Free extrusion process is particularly useful in extruding simple solid round or profiles that are flat strip. However there is some sort of doubt if it can be used equally for extruding complex profiles. Here, the tooling costs are more or less cheap. If parameters like a proper die design, accurate control of air pressure, water temperature, belt-puller speed etc are properly adhered to then it is quite possible for free extrusion to provide perfect means for having profiles with high degree of tight diameter tolerances. A typical Free extrusion process works like this, the extrusion takes shape by its entry into a water quench tank. There is a guide plate that controls water flow and rollers are used to keep the product submerged. This method is most suitable for small diameter tubing and rod, and other cross-sections with lesser complications. In case of tubing, to prevent any chance of collapsing adequate arrangement is to be made so that inside of it must be vented to the atmosphere or provided with some sort of low positive pressure.

The die orifice that is used in the process of free extrusion is typically oversized, this allows a higher drawdown. Low internal air pressure is introduced in the tube via the inside die ring, this helps to have a more precise control of the dimensions.


Features of Free extrusion
Free extrusion into water is one of the most efficient ways to manufacture tubings with small diameter. Some of the features include:

• High production rate that can go up to 137m/min(450fpm).
• Close tolerances around 0.04mm(+0.0015inch).
• Diameters of 3.2mm is also obtainable in tubing.
• Restrained internal stress levels.

Types of Free Extrusion
Free extrusion of tubing generally takes two forms. They are:

• Free Horizontal Extrusion
  In this type of Free extrusion, the tube is extruded directly into the water bath horizontally. This process is shown below:
  
  
• Free Vertical Extrusion
  In this type of Free extrusion the tube is extruded directly into the water by using a vertical method. The image is shown below: