Extrusion & its types PPT
- 2. Metal Extrusion is a metal forming manufacturing process in which a cylindrical billet inside a closed cavity is forced to flow through a die of the desired cross-section. These fixed cross- sectional profile extruded parts are called “Extrudates” and pushed out using either a mechanical or hydraulic press. The process which was first patented by Joseph Bramah was first used to extrude lead pipes by Thomas Burr. What is MetalExtrusion?
- 3. Characteristics of metal extrusion Able to create complex cross-sections and will be uniform over the entire length of the extrudates. Factors that affect the quality of extrusion are die design, extrusion ratio, billet temperature, lubrication, and extrusion speed. Similar to any other metal forming process, it can be performed either hot or cold, although the process generally is carried out at elevated temperatures in order to reduce the extrusion force and improve the ductility of the material Low cost due to reduced raw material wastage and high production rate
- 4. Brittle material can be deformed without a tear as it only exerts compressive and shear forces in the stock part Parts that are formed have an excellent surface finish which minimizes post-processing machining The minimum wall thickness of ~1mm (aluminium) to ~3mm (steel) could be achieved Metal extrusion tends to produce a favourable elongated grain structure in the direction of the material.
- 5. Types of the metal extrusion process Metalllextrusiiion can be subdiiiviiidedand grouped iiintothe follllllowiiing categoriiies dependiiing on the diiirectiiionof extrusiiion flllow,,,the mediiium used to applllyforce,,,workiiingtemperature,,, etc. DiiirectExtrusiiion Indiiirect Extrusiiion Hydrostatiiic Extrusiiion Lateralll or VertiiicalllExtrusiiion Hot extrusiiion CollldExtrusiiion Impact Extrusiiion
- 7. Indirect Extrusion In Indirect Extrusion, the die is located at the end of the hydraulic ram and moves towards the billet inside the cavity to push the material through the die. This process consumes less power due to the static billet container causing less friction on the billet. However, supporting the extruded part is difficult when the extrudate exits the die.
- 9. Hydrostatic extrusion In hydrostatic extrusion, the chamber/ cavity is made smaller than the billet and filled with hydraulic fluid which transfers the force from the ram to the billet as shown in figure 3. Although tri-axial forces are applied by the fluid, the pressure improves billet formability on the billet. Sealing the fluid must be considered at the early stages to avoid any leaking and reduce pressure issues. Although the hydraulic fluid eliminates the friction between the wall and the billet by isolating them, due to the specialised equipment requirement, the high set-up time and low production rate limit its usage in the industry in comparison to other extrusion processes.
- 10. HYDROSTATICMETALEXTRUSIONADVANTAGES Low power/force requirement due to no friction Fast production rates & high reduction ratios Lower billet temperature Even flow of material due to the balanced force distribution Large billets and large cross-sections can be extruded No billet residue is left in the container
- 11. HYDROSTATICMETAL EXTRUSION DISADV ANT AGES Billets need preparing by tapering one end to match the die entry angle Only cold extrusion ispossible Difficult to contain the high- pressure fluid
- 12. Lateral extrusion In Lateral Extrusion,the container is in a vertical position as shown in the image and the die is located on the side. This process is suitable for low melting point material.
- 13. Impact Extrusion Impact extrusion is part of the cold extrusion category very similar to In-direct extrusion and limited to softer metals such as Lead, Aluminium and copper. As the schematic illustrates, the punch is pushed down at high speed and has extreme force on the slug to extrude backwards. The thickness of the Extrude is a function of the clearance between the punch and the die cavity. The Extrudates are slid off the punch by the use of a stripper plate.
- 14. For impact extrusions, a mechanical press is often used and the part is formed at a high speed and over a relatively short stroke Since the forces acting on the punch and die are extremely high, tooling must have sufficient impact resistance, fatigue resistance and strength, for extruding metal by the impact. Impact extrusion can be divided into the following three types by the flow of the material. Forward Reverse Combination In forward impact extrusion, the metal flows in the same direction that the force is delivered while it flows in the opposite direction in reverse impact extrusion. As the image shows above, in combination, the metal flows in both directions.
- 15. E X T R U S IO ND E F E C T S Depending on the material condition and process variables, extrudates can develop many types of defects that could affect the quality of the end product. These defects can be grouped under the following three defects. Surface cracking Piping Internal cracking
- 16. Presentation made by: Romil Shankar Gupta (08314803620) Priyanshu Ranjan (07614803620) Subject: Production Technology Subject code: ETME-205 Subject Faculty: Mr. Vikas Sharma Group: MAE 3rd semester M123