Shop Flashcards
How close do you put your tungsten to material ?
Same diameter as tungsten
What tungsten is used for aluminum ?
Zirconium oxide (zirconia )
How are tungsten’s identified ?
Colour
What happens if Argon gas displaces your air supply ?
You could be asphyxiated
What percent is argon helium?
80% argon 20% helium
For most sheet metal projects a gas flow setting of _____ is a good starting point ?
20 cubic feet per hour
What’s the first thing u enter into the plasma table ?
Duct dimension
What is the most common satey feature on the plasma table ?
Nozzle in place saftey sensor
What type of metals can be cut using plasma arc ?
Almost all metals
What is the main advantage of using computerized layout ?
Speed (productivity)
What is the main advantage of using computerized layout ?
Speed (productivity)
Describe the plasma cutting process
Uses a high velocity jet of ionized gas , electricity is conducted through the plasma and melts the material
What can be done if it’s not possible to pattern into a template directory ?
Use a hand held plasma
Other than plasma cutters list 4 types of cutting equipment that is used in the sheet metal trade ?
Oxy fuel
Laser punch
Water jet
Router
Why is it important to nest fittings into the material being used for plasma cutting ?
Optimize material usage
What does nesting mean
The parts are laid side by side and rotated to match interlocking angles and contours
What are some process parameters that can be modified to obtain desired results ?
Kerf
Lead in
Lead out
Feed rate
What are some advantages of using customized labels ?
Extra critical data for estimating
Production
Shipping
Inventory
Management
Purchasing
List some ppe that should be worn for using computer cutting equipment
Long sleeve
Gloves
Eye protection
Follow all safety tops and guide lines
Why is it important to find a machine that uses a “ nozzel in place safety sensor “
The plasma cutter will not start an arc unless the nozzel is in place
How was plasma cutting discovered ?
Accidentally trying to develope a better welding process
What is the function of an electrode ?
Carry the negative charge from the power supply
What is the function of the gas distributior
To spin the plasma gas into a stable vortex of swirling gas
What is the function of a nozzel
Constrict and focus the plasma jet
What is the function of a shield ?
Protect the nozzel from spatter and focus the shield gas jet
What parts of the plasma need frequent replacement?
Nozzle and electrode
What changes on a plasma machine as we start to cut thicker materials
Amperage
How are cutting speeds measured ?
Inches per minute
How are consumables rated ?
Some rate consumables by number of cuts while others use number of starts
What is the advantage to use ing a smaller torch ?
Better see where you are cutting
Why do we need to filter the compressed air when useing a plasma cutter?
They ensure oil is removed from the compressed air
What can be the result of having oil in the compressed air when plasma cutting ?
Oil can cause arcing and reduce cutting performance and it will also reduce the life of consumables
What two dimensions are affected by the plasma cutter on a part being cut ?
Kerf width
Bevel angle
What is kerf ?
A void created by the plasma cutting processes or the amount of metal removed by the plasma arc
What four things can affect the plasma arc kerf ?
Amperage
Voltage
Gas flow
Velocity of moving torch
How are nozzles sized ?
According to amperage rating
The bigger the hole the more power it can handle
What problems can happen if the kerf is to wide ?
Worm nozzle
High torch standoff
Excessive amperage
Inadequate gas flow
Low speed
What is the problem if the kerf is to narrow
Low torch standoff
inadequate amperage
Excessive gas flow
High speed
What is bevel angle ?
The angle of the cut edge
When is a bevel angle starting to show problems with the machine parameters ?
When the angle is greater than 5 degrees may indicate a problem with the pac machine parameters
Whay can cause a positive bevel ?
Part top is smaller than the bottom
What can cause a negative bevel ?
Smaller bottom and bigger top
What can cause an irregular bevel ?
The presence of both positive and negative bevel on the same peice
What is dross ?
Re -solidified oxidized molten metal that is not fully ejected from the kerf during cutting
How can we eliminate “ low speed dross “
Increase cut speed 5ipm increments
Increase standoff in 5 volt increments
Decrease the amperage in 10amp increments
If none of these improve the cut consider another nozzel
How can we eliminate high speed dross ?
