Plasma Arc CuttingPlasma Arc Cutting

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Background of Plasma Arc ProcessBackground of Plasma Arc Process

In 1941 the U.S. defense In 1941 the U.S. defense industry was looking for a industry was looking for a way to join light metals, way to join light metals, from this came Tungsten from this came Tungsten Inert Gas (TIG) weldingInert Gas (TIG) welding

It was found that by It was found that by passing a gas through the passing a gas through the TIG arc that metal could be TIG arc that metal could be cut by gas in a plasma cut by gas in a plasma statestate

TIG and plasma arc TIG and plasma arc processes were created for processes were created for the aerospace industry, the aerospace industry, primarily for aluminum primarily for aluminum which is difficult to weld by which is difficult to weld by other processes and other processes and difficult to cut with a torchdifficult to cut with a torch CNC Plasma Cutting Machine,

1980

How a Plasma Cutter WorksHow a Plasma Cutter Works An arc is used to An arc is used to

ionize the gas around ionize the gas around a high voltage arca high voltage arc

This ionized This ionized gas is gas is superheated by the superheated by the arc to plasma (1)arc to plasma (1)

In the plasma state, In the plasma state, the gas is at 30,000˚F, the gas is at 30,000˚F, reducing the steel to a reducing the steel to a molten state, allowing molten state, allowing the stream of gas to the stream of gas to push it out of the cutpush it out of the cut

Advantages Plasma CuttingAdvantages Plasma Cutting

Super heat makes Super heat makes plasma cutting plasma cutting faster and more faster and more efficient than any efficient than any other form of other form of cutting. (2)cutting. (2)

Two Types of PACTwo Types of PAC Transferred Arc Transferred Arc

Process – the work Process – the work piece is part of the piece is part of the electrical circuit as in electrical circuit as in other arc processes. other arc processes. (3)(3)

Non-transferred Arc Non-transferred Arc Process – the work is Process – the work is not part of the circuit. not part of the circuit. The arc is generated The arc is generated inside the torch and inside the torch and nozzle.nozzle.

Most PACMost PAC

The simplest and most common form of PAC is the use of The simplest and most common form of PAC is the use of filtered compressed air (4)filtered compressed air (4) and cooling gases. and cooling gases.

When compressed air is used with a PAC unit, the correct air When compressed air is used with a PAC unit, the correct air flow rate and pressure are maintained by the air pressure flow rate and pressure are maintained by the air pressure regulator and filter/dryer on the power source. (14)regulator and filter/dryer on the power source. (14)

They use a pilot arc and the transferred arc process.(6)They use a pilot arc and the transferred arc process.(6) The most common PAC contains the following (7):The most common PAC contains the following (7):

• Retaining cupRetaining cup• Copper electrode with a hafnium thoriated tungsten Copper electrode with a hafnium thoriated tungsten

insertinsert• Gas swirl ring, andGas swirl ring, and• nozzlenozzle

Most PACMost PAC

The most common PAC PARTS THAT ARE The most common PAC PARTS THAT ARE CHANGED OUT ARE (8):CHANGED OUT ARE (8):• ELECTRODEELECTRODE• NOZZLENOZZLE

• MOST HEAVY DUTY PAC REQUIRE GAS:MOST HEAVY DUTY PAC REQUIRE GAS: ONE GAS CYLINDER CONTAINING THE CUTTING GAS AND ONE GAS CYLINDER CONTAINING THE CUTTING GAS AND

ANOTHER CONTAINING SHIELDING OR COOLING GASES. (11)ANOTHER CONTAINING SHIELDING OR COOLING GASES. (11)

• Sometimes they will hiss and sputter like an oxyfuel Sometimes they will hiss and sputter like an oxyfuel torch. This means that there is moisture entering the torch. This means that there is moisture entering the unit through the air line. (15)unit through the air line. (15)

SAFETY PACSAFETY PAC

The plasma cutter can get up to 30,000 degrees F.The plasma cutter can get up to 30,000 degrees F. In industrial uses it can cut up to 3” thick mild In industrial uses it can cut up to 3” thick mild

steelsteel. (5). (5) It will cut through gloves, never put hands under It will cut through gloves, never put hands under

the plasma arc or the work piece when cutting.the plasma arc or the work piece when cutting. Make sure plasma cutter power Is off before Make sure plasma cutter power Is off before

touching.touching. Safety glasses, full face mask, or helmet, same Safety glasses, full face mask, or helmet, same

rules as a apply to other arc processes.rules as a apply to other arc processes. Same PPE (leather, dark clothes, wool, cotton, Same PPE (leather, dark clothes, wool, cotton,

thick, boots, gloves, insulated).thick, boots, gloves, insulated).

