What is forward extrusion process?
Direct extrusion, also known as forward extrusion, is the most common extrusion process. It works by placing the billet in a heavy walled container. The billet is pushed through the die by a ram or screw. There is a reusable dummy block between the ram and the billet to keep them separated.
Which is the backward extrusion process?
Indirect or backward extrusion is a type of metal extrusion process wherein the billet(work-piece) is kept inside the chamber, which is completely closed on one side. In this type of extrusion, the billet and the container move simultaneously whereas the die remains stationery.
What is the difference between direct extrusion and indirect extrusion?
In the direct process, as described above, the die is stationary and the press ram applies pressure on to the billet. In the indirect method, the ram carries the die and applies pressure on to the stationary billet, in the opposite direction of extrusion.
What is indirect extrusion?
Indirect Extrusion. Indirect extrusion is also called backwards extrusion and in this process, the die is constant whereas the billet & container move together. To keep the die stationary, a “stem” is used which must be longer than the length of container.
What is extrusion and its types?
Extrusion is a manufacturing process that involves forcing base metal through a pre-shaped die to create objects with a specific shape and profile. There are different types of extrusion processes, however, including cold, hot, friction and micro.
Which plunger is used in indirect extrusion?
Backward or Indirect extrusion: In this type of extrusion process, a hollow plunger is used.
What are the types of extrusion?
Types of Extrusion Process
- Direct Extrusion.
- Indirect Extrusion.
- Hydrostatic Extrusion.
- Lateral or Vertical Extrusion.
- Hot extrusion.
- Cold Extrusion.
- Impact Extrusion.
What are the main extrusion defects?
The common defects in extrusion process are: Improper System Engineering/Installation, Improper Operation, Resin Defects, Improper Materials Addition, Surging, Poor mixing, Melt toughness or fracture, Overheating, Moisture release, Trapped air, Contamination.
Whats the opposite of extrusion?
extrude. Antonyms: intrude, insert, introduce. Synonyms: thrust out, eject, expel.
Which is true of the forward extrusion process?
In the forward extrusion process the flow of material and ram movement Were both in the same direction. The following table compares the forwards (direct) and backwards (Indirect extrusion process).
What’s the difference between direct and indirect extrusion?
The following table compares the forwards (direct) and backwards (Indirect extrusion process). This process is also known as extrusion down method. It is used for producing small thin walled seamless tubes of aluminium and copper. This is done in two stages.
Why is a dummy block used in forward extrusion?
It is known as forward extrusion because the billet and the ram are moving forward in the same direction. A dummy block is placed between the ram and the billet in order to prevent them from touching. There is one major drawback to this method, which is the amount of force required to force the billet through the die.
How is the extrusion of a ram called?
As the ram presses backwards, the material has to flow forwards through the opening in the die. The ram is made hollow so that the bar of extruded metal may pass through it unhindered. This process is called backward extrusion process as the flow of material is in a direction opposite to the movement of the ram.