Shop Flashcards
What metals can be cut using a plasma arc ?
Almost all metals
What is the plasma cutting process?
Process that uses a high velocity jet of ionized gas delivers from a constricting orfice
What is a computerized duct lay out program ?
Program linked with the plasma cutter that often has hundreds of preprogrammed basic and complex fitting shapes. Is capable of mitring reducing and dimensions as well as select seam placement. Selecting the template allows you to enter all dimensions you may require. Once you have finished u click auto nest and the computer will automatically nest the material for the least amount of wasted
What is a standard component library ?
Includes items such as
Lifting lugs
Belt guards
Flanges
Gussets
Can housing
Augers
Can you design your own labels ?
Yes you can to use later to extract critical info for estimating shipping and assembly
What are some safety practices when operating the plasma ?
Long sleeve
Gloves
Eye protection (dark goggles or welding mask)
Shade of 7 or 9 is acceptable
What is the nozzle in place safety feature?
An arc will not start unless the nozzle is in place
What is another consideration when purchasing a plasma ?
Look for machine that provides pre flow sequences
What are the 5 components of the plasma ?
Shield
Retains cap
Nozzle
Electrode
Swirl ring
What are the consumables on a plasma machine ?
Electrode
Nozzle
What guidelines should you follow when selecting a machine
Determine metal thickness
Select best cutting speed
Look for portability factor
Determine durability
If you cut thick metal what amperage machine should you get ?
A high amperage machine
What is the cutting speed measured in ?
Inches per minute
What is kerf ?
The void created by plasma cutting process or the amount of metal removed by the plasma
Changes due to every factor
What is kerf angle ?
Kerf width and bevel angle
How are nozzles sized for plasma ?
According to amperage rateing
What if kerf angle is too wide ?
Meaning that the part is to small it can be caused by
Worn nozzle
High torch standoff
Excessive amperage
Inadequate gas flow or low speed
What if kerf angle is too narrow ?
Low torch standoff
Excessive gas flow or high speed
What is a bevel angle ?
The angle of the cut edge.
A cut with zero degree bevel is a straight cut
Typically bevel angles range from 1-3 on the good side of the cut and 3-8 on the bad side
What would cause a positive and negative and irregular bevel ?
Positive = high torch standoff Excessive off worn nozzle excessive speed
Negative= caused by low torch standoff excessive amperage or low speed
Irregular = means the nozzle has failed
What is dross ?
Molten metal that had hardened before it was ejected from the cut
Slag/ bur
What happens when the chromium content exceeds 11% on stainless steel?
An invisable film is formed and protects the material
Can stainless steel rust and if so how ?
Yes when the film is contaminated by iron
What elements can be in stainless steel ?
Chromium
Nickle
Manganese
Molybdenum
Carbon
What are 4 groups of stainless steel ?
Austenitic
Feeritic
Duplex
Martensitic
What is duplex steel ?
Combination of austenitic and ferritic alloy, either 300 or 400 series contain a high chromium content also known as as ferritic and austenitic alloy
How many groups and series are the for stainless steel ?
4 groups and 2 series
What is ferritic steel ?
Magnetic steel or 400 series stainless steel which chromium content of 11-18%. It contains no nickle and is used for automobile trim exhaust hot water tanks
What is austenitic steel ?
Non magnetic or 300 series that has a chromium content of 16-25% and a nickle content of 6-22% most common type of stainless used in sheet metal trade
What is martensitic steel ?
Magnetic steel or 400 series that has chromium content of 12-18% and high carbon content. Used in surgical instruments spindles pins
What are some advantages of stainless steel ?
Hugh resistance to corrosion
Can take a high polish
What are some disadvantages of stainless steel?
Cost
Workability
Labour required
What are the most common stainless steel types ?
304 and 316
How is stainless steel listed ?
Chromium is listed first and nickle is listed second
What is mill rolled 2b?
Produced the same as 2d however it is passed through a polished roll to provide a more reflective finish
What is mill polished 4 ? And what grit do we use ?
