working, tighter tolerances, improved surface polish, and quick extrusion rates in the event that the material is susceptible to hot shortening are the benefits of this versus hot extrusion.
Lead, tin, aluminum, copper, zirconium, titanium, molybdenum, beryllium, vanadium, niobium, and steel are among the materials that are often cold extruded. Shock absorber cylinders, gear blanks, fire extinguisher boxes, and collapsible tubes are a few examples of the goods made using this technology.
3. Extrusion That Is Heated.
Whenever extrusion is done at warm extrusion is the process of using metal at temperatures between ambient temperatures and the metal’s recrystallization temperature. Warm extrusion had advantages over the previously described production procedures, including more control over the ductility and other qualities of the extrudate.
Warm extrusion may be performed from 424°C to 975°C. At no time throughout the metal-forming process does the temperature rise over the critical melting point. #4: Extrusion by friction. The UK’s welding institute is credited with creating friction extrusion, which was patented in 1991.
When it was first developed, the main goal was to create uniform microstructures and particle distributions in metal matrix composite materials. The charge (a billet or other precursor) is friction extrusion spins in relation to the extrusion die, which sets it apart from traditional extrusion. There is an extrusion force used in order to force the charge into the die.
In actual use, the charge or the die may rotate independently or in opposition to one another, the process is significantly impacted by the relative rotating motion of the charge and it will die.
Working Principle
An extrusion press works like a piston cylinder device in which metal is placed in a cylinder and pushed by a piston; the upper portion of the cylinder is fitted with a die.
- Now, a compressive force is applied to this part by a plunger fitted into the press which pushes the billet towards die.
- The die is a small opening of required cross section.
- In extrusion, a piston or plunger is used to apply compressive force at work piece.
- This process can be summarized as follows: first, a billet or ingot (a metal work piece of standard size) is produced; this billet is heated in hot extrusion or remains at room temperature and is placed into an extrusion press.
- The work metal to pass through the die and take on the desired form.
- The extruded portion is now taken out of the press and given a heat treatment to improve its mechanical qualities.
- This is how the extrusion process functions fundamentally.
Advantages of Extrusion
- Rolling cannot provide the benefits of the extrusion technique
- A broad range of part complexity and variety can be produced using extrusion.
- It is possible to get a consistent cross-section of the parts.
- Compared to other methods, the extrusion method is inexpensive.
- It is simple to make items with a broad range of diameters and wall thicknesses using the extrusion method.
- Because the extruded component is very heated after the extrusion process, the post-extrusion works can be completed very quickly.
- To complete the process, the extruder must only be run once.
- Extrusion is a simple process that can be automated.
- An extruded product’s smooth surface, exact measurements, and clearly defined shape all serve as indicators of its quality.
Disadvantages of Extrusion
- The extruded component is extremely hot as a result, and this causes dimension variations after extrusion.
- After extrusion, undesirable residual tensions may remain.
- The manufacturers must accept a substantial degree of deviation from the original part because of this unpredictable expansion.
- The same cross-sections must run the full length of the object.
- Size variations are brought on by hot materials and production.
- Squeezing requires a lot of effort.
- It requires heavier tools.
- High startup or establishment costs.
- Not suitable for small-scale manufacturing.