1. MENG 439
Dr. L. K. Gaafar
Plasma Arc Cutting

2. 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.”

3. PAC Process
PAC uses a high velocity jet of plasma (Temperatures range from 10,000 to 14,000 oC) 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.

4. 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.

5. www.twi.co.uk/j32k/servlet/ getFile/jk51.html
System Components
Torch
Power Supply
Arc Starting Circuit
getFile/jk51.html

6. System Components A. The Torch:
The torch is the holder of the consumable electrode and nozzle.
Responsible for forming the arc and maintain it in a vortex.
Groover 626

7. System Components A. The Torch: Types of Torches: Air Plasma Torch
Oxygen-Injected Torch
Water Injected Torch
Dual Gas Torch

8. Types of Torches Air Plasma (Benedict 337)
Water Injected (Benedict 340)

9. System Components
B. Power Supply:
Constant DC current source.

10. System Components C. Arc Starting Circuit:
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.

11. Types of Arcs Transferred Arc:
the generated arc is between the electrode and the work-piece.
Benedict 336

12. 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

13. 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.

14. Applications Pipe industry – preparing pipe edges for welding.
industries for shape cutting
Cpam.engr.wesc.edu

15. 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.

16. 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.

17. THANK YOU STUDENTS