Widely used for resturant equitment kitchen equitment and has a grit that is hard to reproduce
Grit used 100-150
What is mill polished number 8? What grit do u use ?
Grit line free surface achieved by extensively buffing. Most produced finish like a mirror
320 grit
What must be done when working with stainless steel?
Sweats the equitment by 2 working gauges or 4 gauges
Should you use a debuting tool on stainless steel ?
Yes when stainless steel is cut it leaves a burr which makes fit up and welding harder
How many teeth should be in contact with the material for cutting stainless with saw ?
Atleast 2 teeth should always be in contact
What should the included angle of a drill bit be when working with stainless steel ?
130 to 140 degrees
Whst should be done when punching stainless steel ?
Twice the amount of force is required compared to mild steel therefore speed of travel should be reduced by 50%
Is band sawing a good choice for stainless steel?
Yes
What is the purpose of the squaring shear ?
Must be derated 4 gauges and most shops that do excessive steel install hardened blades. The blade clearance should be reduced to the manufacturer specified a recommended gap for lighter stainless is 0.001 to 0.0015 and for heavier it should be 0.0015 to 0.002
What is spring back ?
The elasticity of the material when bending you must over bend to accommodate
What are two ways to bend stainless steel ?
Air bending and coining
What is the correct bend radius setting for a brake with stainless steel?
1 metal thickness
What is a power brake ?
Will require more pressure to complete a bend and Thier capacity will decrease. Air bending and bottom bending are both acceptable methods
Does bottom bending scratch the surface ?
Although bottom bending is more consistent it leaves scratches and scars
What 2 advantages does air bending have ?
Less pressure required to complete bend
Fewer scars and scratches
Can you use bench machines with stainless steel ?
Most are limited to light gauge materials use extreme caution
What methods can be used to fasten stainless ?
Rivets bolts nails soldering Lloyd’s flux soft soldering hard soldering brazing welding and spot welding. SMAW also know as stick welding. GTAW also know as tig welding and MIG
What must be done if spot welding stainless ?
Increases pressure and lower appearance and current flow
How much should u be able to bend a spot weld ?
60 to 90
What type of current should be used when welding stainless steel ?
DCEN also know as straight polarity. When deep penetration is needed you can use reverse polarity
What can be used for distortion control when welding stainless ?
Copper chill plate sand aluminum backing
What is the heat expansion properties of stainless steel?
50%greater than mild steel while having a third as great heat conductivity of mild steel
What type of welding should be used when welding stainless ?
skip welding
Stich welding which consists of makeing a short weld then skipping
What is stepback welding ?
Each bead is welded into the cooled end of the previous weld
What is the finishing procedure of stainless steel?
Grinding
Sanding
Polishing
Buffing
When punching stainless steel what should the minimum hole diameter be ?
Should be at least twice the material thickness
What are some potential pitfalls of welding stainless steel?
Mixing carbon steel and stainless steel welding consumables
Grinding welds with disc that was previously used on carbon or galvanized steel
What happens with a power brake ?
Requires more force also know as tonnage therefore capacities decrease
When using bottoming or 90 v dies to bend angles what happens ?
Less pressure is required to complete bend fewer scars and scratches and acute angles can be bent
What should be placed on the bottom die’s to prevent contamination?
Protective cover
Neoprene, PE, rubber dies can be used to help form various angles
What should the opening of your bottom die’s be ?
Atleast 8 times the material thickness
Is weldability high for martensitic and ferritic metals ?
Usally low for both
What joint is not recommends for use on stainless steel and why ?
Lap joint
Retains food
What should the tungsten protrude for each type of weld ?
1/4” maximum for fillet welds
3/16” maximum for butt welds
1/8” maximum for outside corner welds
What type of tungsten should be used on stainless steel ?
1/16” 1% yellow thoriated or 2% red theoriated, pure
What should the flow meter be set to ?
A general rule is 20cfh for sheet metal projects
Should the filler rod match your base metal ?
