73 terms
Plasma Arc Cutting
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A jet of plasma
What does a plasma arc cutting use to pierce, cut and gouge metal?
Manual or mechanized
What two settings can the Plasma Arc Cutting tool operate on?
Plasma Arc Cutting
What cutting method is ususally fastest and more efficient than any othe cutting method?
An electrical power supply and a cutting gas
What are two sources of power are required for a plasma arc cutting process?
By passing the gas through an electric arc inside the torch
How does a PAC (plasma arc cutting) torch convert the cutting gas into plasma?
30,000 degrees F or higher
What temperatures can a plasma cutting jet reach to?
Appropriate protective clothing and equipment
What should you be wearing when welding or cutting?
Safety glasses with a full face shield or a helmet, and have the proper light reducing tint for the type of welding or cutting
What should you always use on your face when welding or cutting?
Proper protective leather and/or flame-retardant clothing along with welding gloves to protect from flying sparks and molten metal, as well as heat
What protective gear should you wear on your body?
8" or taller
How high should your high-top safety shoes or boots be to be safe?
A solid material (non-mesh) hat with a bill pointing to the rear or a full leather hood with a welding face plate and the correct tinted lens
What type of hat or hood should be worn while welding or cutting?
An attachment for a rear defalctor material and a face sheild
What should a hard hat have to insure safety?
A face shield and snug-fitting welding goolges over safety glasses that include a shade of 5 or 6 filter
What should you wear if you are not wearing a leather hood when gas welding or cutting?
Matches or gas filled lighters
What is something you should NEVER carry in your pockets while welding is going on?
A hot-work permit and an approved fire watch established
What do you need before performing any type of heating, cutting, or welding?
The cutting torches
What is the cause of most work site fires in welding and cutting operations?
Oxygen
What do you never use to blow dirt or dust off of clothing?
Removed or covered by fire-resistant covering
Where should flammable material be in the work area?
requirements for a hot-work permit and/or fire watch
What should you comply with on any welding or cutting work site?
never release a large amount of oxygen or use oxygen as compressed air
What should you never do with oxygen?
Never release a large amount
What should you never do with fuel gas, especially acetylene?
Maintain a neat and clean work area, and make sure that any metal scrap or slag is cold before disposal
What are two ways to prevent fires on a work site?
If they contained any ecplosive, hazardous, or flammable materials.
before cutting or welding containers, what should you find out?
Make sure confined space procedures are followed
What should you do before conducting any welding or cutting in a confined space?
In a well-ventilated area and ventilated properly
Where should cutting or welding operations always be performed, especially in confined spaces?
Never use oxygen
What do you never use in a confined space for purposes of ventilation?
Transferred arc and nontransferred arc
What are the two types of plasma arc cutting processes?
To cut materials that are electrically conductive such as metals
What types of materials are cut when using the most common process of plasma arc cutting, which is transferred arc process?
To cut materials that are not electrically charged such as ceramics and concrete
What types of materials are cut when using the least commong type of plasma arc cutting which is nontransferred arc process?
The workpiece
In the transferred arc process, what is part of the electrical circuit, as in other arc processes?
Contact starting, discharge starting to the workpiece and discharge strating using a pilot arc
What are the different arc initiation methods used for the transfer process
Discharge starting using a pilot arc
What is the most common arc initiation methods used for the tranfer arc process that involves establishing a low-voltage and low-current, high-frequency (HF) arc is established between the electrode and the torch nozzle inside the torch?
To ionize the air jet
What is the pilot arc used for during a transferred arc process?
The entire arc is established within the torch, between the torch electrode and the torch nozzle, and the material in NOT electrically connected to the arc circuit
During a nontransferred arc process, where is the entire arc established and is the material being cut electrically connected to the arc circuit?
Power source control unit, plasma arc cutting torch with torch cable, work piece lead and lead assembly, plasma, shielding and cooling gases and gas control components
What items are included in Plasma Arc Cutting equipment?
A single-phase 115VAC or 230VAC outlet
What do PAC power source-control units typically plug into?
A range from 14 to 30 amperes
What is the typical maximum cutting amperages for light duty PAC power units?
35 percent range
What usual range is the duty cycle of light duty units?
Filtered, compressed air
What do the simplest power source units use for plasma and cooling gas
Stainless steel and aluminum up to 2 1/2" thick and carbon steel up to 3" thick
What can larger industrial power source units cut?
