What causes formation of the dead metal zone?
In the corner of the leading end of the billet, a separate metal zone (known as the dead metal zone) is formed between the die face and the container wall. Flow pattern B is obtained in homogeneous materials when there is friction at both die and container interfaces, resulting in an extended dead metal zone.
What is a dead metal zone?
The metal at the center of the billet moves faster than the metal at the periphery. In the corner of the leading end of the billet, a separate metal zone is formed between the die face and the container wall, known as a dead-metal zone.
In which extrusion process the direction of flow of metal is in same direction as that of RAM?
Direction extrusion
4. In which extrusion process the direction of flow of metal is in same direction as that of ram? Explanation: Direction extrusion is a process in which the metal billet, placed in a container is forced by a ram to pass through a die. In this type, the direction of flow of metals is, in same as that of movement of ram.
What are the different defects associated with forging rolling wire drawing and extrusion?
Different types of forging defects, Causes and their remedies
- 1.1 Unfilled section:
- 1.2 Cold shut:
- 1.3 Scale pits:
- 1.4 Die shift:
- 1.5 Flakes:
- 1.6 Improper grain growth:
- 1.7 Surface cracking:
- 1.8 Residual stresses in forging:
Why does the force increase even the billet length is decreasing?
Because of this the greatest force required is at the beginning of process and slowly decreases as the billet is used up. At the end of the billet the force greatly increases because the billet is thin and the material must flow radially to exit the die.
What is extrusion process?
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Commonly extruded materials include metals, polymers, ceramics, concrete, modelling clay, and foodstuffs. Products of extrusion are generally called extrudates.
What is extrusion ratio?
The extrusion ratio is the ratio of the area of the work billets cross section (Ao) to that of the extrusion’s cross section (Af). The extrusion ratio, or reduction ratio, can be expressed as (Ao/Af). There is a general rule that if an alloy has higher mechanical properties the extrusion rate needs to be lower.
Which material is not used in extrusion?
Explanation: Extrusion process is not suitable for any of the iron alloys, neither is it suitable for iron metal. For extruding stainless steel or other non-ferrous alloys or steel alloys, extrusion process can be used.
Which of the following process can be used for manufacturing metal forming dies?
Explanation: Extrusion process is a type of metal forming process, in which the material is forced or squeezed out through a hole called die. This process is very similar to squeezing out the toothpaste from the tube.
What are rolling defects?
One of the most common rolling defects is the occurrence of fibers at the edge, which are longer than those at the center. This occurs when concave rolls bend leading to elastic deformations. Thickness at the center implies that the edges are more elongated.
Why is extrusion used?
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. It also creates excellent surface finish and gives considerable freedom of form in the design process.