Welding Flashcards by KVN 145

What does DCEN look like

-Negative is on Electrode
-Positive is on metal plate
-Deeper penetration because plate is hotter

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What does DCEP stand for?

-Electrode Positive
-Positive is on Electrode
-Negative is on Metal plate
-This has a shallower penetration

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Where are these more commonly used? : DCEN DCEP?

DCEN = TIG (Deeper penetration)
DCEP = SMAW (Shallow penetration

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Explain what happens with AC polarity and what is the penetration look like?

-polarity goes up and down between 0. When it goes up, it cleans. When it comes down, it penetrates
-Used on aluminum because it had oxide on its surface. This will clean surface

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What type of polarity does DCEN have?

Straight Polarity

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Why does DCEN have a deeper penetration?

It’s a straight Polarity and it concentrates the heat in a joint area

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What type of polarity does DCEP have?

Reverse Polarity

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Why does DCEP have a shallower penetration?

Because it focuses the heart at the electrode

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What DC is a Reverse Polarity?

DCEP
Electrode is positive

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Does Reverse Polarity half cycle have a lessor magnitude(size, strength)than straight Polarity? True or False? Explain.

True. Because the electricity has a hard time penetration the metal after

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Why would people prefer using GTAW vs stick welding?

-Cleaner Weld
-More Precise
-Thinner Metal
-Food grade
-Stainless steel

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Can you use GTAW on structural type work?

-Yes you can but this type of welding is much more slower process.
-Too expensive because you’re using gas

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When using GTAW, what is the polarity usually? DCEN, DCEP or AC?

-Most commonly DCEN
-Deeper penetration
-Tungsten is cooler
-

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When do you usually get a Primary Current and High Frequency in your weld? What polarity is it and what are the numbers?

Primary Current =60hz
High Frequency=16,000hz

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What is happening in the 60hz Primary Current and High Frequency

60hz= is how long it takes for the polarities to change
16,000hz= small electricity that helps bridge arc connection

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What type of polarity do I need to use if I want a deeper penetration on my work piece?

Straight Polarity
DCEN

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Which wave has a Deeper Penetration and Greater at Cleaning?

-Deeper Penetration is on the left (the wave is longer on the negative side)

-Greater at Cleaning is on the right side (the wave last longer on top of the material)

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What is the name of this meter?

Flowmeter

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What type of meter is this?

Gauge type flowmeter

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What is set in place here as a safety precaution and explain.

-Rupture Disc
-If pressure builds up too high in cylinder, Rupture Disc will break to release pressure safely
-Prevents the cylinder from exploding

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What do these stand for?

E:Electrode
W:What electrode it is primarily (Tungsten)
Th: Electrode is alloyed with Thorium (tungsten)
2: 2% Thorium. This number tells you how much percentage of metal is in the rod

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Does the shape and size of the Electrode affect the Bead Width? Why?

-Yes
-Thicker/Larger Electrode carry more current= wider, deeper bead
-Pointed or Thin Electrodes concentrate heat = narrow bead

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What is the correct way of grinding a Tungsten Electrode? Longitudal Grind or Circumferential Grind?

Longitudal Grind (Long point)

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What’s the difference between GTAW vs SMAW rods?

GTAW: Is the Tungsten rod for the arch. Not a consumable

SMAW: Is a consumable rod that adds metal to work piece

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How do you read this and is this SMAW or GTAW?

E: Electrode R: Rod 49:Tensile Strength 49k psi ( how much you can pull the metal apart) S: Solid (rod) X: Shows what elements are in the electrode

How can you tell in these 2 examples which metal is Solid or Composite is? ER70S-XN HZ E70C-XYN HZ

S: SOLID -usually the Tungsten in TIG (used for electrical arch) and one solid metal only C: Composit -usually the flux coating from a consumable rod and mixed with multiple meterial (flux,metal core)

What are these?

Shapes of rod consumable inserts

What are the difference between Argon and Helium penetrations?

Argon - more of a cone shape Helium - nipple shape cone

What are the disadvantages of using these shielding gases? Argon Helium Nitrogen Hydrogen

Argon - asphyxiation in confined spaces - require special ventilation - undercuts Helium -Expensive -Higher flow rate because it rises -Arc less stable Nitrogen -Sends to oxidize and deteriorate tungsten -Contaminate weld Hydrogen -Highly flammable -Special ventilation -Expensive

What are these classifications?

Ce- Cerium (🧡) P- Pure Tungsten (💚) La- Lanthanum (🖤) Th- Thorium 1(🟡), 2(♥️) Zr -Zirconium (🟤) G- General classification (🩶)

Which of these tips would best be used on AC and DC?

