Impact extrusion is another important way to produce extruded profiles using metals. Contrary to conventional extrusion, that can only be operational at high temperatures for softening the material, Impact extrusion typically uses cold metal billets. These billets are extruded at high pressure. A typical Impact extrusion process works like this. A properly lubricated slug is put in a die cavity and then struck with a single stroke by a punch. This forces the metal to flow back around the punch, via an opening between the die and the punch. The impact extrusion best suits materials that are a bit softer like lead, aluminium or tin. An impact extrusion process is shown in the image below:
The impact extrusion process passes through the following stages:

Slugs(Raw material in the extrusion) 1	Impact Extrusion(Knuckle joint & hydraulic presses are used) 2
Heat Treatment(To adjust the mechanical Properties of the extruded parts) 3	Machining(Milling machines, CNC lathes) 4
Degreasing(Parts are cleaned) 5	Automated Assembly(assembly process automated) 6
Quality Control Process(Thoroughly automated) 7	Packaging(Use of advanced technical aids) 8

Extruded Parts Obtained by Impact Extrusion
Impact extrusion as a process particularly suits fabrication of parts that are found in their near-net-shape condition. Coming to the geometric forms that are typically impact extruded, there is a bit of limitation. The shapes are limited primarily to axially symmetrical cross sections, more precisely, in rotational symmetry. Interior forms of such parts may be axially symmetrical or even unsymmetrical to a certain extent. Some of the common shapes are shown in the images.


Advantages of Impact Extrusion
There is enormous advantages associated with impact extrusions. For convenience we have divided the benefits into two categories. Economic and technical.

Economic

• Low Tooling Costs
• Long Tool Life
• More Production Output
• Reduction in Material Usage
• A High Degree of Forming
• Savings on secondary operations
• Reduced cycle times

Technical

• Improved Physical Properties
• Precise Dimensional Accuracy
• Improved Surface Quality
• Corrosion Resistance
• Low in Weight
• Tighter Dimensional Tolerances

Types of Impact Extrusion
There are three types of Impact extrusion process. They are the following.

• Forward Extrusion
  Here the material is forced in a forward direction by the punch via an orifice in the die. This produces a smaller cross section as compared to the initial blank. Reductions to the tune of 75% can be made possible with this technique.
  
  
  
• Backward Extrusions
  Unlike Forward extrusion here the material is placed in the die and is forced in a backward direction around the punch. It produces blind holes and cups. of A 20-75% area reduction is possible in this method.
  
  
  
• Combined Extrusion
  This process effectively punches a combination of forward and reverse metal flows. This process best suits the formation of complex-shaped arts.
  
  
  

Market Applications for Impact Extrusion
A vast number of industries have a place for extruded products made out of impact extrusions. Some of the most popular industries include:

• Defence and Pyrotechnics
• Electrical/Electronic
• Automotive industry
• Speciality packaging
• Medical applications

Types of Forms typically produced by Impact Extrusion The following examples illustrate the forms that can be impact extruded from aluminium