SAFETY FIRE AND EXPLOSION SAFETY FIRE AND EXPLOSION WITH PACWITH PAC

CHECK FOR FLAMMABLES DUE TO SPARKS CHECK FOR FLAMMABLES DUE TO SPARKS (MATCHES AND LIGHTERS, ETC.)(MATCHES AND LIGHTERS, ETC.)

NEVER USE OXYGEN AS COMPRESSED AIR NEVER USE OXYGEN AS COMPRESSED AIR (BABOOM!)(BABOOM!)

A HYDROGEN GAS EXPLOSION EXPOSURE EXISTS A HYDROGEN GAS EXPLOSION EXPOSURE EXISTS IF USING A PAC NEAR A BETTERY. (9)IF USING A PAC NEAR A BETTERY. (9)

ALWAYS REMOVE CYLINDERS AND REPLACE ALWAYS REMOVE CYLINDERS AND REPLACE CYLINDER CAPS FROM PAC UNITS. (10)CYLINDER CAPS FROM PAC UNITS. (10)

SETTING FOR PACSETTING FOR PAC

CHECK THE METAL AND THICKNESS YOU ARE CHECK THE METAL AND THICKNESS YOU ARE CUTTING. THUIS WILL DICTATE THE SETTINGS:CUTTING. THUIS WILL DICTATE THE SETTINGS:• RATING MACHINERY USUALLY BY:RATING MACHINERY USUALLY BY:

DUTY CYCLEDUTY CYCLE MAXIMUM CUTTING CAPABILITYMAXIMUM CUTTING CAPABILITY

• IMPORTANT THAT YOU UNDERSTAND THE POWER IMPORTANT THAT YOU UNDERSTAND THE POWER SUPPLY REQUIRED AND LIMITATIONS BEFORE SUPPLY REQUIRED AND LIMITATIONS BEFORE COMMENCING CUTTING.COMMENCING CUTTING.

• RUNS ON DCENRUNS ON DCEN• MOST RUN ION 115 OR 230 VAC AND CUTTING THINNER MOST RUN ION 115 OR 230 VAC AND CUTTING THINNER

SHEET OF METAL, 14 TO 30 AMPSSHEET OF METAL, 14 TO 30 AMPS

SETTING FOR PACSETTING FOR PAC

CHECK THE METAL AND THICKNESS YOU ARE CHECK THE METAL AND THICKNESS YOU ARE CUTTING. THUIS WILL DICTATE THE SETTINGS:CUTTING. THUIS WILL DICTATE THE SETTINGS:• RATING MACHINERY USUALLY BY:RATING MACHINERY USUALLY BY:

DUTY CYCLEDUTY CYCLE MAXIMUM CUTTING CAPABILITYMAXIMUM CUTTING CAPABILITY

• IMPORTANT THAT YOU UNDERSTAND THE POWER IMPORTANT THAT YOU UNDERSTAND THE POWER SUPPLY REQUIRED AND LIMITATIONS BEFORE SUPPLY REQUIRED AND LIMITATIONS BEFORE COMMENCING CUTTING.COMMENCING CUTTING.

• RUNS ON DCENRUNS ON DCEN• MOST RUN ON 115 OR 230 VAC AND CUTTING THINNER MOST RUN ON 115 OR 230 VAC AND CUTTING THINNER

SHEET OF METAL, 14 TO 30 AMPSSHEET OF METAL, 14 TO 30 AMPS• HOWEVER A 2” ALUMINUM MAY REQUIRE UP TO 250 HOWEVER A 2” ALUMINUM MAY REQUIRE UP TO 250

AMPS. (12)AMPS. (12)

SETTING FOR PACSETTING FOR PAC

ANGLE IS ALSO AN IMPORTANT VARIABLE.ANGLE IS ALSO AN IMPORTANT VARIABLE.• THIN STEEL, USE 0 DEGREES ANGLE. (13)THIN STEEL, USE 0 DEGREES ANGLE. (13)

When compressed air is used with a PAC unit, the correct air flow rate and pressure are maintained by the air pressure regulator and filter/dryer on the power source.