Nitrogen Generators for Use in Plastic Manufacturing and Injection Molding
As the 3rd largest manufacturing industry in the United States, the plastics industry has a variety of applications that include the use of nitrogen gas. Nitrogen gas is used in plastic manufacturing to prevent oxidation and discoloring to help maintain the integrity of the polymer. Nitrogen is also used as a propellant to assist the injection molding process. These applications include gas assisted injection molding (GAIM), tank blanketing, and the extrusion process. South-Tek’s tested and proven PSA Nitrogen Generation Technology safely separates the readily available nitrogen from within the air we breathe.
The air contains 78% nitrogen; our systems mechanically filter out the other gases, concentrating the N2 into a storage tank for your process usage. Clean, dry compressed air enters one of the two adsorption vessels, containing Carbon Molecular Sieve (CMS). Smaller oxygen and residual molecules are adsorbed into the CMS, allowing the larger nitrogen molecules to pass through into a storage tank for later process use. Upon saturation, a second absorption vessel is brought on line while the first one regenerates and releases its trapped gas.
Gas Assist Injection Molding (GAIM):
This type of injection molding uses Nitrogen as the inert gas to push the polymer from the tank to the mold. This helps to completely fill out the part which also reduces shrinkage. The nitrogen gas gets pushed into the mold under high pressure which ensures that the polymer reaches all areas of the mold. Nitrogen can also be used as a propellant for blow molding applications where a hollow part is desired. By using nitrogen as a propellant, you are removing the ability for the polymer to come in contact with oxygen which reduces oxidation and discoloring of the polymer.
Plastic extrusion is the process of melting raw plastic material and pressing through a die to create a long, continuous shape which may be used for piping, tubing, weather stripping, and more. Oxygen in the extrusion process can result in residue that is harmful to the extruders. Nitrogen – a clean, dry, inert gas – is used to displace the oxygen and prevent damage to the equipment and final product.
Molten plastic is often housed in a tank prior to it being sent to the molding process. Nitrogen is used to blanket the tank which purges the oxygen away from the polymer. Nitrogen is also used in the hopper in the same capacity. When removing oxygen from coming into contact with the polymer, you eliminate oxidation and discoloration while improving performance.