Plasma Arc Melting (PAM) Furnaces

Plasma is the fourth state of matter whereby a gas is electrically excited via a DC arc producing a high energy plume that can be used to melt metals and alloys. That arc can be transferred to a work piece to aid in melting or the arc can be non-transferred, or contained within the torch, thereby causing the plasmated gas plume to accomplish all of the melting. Examples of plasma in everyday life are lightning, Neon lights and television sets.

A Retech PAM Cold Hearth furnace uses an electrically excited gas, typically Helium, Argon, or Nitrogen to melt materials in a sealed chamber, under inert atmosphere and offers significant cost savings by eliminating the need for electrode welding and primary Vacuum Arc Remelting. The Cold Hearth is a water-cooled, copper vessel that is devoid of contaminating elements like Oxygen and yields clean, as-cast metal by removing high- and low-density inclusions during cold hearth refining.

Yes. Retech has three types of guns in four different sizes. The customer application and the system design will ultimately determine which type of torch to employ.

Retech Plasma Melting Systems have primarily been utilized for melting reactive and refractory metals and alloys (like Titanium & Titanium Alloys) though ongoing plasma research and development programs have melted countless specialty materials for our customers. Plasma furnaces can be designed for a wide range of sizes, from a few pounds to many tons, as well as production of everything from ingots and powder to castings. Our plasma arc melting furnaces can be configured with one or multiple torches, any number of feed systems as well as casting and withdrawal chambers to meet the needs of our customers.

The PAM process is different from other melting techniques in that it does not take place in deep vacuum, instead it is in an atmosphere of inert gas. This allows the process to fully melt and refine alloys that contain low vaporization elements.

PAM applications are generally melting and remelting of alloys containing a large number of elements with high vapor pressure that would evaporate under deep vacuum. Additionally, rotor-grade alloys for aerospace typically require plasma melting due to the ability to remove high- and low-density inclusions.

Plasma torch applications include cold hearth refining as well as recycling (PAM), consolidation (PAM), welding (PAW), atomization and waste treatment (PACT).

The inert gas enters the plasma torch and is excited using DC power to the "plasma state" and directed at the workpiece where the heat of the plasma will melt the material. Additionally, the plasma acts as a conductor to allow the energy to flow between the torch and the workpiece. The current flowing through the workpiece increases the energy into the workpiece.

Typically, the PAM furnace is configured as a cold hearth refining system. The material will be melted in the hearth and refined as it is continuously cast into an ingot. Ingots can range from 50mm up to 1000mm in diameter and can exceed 5m in length depending on the final application requirements.