Yes
Does stainless steel have a low thermal conductivity?
Yes
Can grain grow that occurs during welding ferritic stainless be corrected ?
No
What is the reasonable tip size for spot welds ?
1/8” plus 2 metal thickness
What angle should you hold the angle grinder at ?
10 degrees to the metal surface
When close tolerances are required what should be done ?
Use a cross grinding technique
What else can be used besides grinders to grind and clean welds ?
Die grinders
Belt sanders
What is pickiling ?
Uses an acid or mixture of acids to remove scale product in hot Tempature settings
What is passivation ?
A process used to remove any free iron from stainless steel. Uses nitric acid
What is degreasing ?
Removing grease from the surface of the stainless steel
Why is it not recommended to soft solder stainless steels together ?
Joints may be weak
How should full sized stainless steel sheets be stored prior to fab ?
Upright
What should be done before you bend any peices of stainless steel after shearing ?
Deburr all edges
In which series do austenitic steels belong to ?
300 series
When tig welding aluminum what is the first key step for proper welding technique ?
Puddle control
What 2 ways can you cut aluminum?
By hand or by using Beverly shear
What does harmonica sound from a bandsaw mean ?
Blade tension is too low or the distance between other blade guides is too wide
What does Hugh pitched squealing mean ?
Warns of problems with chip formation
When breaking and forming heavy gauge alluminum what works best?
A press brake
How far does the supper jaw need to move back ?
Atleast 3 metal thickness to prevent the brake from pinching the material
When forming soft material what should be done ?
You are better off to make a series of soft brakes rather then a single heavy brake space light kinks 1/8”
What is the recommended female bottum die opening for 1/2” and over 1/2”?
Anything up to 1/2” should be 8 times the material thickness while anything over should be 10 time material thickness
When welding aluminum what type of current do we use ?
Ac
When welding aluminum what are the best tungsten choices ?
3/32” diameter with 2% cerium or 2% thorium, ewp-green also known as pure, ewz- brown ewc-orange
What Tempature does the oxide layer for aluminum melt at ?
3200 while aluminum melts at 1200
Should you use a balled end electrode for aluminum ?
Yes
What are 3 functions of high frequency current ?
Arc stabilization-recognition of positive half of ac
Arc initiation- initation is the non touch start
Gas ionization - aids in starting and promoting the cleaning action of the surface oxide
How does a flow meter read ?
Cubic feet per hour or liters per minute
How should you grind your tungsten’s ?
Longitudinal
What should I’m the inside diameter of the gas cup be ?
Atleast 3 times the tungsten diameter
What amperage can an air cooled torch go to ?
200 amps
Can water cooled torches go higher than air cooled ?
Yes
What is the proper torch angle ?
15 to 20 degrees
When tig welding what method should be used ?
Push
What does aluminum act as ?
A heat sink
What is the most common type of inadequate gas flow ?
Tungsten is immediately consumed and is deposited into weld puddle
What does work like and the half plan for round openings represent ?
Partial plan view shows the exact send distance that the element line moves when viewed from the top
Why is it better to make proper round template before starting to brake form an aluminum square to round ?
Shakeong is easier to control which makes taking it up easier
When welding 1/8” aluminum what type of tungsten should be used ?
EWZ-white
When developing a centered one way square to round what is the minimum plan view required ?
Half pattern while an on center would only need quarter plan
How far should your half plan view be drawn from the edge of the material ?
At least 1inch
How should you label the plan view ?
Label rectangular openings begins with top seam as a and continue to label each point clockwise ending with d
Label round opening 1-7 clockwise
Do you need a diagram of true lengths ?
Yes
How do you tell if a square to round is an outside or inside pattern ?
If the pattern goes abcd its inside of its dcba it is outside
For an elbow seam to pass over a groove seam how far do you need to notch ?
1 and 1/2” times the groove seam
What is formula for collar stretch out ?
Pie(d)+seam allowance
What is the allowance for an elbow seam ?