CHeck nozzles for sighns of wear
Decrease cutting speed 5ipm increments
Decrease the stand off in 5 volt increments
Increase ether amperage ( do not exceed 95% of the nozzle office rateing )
How can we eliminate top splatter dross ?
Check the nozzel for sighns of wear
Decrease the cutting sped in 5ipm increments
Decrease the standoff in 5 volt increments
What can be done to machines and equitment that are being used to form sheet metal fittings ?
Heat treat and harden the machine parts that come in contact with these edges
What can be done to the actual fitting pieces prior to using convention sheet metal equitment to prevent damage ?
Dross should be mechanically removed by grinding or filling to minimize wearing out ewuitment rollers and guides
What is some information that can be put on a label that will be attached to a fitting part ?
Job name
Address
Floor
Location
Fitting number
Which truck it should be loaded
What name is most commonly given to gas tungsten welding ?
Tig
Describe the welding process for gas tungsten arc welding ?
Fusion welding is accomplished by the heat of an electric arc drawn between a non consumable tungsten electrode and the work
Is gtwa more hazardous than any other welding process?
No
What four main safety precautions should be taken in respect to prior and during gtaw welding process?
Electrical hazards
Eye protection
Protective clothing
Ventilation
What should be checked prior to welding to prevent electrical shock ?
Check all electrical connections to ensure that they are properly made to avoid the possibility of electric shocks
How often should we check all current carrying components required for gtaw ?
Regularly
What must be in place prior to welding ?
All protective covers must be in place
Does the welding machine need to be properly grounded ?
Yes
How do we know what size torch needs to be used ?
Must be large enough to handle the amount of current used without overheating
What should be checked for on water cooled torch heads ?
All connections for leaks
List three things that are required of the work leads prior to using them for the welding process
Work leads should be in good conditions
Work leads should be large enough to handle the current used
The work lead should be firmly connected to the work to prevent accidental arcing
List three safety items that must be considered in regards to the hose or cables in the work space
Must be protected from hot materials or falling objects
Should be hung up out of the way when not in use
Leave the work area clear of obstacles and possible tripping hazards
Why should you turn the power off to the welder when not in use?
To prevent accidental arcing
Why is it important to have dry gloves and footwear and footwear when welding ?
Perspiration can cause gloves to become conductors. Ensure that gloves and footwear are dry and in good conditions
What needs to be done if u are welding in wet weather conditions or are standing on a wet surface ?
Take the necessary precautions to protect
In what scenario is the most intense ultraviolet radiant energy produced ?
When Argon shielding gas is used and when aluminum or stainless steel is being welded
What shade of welding lens is required for welding ?
Use the darkest shade that is comfortable, but not lighter than recommended
What can happen to exposed skin that is not covered during the welding process?
Shinny surfaces can cause a sunburn effect to exposed skin
When working inside a tank or confined space what should we be careful to also protect from bright light ?
Back of kneck and ears
Who outlines acceptable noises levels in a working environment?
Provincial occupational health and safety standards
What type and color of clothing is preferd when welding ?
Dark coloured tightly woven clothing
What can be the results of wearing a light colour of clothing that can reflect light ?
More reflective and may cause burns to your eyes even when a helmet is worn
Why should synthetic clothing be avoided when welding ?
They tend to flash (burn rapidly)
List two considerations that must be met when selecting clothing used for welding ?
Relatively flame resistant
Free of any oil or grease
Why is it important to keep collar buttoned and yiur pockets and cuffs covered when welding ?
To prevent the entry of sparks
What should never be in your pockets when welding
Matches or lighters
What type of glove is required for gtaw welding
Gauntlet gloves of an approved type to protect your wrist and lower arms
What must a welder have readily available for fire prevention
Suitable fire extinguisher
Why is it important to have the exhaust ventilation several inches away from the welding area ?
So the ventilation does not disturb the gas shield
What is the maximum feet per minute that should be maintained over the surface of the welding area ?
50fpm
Why do certain cylinders and regulators have diffrent sizes and types of connections?
To eliminate the possibility of interchanging regulators to cylinders
Why is it important on how we store liquid and gas cylinders
To prevent the incorrect uses of gases
What two important pieces of information must be attached to every cylinder containing liquids or gasses used for welding ?
To identify the gas
Must have who is symbols attached
Where are two locations that we can store gas and liquid cylinders ?
