1239
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1239 Presentation Transcript

  • 1. PRESENTED BY Nilesh Mahatmaji Dudhabhate
  • 2. Extrusion is the process of confining the metal in the closed cavity and then allowing it to flow from only one opening so that the metal takes the shape of the opening. Extrusion is a process used to create objects of a fixed, cross-sectional profile.  A material is pushed or drawn through a die of the desired cross-section. The long straight metal parts of solid ,round ,T-shaped , L-shaped cross- sectional products can be manufactured.
  • 3. The extrusion process is often likened to the squeezing of tooth paste from a tube, as is illustrated : The top of the tube represents the die and determines the shape of the extrusion, while the paste may be considered to be the billet.
  • 4. In general, extrusion process is used to produce long part of same cross-section.
  • 5. Billet:- The billet is the starting stock for the extrusion operation.Extrusion billets may be a solid or hollow form, commonly cylindrical, and is the length charged into the extrusion press container. Extrusion operations typically take place with billet heated. However during the extrusion, the billet is still solid.
  • 6.  Dies are the cutting tools used in the extrusion processes. (a) (b) (c)
  • 7.  Direct Extrusion  Indirect Extrusion  Impact Extrusion  Hydrostatic Extrusion
  • 8. Also called as forward extrusion process.  The flow of metal in the forward direction that is same as that of direction of ram/plunger. Hot metal billet is loaded in cylinder. The plunger compresses metal billet against the die and forces it to flow through die opening and produces extruded product Extruded product acquires the shape of opening.
  • 9. . In this process, the problem of friction is more because of relative motion between the heated metal billet and the cylinder walls.
  • 10. Also called as indirect extrusion process. In order to completely overcome the friction, the backward extrusion process I used. The hot metal billet is confined fully by the cylinder. The ram which have die, compresses the metal against the container, forcing it to flow backward through the die opening in the hollow plunger or ram.
  • 11. It is termed as backward because of the opposite direction of the flow of metal to that of ram movement. The billet in the container remains stationary and hence no friction. Indirect extrusion does not requires as much force as direct extrusion.
  • 12. Impact extrusion is a manufacturing process similar to extrusion and drawing by which products are made with a metal blank. The blank is pressed at a high velocity with extreme force into a die/mold by a punch.
  • 13. In the hydrostatic extrusion process the billet is completely surrounded by a pressurized liquid, except where the billet contacts the die.
  • 14. Disadvantages:- Containing the fluid under high pressures can be difficult. Limited use due to complex tooling, high pressures, special equipment, and long cycle times. Advantages:- No friction between the container and the billet reduces force requirements. 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. Large billets and large cross-sections can be extruded.
  • 15. Extrusion often minimizes the need for secondary machining,and as a result could result in financial savings. However extruded objects are not of the same dimensional accuracy or surface finish as machined parts.