What is indirect extrusion?
Indirect Extrusion is a method in which the Ram is stationary and the dye moves forcing the Billet through the dye. So as to keep the die stationary a stem is used which should be longer than the container containing the Billet.
How does indirect extrusion work?
In the indirect method, the ram carries the die and applies pressure on to the stationary billet, in the opposite direction of extrusion. As such, there is no billet to container friction influence, and the force during extrusion remains relatively constant from the front of the extrusion to the rear.
What are the difference between direct extrusion and indirect extrusion?
The direct extrusion press pushes the billet through a fixed container and die via the press ram. On the other hand, in the indirect extrusion process the billet is fixed while the die is pushed into the container holding the billet.
Which of the flow pattern is found in indirect extrusion?
Flow pattern A is obtained in extrusion of homogeneous materials in the presence of friction at the die interface, not at the container-billet in- terface. This flow pattern is good for indirect extrusion. The metal at the center of the billet moves faster than the metal at the periphery.
Which plunger is used in indirect extrusion?
Backward or Indirect extrusion: In this type of extrusion process, a hollow plunger is used.
What is direct extrusion used for?
6.1. 2 Extrusion. Extrusion is a forming process used to create products with a constant cross-section such as pipes, bricks, profiles, etc. It is very common in the field of ceramics, metal processing, food industry, and plastic materials, just to mention the most important.
What is direct 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.
What is the difference between forward and backward extrusion?
Backward or indirect extrusion is used to make hollow shapes, because the punch is solid and thrusts the material around itself into the space between itself and the die. The other sort of impact extrusion, forward (or direct) extrusion, can only produce solid sections.
What is a dead zone in extrusion?
In the process of direct extrusion through a single-hole flat die we observe dead zones described by the so-called angle of the dead zone. The value of the dead zone depends on the friction between the billet and the container, the extrusion ratio and the geometry of the container.
What is extruder in polymer processing?
Extrusion is a process of manufacturing long products of constant cross-section (rods, sheets, pipes, films, wire insulation coating) forcing soften polymer through a die with an opening. Polymer material in form of pellets is fed into an extruder through a hopper.