1. Metal Cutting
Plasma
Oxy Fuel

2. Plasma Arc Cutting (PAC)
is a cutting process that uses an arc and a high-velocity, ionized gas coming through a nozzle to cut all metals that can not be cut with flame
Such as:
Stainless steel
Aluminum
Copper

3. PAC Plasma is a super heated gas that is ionized.
Ionized- Electrons in the gas have broken away form their atoms and will conduct electricity.
Gases used for plasma cutting includes:
Hydrogen
Argon
Nitrogen and mixture ,plus air and oxygen

4. PAC
How it cuts
The plasma gas (compressed air) is forced through a nozzle and heated by the arc which reaches to 5,0000°F

5. Advantages of PAC Can cut all metals Fast cutting speeds
Little distortion from heat
No hazardous gases
Oxygen based system do not leave nitride deposits
Nitrogen based systems are for aluminum, stainless steel and nickel

6. Disadvantages Plasma Torch is expensive
Not portable (needs electricity)
Metal fumes created can be a health hazard
Puts tremendous heat into the metal around the cut
Creates HAZ
Hardens materials next to the cut

7. Safety/ Maintenance A minimum of a #9 filter shield should be used
Need proper ventilation to remove harmful gases
Dip electrode into anti-spatter compound
Do not allow Pilot Arc to continue for long periods of time

8. Setting the PAC Torch If torch amps is set too high travel speed needs to be increased
Thickness
Current
Travel Speed
1/16”
35 amps
175 in/min
1/8”
40 amps
90 in/min
1/4”
40 in/min
80 amps
100 in/min
3/8”
18 in/min
55 in/min
1/2”
20 in/min
35 in/min

9. How to Use Clean metal Hook up ground cable
Draw cutting pattern on metal
Hold torch 1/16-1/8” from metal (torch stand will help maintain this)
Hold torch at a 70 to 90° angle
Pull button when arc begins pull torch across metal

10. Cutting Speed
Too Slow- Molten metal will collect on bottom of work piece and need to be ground off (this is called Dross)
Too Fast- Metal will not be cut all the way through

11. Oxy-Fuel Cutting

12. Oxy-Fuel Cutting, Welding
Definition:
Burning is the rapid oxidation of a material
Does Metal Burn?
Virtually all materials will burn if they are first heated to their ignition temperature.
Steel ignition temp is when it is cherry red, ° C
Oxygen burns preheated metal and blows it away from the work piece.

13. Oxyacetylene welding (OAW)
Oxygen and acetylene gas are mixed in the torch tip. The mixture burns at the torch tip.
The heat from this flame is used to melt the base metal and welding rod. This melted material forms a weld joint.

14. OFC Equipment Combination Cutting Torch with Cutting Attachment
Straight Cutting Torch

15. Cutting Tips
3690 Cutting Tip
3690-P Cutting Tip

16. OFC Cutting Tip Information

17. Oxy-Fuel Cutting Set-up
All set up the same as oxy-fuel welding except:
To set working pressure for oxygen must open cutting valve

18. Oxy-Fuel Cutting Process
Clean metal
Draw line
Make jig to keep cut straight
Hold tip 1/16-1/8” above metal
Preheat metal to cherry red color
Open oxygen valve and push torch through metal
(Angle tip slightly toward direction of cut)

19. Cutting Flame Types Carburizing Flame Neutral Flame
Neutral Flame with Oxygen Cutting Stream
Oxidizing Flame

20. Advantages
Can cut complex shape
Can cut carbon and low carbon steel
Inexpensive process
Can have multiple cutting torch
Disadvantages
It is slower than other cutting systems
Cut accuracy is not as good as plasma, water jet ,laser
Creates heat affected zone