1. Extrusion Submitted to: submitted by:
Asst. Prof. M.P.Gururajan Koduri Srikrishna
(2008AMD2922)

2. Introduction Joseph Bramah, developer of extrusion process.
It is a process by which a material is forced to flow through a die, which is shaped to produce the required cross-section.
It is similar to the squeezing action of tooth paste.
Courtesy: google images(direct extrusion)

3. Types of extrusion Hot extrusion Cold extrusion
At elevated temperature
No work hardening
costly
Cold extrusion
At room temperature
Work hardening
Lack of oxidation, good surface finish.

4. Direct extrusion

5. Indirect extrusion
Courtesy: google images (indirect extrusion)

6. Indirect extrusion Advantages: Disadvantages: Reduction of friction
high contianer’s life
billet moves more uniformly. So, less extrusion defects
Disadvantages:
Impurities and defects on surface.
Length and area of extrusion depends on stem.

7. Hydrostatic extrusion

8. Extrusion force curves
courtesy: wiki Fig: relations between forces applied and ram displacement in various processes

9. Copper alloys Composition of copper used is 55 to 65%
As copper content increases, ease of extrusion decreases.
In order to have hot working, Lead content should be low oC
Pressure-690MPa
Tubes of 11cm outer diameter, with thickness of 2mm.
Free cutting brass, hot stamping brass
Manganese bronze alloys has marine applications

10. Steels 1100 to1250oC Dummy preheated to 800 to 900oC Glass lubrication
Plain carbon steels to high alloyed steels
Tubes of 20m long, diameter of 10mm,20mm.

11. Aluminium alloy 300 to600oC Press- 500 to 6000Tons
Billets of 75mm diameter for small,1100mm diameter for big presses.
A layer of metal remains on the surface after extrusion.
Lubricants- graphite, molybdenum disulphide

12. Properties of materials
Presence of impurities, gas, dross, etc
Depending on degree of deformation
Deformation is greater in outer zones.
Therefore, differences in properties at these places.
This variation is high, if extrusion ratio is low.
Temperature at which work is carried out.
Bismuth is brittle in cast state, but, it can be extruded without difficulty at 40oC

13. Extrusion defects
Surface cracking
Piping defect
Internal cracking

14. Thank you