Outdoors or in a well ventilated area
How should gas and liquid cylinders be secured when storing transporting or being used for welding ?
Vertical upright position
What 3 things need to be done to gas and liquid cylinders prior to returning them ?
Ensure valves are closed
Protective caps are in place
Outlet cap or plus replaced
What four things are protected from atmospheric contamination by the gaseous shield when tig welding ?
Electrode
Arc
Weld puddle
Adjacent heated area of the work place
Do we always need to use filler rod when tig welding ?
No
Why was tig welding originally developed ?
Towels corrosion resistant and hard to weld metals such as aluminum and magnesium
What delivers the heat between the electrode and the work prove ?
The arc
How is filler rod inserted into the welding puddle when heated ?
It is added separately either manually or automatically
When would tig welding be the preferred welding process ?
When highest possible quality welds are required for the more critical weld applications
List four types of gtaw power sources ?
Transformers
Transformers/rectifers
Generators
Inverter type
Which gtwa power source are best suited and most commonly used in our industry ?
Transformers/rectifers designed for gtaw
Which type of current is generally used for welding aluminum and magnesium
Alternating current
Which type of current is generally used for welding ferrous metal and some non ferrous metals ?
Direct current straight polarity
What can be used on specific gtaw workstations to control gas flow cooling media and current ?
Remote control units
When using a remote foot control on a gtaw workstation what restricts the maximum amount of current that will be delivered to the workpiece ?
Amperage adjustment control
What are three things that are controlled by the remote control unit attached to the torch handle ?
The main contractor
Shielding gas flow
Amperage
What are two methods of cooling the torch on a gtaw unit ?
Air cooled
Water cooled
What is the difference between the power cable thickness on an air cooled torch assembly compared to a water cooled torch assembly
The power cable of an air cooled torch is heavier than that used in a water cooled torch assembly
Why is one torches power cables thicker than other ?
Water cooled torch assembly can maintain cooler temperature
What is the maximum amount of amperage that is recommended to be ran through the power cables of an air cooled torch head assembly?
200amps
In regrades to the electrode what is the advantage of useing a water cooled torch head assembly opposed to an air cooled torch head assembly ?
Lower electrode Tempature and less electrode erosion
Can the water cooled torch head assembly carry more or less amperage in comparison to the air cooled torch assembly?
More
What are the advantages of having a flexiabke torch head assembly ?
Allow you to adjust the head angle for your comfort and better joint access
What is the most common torch head angle used in gtaw?
120
What are three functions of the torch cap ?
Prevents accidental arcing of the tungsten electrode at the back of the torch
Used to tighten. The collet onto the electrode
Give a positive shielding gas seal between the torch cap and body
What are five components that make up an air cooled and / or water cooled torch body ?
Handle
A means of conveying shield gas
Collet body connection
A metal body to transfer power from the cable to the collet body
Cooling lines
What three things are normally included in the torch body ?
Cables
Hoses
Machine connectors
List three functions of the collet body
Holds electrode collet to position the electrode in the torch
Establish electrical contact between torch body and electrode collet
Directs shielding gas to the gas nozzel
In regards to the electrode what are two functions of the collet ?
Positioning electrode
Makeing positive electrode contact
What transfers the electrical current from the collet body to the electrode ?
The collet
How is the tapered end of the collet pushed into the collet body resulting in tighting around the electrode ?
Tighting the back end cap
What are most collets made from ?
Copper alloy
What is the result of using mismatched collet bodies and collets ?
Damage to the collet occours and the electrode cannot be held in position
What is the function of a gas nozzle
To direct shielding gas into the weld zone
What type of nozzle is the most common and why ?
Ceramic type which is also the least costly
What is a major disadvantage of using a ceramic type nozel ?
They become brittle after repeated use and cause chipping and uneven gas flow ?
What are two considerations that must be taken into account when selecting a gas nozzle ?
Size of electrode
Size of puddle
What are four advantages of using a smaller nozzle ?
Maintain a more stable arc
Give the welder better vision
Give a compression effect to the arc
Permit welding in restricted areas
What is the main advantage of using a larger nozzel ?
Give a better shielding action at lower gas flows rates
What metal are normally welding useing a larger nozzle ?
Metals that oxide readily at elevated temps
List three other types of nozzels available but ware not commonly used in the sheet metal industry ?