It contains their own closed-loop torch cooling system
What does it mean when a large industrial power source is water cooled?
A pilot arc and a transferred arc process
What do the most common plasma arc cutting torches us during cutting or welding?
So that the full voltage (potential) and current are not available
How is the torch current circuit designed in the torch between the electrode and nozzle?
A replaceable retaining cup, a copper electrode with a hafnium or thoriated tungsten insert, a gas swirl ring, and a nozzle (tip)
What does a typical plasma arc cutting torch usually contain?
On automatic carriers
How are mechanized PAC torches designed to be mounted?
the electrode and the nozzle
What are the most common parts that are changed in a torch?
O-ring, swirl ring, standard electrode, standard nozzle, retaining cup, then drag shield
What is the order that the parts are connected to the torch? ( Starting with the piece closest to the handle)
It provides the connection between the end of the work piece lead and the work piece
What does the work piece clamp provide?
well enough for good metal to metal contact
How well cleaned should the area where the clamp is being attached?
by the amperage that I can carry without overheating
How do you determine the size of the work piece?
It can cause serious damage to the item from arcing and overheating
What could happen if the cutting current passes through any type of bearing, seal, valve, contacting surface, or electrical or electronic component?
The battery must be removed to prevent hydrogen gas explosions caused by a cutting spark
What must be done when cutting near a battery?
One or more types of gases
What do all plasma arc cutting units require?
With the type, size, and manufacturer of the PAC equipment
How do the specific type of gases required and the controls necessary to set and adjust them vary?
Air, nitrogen, oxygen, argon and argon mixtures, hydrogen and carbon dioxide
What gases and gas mixtures are used with plasma arc cutting?
They use clean compressed air to cut carbon steel, stainless steel and aluminum up to about 3/16" thick
What gases are used in the simplest PAC units?
One gas may be used for the pilot arc and for cutting and the other shielding or cooling
Why do some dual flow PAC units use two different gases?
They must have their pressures reduced before they can be used
What must be done to all gases before use?
1,500 psi to 2,000 psi
What PSI are gases supplied in high pressure cylinders, that are not compressed air?
With the solenoid valve that electrically opens and closes a gas valve
How is the stop start flow control to the torch usually controlled?
inside the unit and are controlled by a pushbutton on the torch
Where are the solenoid valve usually mounted and how are they controlled?
The unit must have the rated power and duty cycle to cut the intended metal type and thickness, the required primary power (phase, voltage, amperage) must be available for the control unit, the required nozzle must be installed in the torch, the required gas or gases must be online and at the required pressures and flow rates, and spare consumable components must be on hand
What should you consider and what preparations should be completed before cutting is attempted?
the type of equipment being used, the type and thickness of the material being cut, and the type of gas being used
What does the cutting amperage depend on?
You refer to the manufacturers recommendations
What do you refer to when determining the cutting amperage?
It will result in a poor quality cut and severe damage to the torch will occur
What will happen if you use the incorrect amperage or amperage that is too high?
By holding the torch at 90 degrees ( 0 degree working angle) to the metal surface while it is advanced smoothly, with no side-to-side movement
How are square edges cut with PAC?
The cut angle
What is the angle of the face known as?
Hold the torch directly over the point to be pierced at a 0 degree work angle and press the arc button. As soon as the jet passes completely through the work piece move the torch head in a smooth circle (or pattern) to produce the desired diameter or shape for the hole
How do you pierce very thin metal?
Rotate the torch to a 10-degree work angle to prevent metal from splashing directly up into the torch and when the jet passes through the work piece rotate the torch to a 0-degree work angle and complete the cut
How do you pierce thicker materials ?
A template or straightedge
What can be used when cutting slot to precisely guide the torch tip?
Shop Air and the air pressure regulator and filter/dryer on the power source
What can be used with a PAC unit if compressed air is used, as long as it is dry and free of oil, and what will maintain the correct pressure and flow rate for the system?
That moisture may enter the unit through the air line which can cause the torch to sputter or hiss
Why is it a significant concern, when using the PAC equipment ?
Drain the filter bowl, replace the filter element, if has one, and refer to the manufacturer's literature for cleaning and replacing this filter
What do you do if your PAC equipment experiences moisture problems?