Presentation on theme: "Plasma Arc Cutting Dr. L. K. Gaafar MENG 439. Plasma Arc Cutting PAC is a thermal material removal process that is primarily used for cutting thick."— Presentation transcript:
Plasma Arc Cutting PAC is a thermal material removal process that is primarily used for cutting thick sections of electrically conductive materials. Plasma can be defined as a “superheated, electrically ionized gas.”
PAC Process PAC uses a high velocity jet of plasma (Temperatures range from 10,000 to 14,000 o C) to cut through the metal by melting it. The high gas flow rate facilitate the removal of molten metal through the kerf Stream pressures can reach up to 1.4 MPa.
Gases Used Primary Gases: Gases that are used to create the plasma arc. Examples are nitrogen, argon, hydrogen, hydrogen, or mixture of them Secondary Gases or Water: Surrounds the electric arc to aid in confining it and removing the molten material.
System Components Torch Power Supply Arc Starting Circuit www.twi.co.uk/j32k/servlet/ getFile/jk51.html
System Components The torch is the holder of the consumable electrode and nozzle. Responsible for forming the arc and maintain it in a vortex. A. The Torch: Groover 626
System Components Types of Torches: Air Plasma Torch Oxygen-Injected Torch Water Injected Torch Dual Gas Torch A. The Torch:
Types of Torches Water Injected (Benedict 340)Air Plasma (Benedict 337)
System Components Constant DC current source. B. Power Supply:
High frequency generator circuit that produces a high AC Current. To start the arc, the AC current ionizes the cutting gas, which makes it conductive to allow the DC current to flow through it. System Components C. Arc Starting Circuit:
Types of Arcs 1. Transferred Arc: the generated arc is between the electrode and the work-piece. Benedict 336
Types of Arcs 2.Non-Transferred Arc: the generated arc is between the electrode and the nozzle and heat is carried to the work- piece by the plasma gas. Benedict 336
Advantages - Disadvantages Advantages - Disadvantages Cuts any metal. 5 to 10 times faster than oxy-fuel. 150 mm thickness ability. Easy to automate. Large heat affected zone. Rough Surfaces Difficult to produce sharp corners. Smoke and noise. Burr often results.
Applications Pipe industry – preparing pipe edges for welding. industries for shape cutting Cpam.engr.wesc.edu
Other Plasma Uses Plasma Arc Welding (PAW)- plasma arc is produced and aimed at the weld area to weld. Applications- Used for butt and lap joints because of higher energy concentrations and better arc stability.
Safety Precautions Machine the heat affected zone Regulate gas pressure Maintain constant distance between torch and work piece. High labor safety (i.e. goggles, gloves, etc…). Proper training for operators. Protection against glare, spatter and noise from the plasma.