Alumina gas nozzles
Fused quartz nozzles
Sleeve type metal nozzles of the slip on style
What can result in not keeping the nozzle clean ?
Building of foreign matter results in turbulence in the gas flow and contamination of the weld puddle if this foreign matter falls into weld pool
What is the result of using a gas lens inside a nozzle
Produce a longer undisturbed plume of gas
What is meant by gas flowing in a laminar fashion ?
Arranged in thin layers
By useing a gas lens will the distance between the work and nozzel increase or decrease ?
Greater nozel to work distances
What can cause a gas lens to disrupt gas flow ?
Fine spatter or other contaminants
What is imperative of the use of a work lead ?
Must have clean contact surfaces and must make good electrical contact with the work peice
What defines an electrode ?
Picks up or emits electrons in an electrical circuit
What type of electrode is used in a gtaw process ?
A non consumable tungsten electrode ?
What is the purpose of an electrode when used in the GTAW process ?
Transfer electrical current across the arc between the elctrode and the work
Why is tungsten used as an electrode ?
It is a highly refractory ( heat resistant) metal with a melting point of 3410 degrees delicious which is the highest melting point of all metals
How are the sizes of tungsten expressed ?
Diameter and length
How has the American welding society developed a system to quickly identify the diffrent alloyed tungsten used for GTAW?
Numbering and colour code system to identify each electrode
What two types of finishes are electrodes manufactured in ?
Ground
Chemically cleaned
What are two factors that can affect current ranges ?
Material type
Thickness
What is the main purpose of a shielding gas ?
Exclude the atmosphere from the weld puddle
What is the result of atmospheric air entering the molten metal ?
Porosity hardening and embrittlement in the weld
List three gases that are normally used in the GTAW process ?
Argon
Helium
Argon helium
Is argon heavier or lighter than air ?
Argon is 1.4 times as heavy as air
What could be the result of argon replacing oxygen in the work area ?
You could be asphyxiated
List 3 applications where helium would be the gas used for GTAW process ?
Heavier sections
Higher thermal conductive metals
Automatic high production welding
What is the percentage of argon and helium in a mixed gas used for GTAW ?
80% argon and 20%helium
Where would an argon helium mixture be a good choice for shielding gas used?
Stainless steel and non ferrous metals Automatic high
What is the main disadvantage of using argon helium mixture ?
Cost
What are two ways that shielding gases are stored?
High pressure cylinder
Bulk liquid system
What type of label must be on gas cuylinder ?
WHMIS symbol indicating gas type
In what position should a gas cylinder be used ?
Vertical position
In what position should gas cylinder valves be opened to ?
Opened fully
What two ranges are regulators designed to work within ?
Pressures
Volume
What do regulators control ?
Control pressure
Not flow rates
What regulates the flow rate of a shielding gas?
Flow meters
How are flow meters calibrated to indicate ?
Litres per minute or in cubic feet per hour
What is the difference between a regulator and flow meter in terms of what they indicate ?
Flow meters indicate volume flow while regulators indicate pressure
Why are flow meters designed and calibrated for specific gases ?
Because of Thier diffrent density’s
Why are gauges on a gauge style combination regulator /flowmeter not as accurate as a flow tube style flow meter ?
They operate on pressure converted to volume
Why are plastic hoses used for helium shielding gas opposed to rubber hoses ?
Rubber will allow helium pressurized to above 138kpa (20psi) to penetrate through the hose and cause gas loss
What does the solenoid valve control ?
Shielding gas and coolant flow
List four ways that filler materials can be avalliable for gtaw ?
Straight rods
Flattened rods
Spooled wire
Consumable inserts
What is the range of diameters that filler rod used for tig can be ordered ?
1.6mm to 6.4mm (1/16to 1/4 inch)
How are diffrent types of filler rods identified ?
Attached tags or stamped impressions
What just the filler rod match in relation to the base metal being welded ?
Match or exceed the base metal properties
Under normal circumstances die’s filler rod require any specific preparation prior to welding ?
No
Where should the hot end of the filler rod be located during welding ?
Protected by the inert shielding gas during welding to reduce atmospheric contamination
Where should filler rod be stored when not being used ?
Remain in Thier containers until required for service