1/8”
What are diffrent ways for forming a square to round?
A blow horn
Brake
Power brake
When a grooved seam is complete how many metal thickness are there ?
4
Before completing the grove seam you should what ?
Use your hand grooved and riveting hammer to lock both ends of the seam partially
To form an elbow seam what machine should be used ?
The rotary elbow machine
When should you use more than 12 element points to layout triangulated pattern ?
For diameters over 12”
When folding allowances for a grooved seam you should what ?
Fold slightly less than the nominal size
What is allowance for small end ?
7mt
What name is the 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 gtaw more hazardous than any other welding procedure?
No
Is gtaw more hazardous than any other welding procedure?
No
What four main safety precautions should be taken in respect to prior and during the gtaw?
Electrical hazards
Eye protection
Protective clothing
Ventalation
What should be checked prior to welding proven electrical shock ?
Check all connections to ensure they are properly made to avoid the possibilynof electrical shocks
Mild steel has a 50% larger expansion rate compared to stainless steel?
False
Which procedure is quickest to weld stainless steel ?
GMAW
How often should we check all current carrying components required for gtaw ?
Regularly
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 have to be grounded ?
Yes
What should be done to all electrical connections and insulation on the electrode holder and handle ?
Ensure all electrical connections and insulation on the electrode holder (torch) handles and cables are in good condition
How do we know what size torch (electrode holder) needs to be used ?
Must be large enough to handle smoking of current used without overheating
What should be checked for on a water cooled torch head ?
Check all connections for leaks
List 3 things required of the work leads prior to using them for the welding process ?
Good conditioned
Large enough to handle current
Firmly connected to the work to prevent accidental arcing
3 saftey items that must be considered regarding hoses or cables in the work space when welding ?
Protected from hot materials or falling objects
Hung up and out of way when not in use
Leave work area clear of obstacles and possible tripping hazzourds
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 when welding ?
Perspiration can cause gloves to become conductors.
What needs to be done if you 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 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’s comfortable but not lighter than what is recomeneded
What should other people present in the welding area have on for eye protection ?
Wear no. 2 shade flash glasses or goggles
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 you be careful to also protect from bright light ?
Back of kneck and ears
When should we be using ear protection when welding ?
When welding in area with high noise levels
Outlines acceptable noise levels in a working environment ?
Provincial occupational health and safety standards
What type and color of clothing is preferred when welding ?
Dark coloured tightly woven clothing is preferred
What can be the result of wearing a light color of clothing that can reflect light when welding ?
More reflective and may cause burns to eyes even when a helmet is worn
Why should synthetic clothing be avoided when welding ?
Tend to flash (burn rapidly )
What are 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 you collar buttoned and your pockets and cuffs covered when welding ?
Prevent the entry of sparks
What should never be in pockets when welding ?
Matches
Lighters
What type of glove is required for GTAW welding?
Gauntlet gloves of an approved type to protect your wrist and lower arms
Why must we take caution over useing a TIG type welding glove opposed to a general purpose type welding glove ?
Don’t offer the same level of protection
What must a welder have readily available for fire prevention ?
Suitable fire extinguisher
What type of material should be removed or protected when welding in a specific area ?
Any flammable materials
What are four reason it’s mandatory to have local ventilation when TIG welding
Metals that have paint plating or other materials on surface near weld zone produce toxic fumes when heated
Argon or helium displaces air resulting in a deficiency of oxygen that could cause asphyxiation
GTAW produces much higher levels of light than SMAW processes. Oxygen and ultraviolet light produce toxic ozone gas
Welding on some metals can produce posinous gases
Why must we use extreme caution when welding metals containing zinc, cadmium, lead and beryllium ?
Fumes from these metals can be toxic
Why is it important to have the exhaust ventilation serval 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 ?
Eliminate the possibility of interchanging regulators to cylinders
Why is it important on how we store liquid and gas cylinders ?
Prevent incorrect use of gasses
What 2 important pieces of information must be attached to every cylinder containing liquids or gases used for welding ?
