INDIRECT EXTRUSION PDF DOWNLOAD
INDIRECT EXTRUSION PDF DOWNLOAD!
Extrusion process in which a hollow die is pushed through a pressure chamber toward an ingot which is pushed back through the center of the die into a solid. Jump to Hydrostatic extrusion - In the hydrostatic extrusion process the billet is completely surrounded by a pressurized liquid, except where the billet. Extrusion process. - Direct extrusion. - Indirect extrusion. - Impact extrusion. • Extrusion analysis. • Bar drawing. • Wire drawing. • Drawing analysis. Dr. M. Medraj.
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Extrusion - Wikipedia
The die is held in place by a "stem" which has to be longer than the indirect extrusion length. The maximum length of the extrusion is ultimately dictated by indirect extrusion column strength of the stem.
Because the billet moves with the container the frictional forces are eliminated.
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This leads to the following indirect extrusion These defects ruin the piece if it needs to be anodized or the indirect extrusion are important. In order to get around this the billets may be wire brushed, machined or chemically cleaned before being used.
This process isn't as versatile as direct extrusions because the cross-sectional area is limited by the maximum size of the stem. Hydrostatic extrusion[ edit ] In the hydrostatic extrusion process the billet is completely surrounded by a pressurized liquid, except where the billet contacts the die.
This process can be done hot, warm, or cold, however the temperature indirect extrusion limited by the stability of the fluid used. The process must be carried out in a sealed cylinder to contain the hydrostatic medium.
Mechanical engineering: Indirect extrusion
The fluid can be pressurized two ways: A ram or plunger is used to pressurize the fluid inside the container. A pump is used, possibly with a pressure intensifierindirect extrusion pressurize the fluid, which is then pumped to the container. The advantages of this process include: This ultimately allows for faster speeds, higher reduction ratios, and lower billet temperatures.
Usually the ductility of the material increases when high pressures are applied. An even flow of material.
Large billets and large cross-sections can be extruded. No billet residue is left on the container walls.
What is Direct and Indirect Extrusion?
indirect extrusion This is needed to form a seal at the beginning of the cycle. Usually the entire billet needs to be machined to remove any surface defects.
Containing the fluid under high pressures can be difficult. A billet remnant or a plug of a tougher material must be left at the end of the extrusion to prevent a sudden release of the extrusion fluid. Drives[ edit ] Most modern direct or indirect extrusion extrusion presses are hydraulically driven, but there are some small mechanical presses still used.
Of the hydraulic presses there are two types: Direct-drive oil presses are the most common because they are reliable and robust.
Difference Between Direct and Indirect Extrusion Process - WFM
They can deliver indirect extrusion 35 MPa psi. They supply a constant pressure throughout the whole billet. In this process the Ram of the machinery moves and forces the Billet semi-finished metal form through the die. It is the most common Extrusion process used.
The disadvantage of direct extrusion is that the force required indirect extrusion release the billet out of the extruder is more than that required in Indirect Extrusion.