Identify the gas it is
Whimis symbol attached
Where are two locations that we can store gas and liquid cylinders ?
Outdoors or in well vented 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 in place
Outlet cap or plugs replaced
What 4 things are protected from atmospheric contamination by the gaseous shield in tig welding ?
Elected
Arc
Puddle
Adjacent heated area of the work peice
Do we always need to use filler rod when tig welding ?
No
Why was tog welding originally developed ?
To weld corrosion resistant and hard to weld materials such as aluminum and magnesium
What delivers the heat between the electrode and the work peice ?
The arc
Where would u add filler rod when tig welding?
To the puddle
How is filler rod inserted into the welding metals containing puddle when heated ?
It’s added separately either manually or automatically
What 10 metals can be welded by tig welding
Aluminum
Magnesium
Stainless
Carbon steel
Titanium
Copper
Copper alloys
Nickle
Nickle alloys
Low alloy steels
When would tig welding be the preferred welding process ?
When highest possible welds are required for the more critical weld applications
Some advantages of tig welding?
Ability to weld most metals
High quality welds
Heat source and filler metal can be controlled separately
No weld splatter
Don’t always need fill metal
What are some disadvantages of tig welding?
Slow
Time consuming so increased cost
Expensive gas shielding
The gas used has asphyxiation hazzard
Can’t be done outside because of gas shielding
List four types of GTAW power sources ?
Transformers
Transformer/rectifiers
Generators
Inverter type
Which gtaw power source is best suited and most commonly used in our industry ?
Transformer / rectifiers designed for gtaw
Which type of current is 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 gtaw workstations what restricts the maximum amount of current that will be delivered to the work peice ?
Amperage adjustment control
What 3 things are controlled by the remote control unit attached to the torch handle ?
Main conductor
Shielding gas flow
Amperage
Whst 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 ?
Power cable on air cooled torch is heavier than that used in the water cooled torch assembly
Why is the one torch power cables thicker than the others ?
Water cooled torch assembly can maintain cooler temps
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 regards to the electrode what is the advantage of using 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 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 ?
Allows u to adjust the head angle for your comfort and better joint access
What is the most common torch head angle used in GTAW ?
120 degrees
List the components of the torch head?
Collet, collet body , torch cap , electrode , gas nozzle
What are 3 functions of the torch cap ?
Prevent 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 the body
What are 5 components that make up an air cooled and or water cooled torch body ?
Handle
Means of conveying shielding gas seal between
Collet body connections
Metal body to transfer power from cable to collet body
Cooling lines (water cooled type)
What three things are normally included in the torch body ?
Cables
Hoses
Machine connectors
What are three functions of the collet body ?
Holds the electrode collet to position the electrode in the torch
Establishes electrical contact between torch body and electrode collet
Directs shielding gas to the gas nozzle
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 collet pushed into the collet body resulting in tightening around the electrode ?
By tighting the back cap
What are most collets made from ?
Copper alloy
What is the result of using mismatched collet bodies and collets ?
Damage to the collet occurs and the electrode cannot be held in position
What is the function of the gas nozzle ?
Direct shielding gas into the weld zone
What type of nozzle is the most common and why ?
Ceramic type because it’s the least costly
What is a major disadvantage of using a ceramic type nozzle ?
They become brittle after repeated use and cause chipping and uneven gas flow
What are 2 considerations which 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 nozzle ?
Give a better shielding action at lower gas flow rates
What metals are normally welded using a larger nozzle ?
Metals that oxidize readily at elevated temperatures
List 3 other types of nozzles available but are not commonly used in the sheet metal industry ?
Alumina gas nozzle
Fused quartz nozzles
Sleeve type metal nozzles of the slip on style
What can result in not keeping the nozzle clean ?
Build up resulting in turbulence in the gas flow and contamination of the weld puddle if build up falls in 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 using a gas lens will the distance between the work and nozzle increase or decrease ?
Increase nozzle to work distances
What can cause a gas lens to disrupt gas flow?
Fine spatter or other contaminants
What is crucial for f the use of a work lead ?
Clean contact surfaces and make good electrical contact with the work peice
What defines an electrode ?
Picks up or emits electrons in a electrical circuit
Which type of electrode is used in the GTAW process?
A non-consumable tungsten electrode
What is the purpose of an electrode(tungsten) when used in the gtaw process?
Transfer electrical current across the arc between the tungsten and the work
Why is the tungsten used as an electrode in gtaw process ?
High refractory metal with melting point of 3410 degrees Celsius and 6170 degrees Fahrenheit which is the highest melting point of all metals
How are the size of tungsten’s 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 a color code system to identify each electrode
What would u use to help heat distortion when welding ?
Cooper chill plates
What type of file is a CAD file for the plasma table ?
DXF
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’s 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, gardening and embrittlement in the weld
List 3 gasses that are normally used in 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 in argon replacing oxygen in the work area?
You could be asphyxiated
List 3 applications where helium would be used for gtaw welding ?
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
20%hellium
Where would an argon helium mixture be a good choice for shielding gas ?
Stainless steel and non ferrous metals Automatic high
What is the main disadvantage of using an argon helium mixture ?
Cost
What are two ways that shielding gasses are stored in ?
High pressure cylinder
Bulk liquid systems
How open should gas cylinders valves be when in use ?
Valves should be opened fully
3 main functions of a gas regulator ?
Reduce source pressure to working pressure
Maintain a constant delivery pressure regardless of variations at the source end
Deliver gas at any desired pressure within its rated capacity
What two ranges are regulators designed to work within ?
Pressures
Volumes
What do regulators control ?
Pressure not flow rates
What regulates the flow rate of a shielding gas ?
20 flow meters
How are flow meters calibrated to indicate ?
Liters per minute or cubic feet per hour
Elegant is the difference between a regulator and flowmeter in terms of what they indicate ?
Flowmeter indicate volume flow
Regulators indicate pressure
Why are flow meters designed and calibrated for specific gasses ?
Because Thier densities are diffrent
On a combination regulator/flowmeter why is the regulator pre set to a specific pressure ?
So that it is compatible with the flowmeter
Why are gauges on a gauge style combination regulator / flowmeter not as accurate as a flow tube style flow meter ?
Because they operate on pressure converted into volume
What type of hose should be used for transferring shielding gasses?
Hide designed for transferring shielding gases
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
Four ways filler materials can be available for gtaw welding ?
Straight rod
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
(1/16” to 1/4”)
How are diffrent filler rods identified ?
Attached tag or stamped impression
What must the filler rod match in relation to the base metal being welded ?
Match or exceed the base metal properties
In carbon steel what does the E R 70 S 2 represent in ER70S-2
E=electrode
R= rod
70=minimum tensile strength in pounds per square inch
S= solid wire
2= manufactured chemical analysis
In stainless steel ER347 what does the E R 347 mean ?
E =elctrode
R=rod Flattened rods
347= grade of stainless
Under normal circumstances die’s filler rod require any specific prep prooor to welding?
No
Where should the hot end of filler rod be located during welding ?
Protected by the inert shielding gas during the welding to reduce atmospheric contamination
Where should filler rod be stored when not being used ?
Remain in they’re containers until required for service
What is amperage ?
Measure of the number of electrons
What is voltage ?
The pressure needed to push the amperage
What are the 2 methods of preparing electrodes ?
Grinding
Electrical arc
What does a concave area in the weld mean ?
Sugaring effect (to hot)
What is the cause of incomplete penetration when welding ?
Arc length to low
Current setting to low
What causes a lack of fusion ?
Arc to long
Current setting to low
Incorrect fit up and prep
What is the cause of porosity with in the weld bead ?
Inadequate gas shielding
Air drafts
Dirty materials
Moisture
Contamination
What does excessive gas flow create ?
Venturi effect (increase in velocity decrease in pressure )