AC - Pencil/Bulb point -Easier Cleaning DC - Very sharp point -Concentrates heat better focuses arc

Which wave is better for TIG and why?: AC Square wave Conventional AC Sine Wave

-Square wave -More stable arc -Easier to control -Cleaner oxide removal (aluminum) -More heat in workpiece without blowing through

If using these metals below, what DC polarity and Shielding gas do they all use? Bonus, what nossle number size #? Ce Th 1,2 La

-DCEN (Straight Polarity l) -Argon - Nossle size #6

How much of a cone should your Conical Electrode be for penetration?

2 or 6 X D (Diameter of rod) = ?

What is the best angle for your tungsten electrode and what is the maximum?

-90Deg (best) -30Deg (max)

What are the effects of a Short Arc vs a Long Arc? Describe

Short arc: deeper penetration (closer to the metal) Long Arc: Shallower penetration (further from metal)

What is the proper way of Scratch Starting a Tungsten Weld?

1. Swing down 2. Make contact 3. Draw an arc (get your arc and control it at 90deg from workpiece)

How do you perform a High Frequency start?

1.start your rod almost parallel with your workpiece 2. Bring it up 90deg and maintain arc

How do you perform a Lift Start with Tungsten Welding?

1. 90 def from work piece 2.Bring lower 3.make contact (hold 2-3sec) 4 Lift (do not strike like a match)

What are the Filler Rod, Sight Position and Torch Inclination when performing TIG welding?

-Rod is 20deg -Torch is 90deg-70deg (max) -Sight position is from the Left hand side (pull towards you)

What are the Torch Position for Lap Joints during TIG welding?

-Same 20 deg rod, 90-70deg (max) Torch -rod= 10 deg away parallely -Torch- 20deg parallel away from parallel

Dip vs Continuous Feeds. What are the difference between them?

Continuous = filler Rod is steadily fed while moving torch Dip Feed = filler Rod is tapped/dipped in weld pool

What is the purpose of Continuous vs Dip Feed in TIG?

Continuous = good for long runs and consistent weld bead Dip Feed = small welds, tricky spots, thin metal

From a visual stand point ,what does a Continuous vs Dip Feed weld look like (1 Pass)?

Continuous: smooth bead Dip: Ripple effects

What are the advantages and Disadvantages of Scratch Start?

Pros: Simple Cons : Risk of contamination (metal touching tip)

What are the advantages and Disadvantages of High Frequency Start?

Pros:Clean Cons: Require electronics (machine needs HF setting)

What are the advantages and Disadvantages of Lift Start?

Pros: Cleanish without HF Cons: Slower

In an Aluminum Extrusion stamp, what is the information you see? 6060H HA16261

6060H: Grade/Alloy HA16261:Batch # 6060=Med Strength H= Work Hardened

Match the Current polarities DCEN,DCEP,AC in this picture and explain why?

Top: DCEP, bead looks okay because heat is focused on electrode Middle: DCEN, bad weld because heat is focused more on metal piece Bottom: AC, good bead because it's alternating current which switches polarity and creating a good oxide cleaning effect

When welding in Stainless Steel, what does the term "Sugaring" mean and what is the quality of the weld at this point?

-Sugaring means Oxidation -Bad quality weld (melt-through)

In Stainless steel, what happens if you see Concavity effect on your bead weld?

Bad sign. It means you welded through metal

What is a Pre Shaped Backing Bar?

-Metal piece placed behind w joint for welding -Helps form proper weld root -Keeps metal from falling through

On a Butt Joint, how far apart should your Tacks be when you have a 1/8" overlap?

2" Tack Gaps

When TIG welding on a Stainless Steel metal, how would you sharpen or prep your TiG tip?

Longitudal Grind

What is Autogenous Tig Welding?

-No use of wire for feeding and creating the weld -Tungsten will heat up and melt metal pieces together Benefits: -Thin metal -Stainless steel -Nothing to consume (cheaper) -More control

What is the High Frequency radius (leakage) that will affect other equipment?

15m radius

What cleaning solvent (that contained chlorine) will react to UV radiation to create?:

Phosgene gas (deadly gas)

What is the Minimum and Recommended shade from intense UV and infrared rays?

Min: 9 Recommended: 10+

GTAW welding machines are what type?

CC = Constant Current

For mild steel and Stainless welding high frequency Start/Continuous should be set to: Start Or Continuous

Start

What does "Post Flow" do?

-Protects electrode and weld from atmospheric contamination -Do not back off your torch right away

What type of metal would you be welding at High Frequency and Continuous mode?

Aluminun

What does the foot pedal primarily used for?

Provide Variable Amperage Control

Torch Mounted and Foot Pedal are the two of the most common means of remote control of the Current Flow?

True

What are the reasons for these types of tips? Explain each one -Sharp Pointed -Conical Tapered Circumferential Grind -Square End -Balled End

-Sharp Pointed -Conical Tapered Circumferential Grind -Square End -Balled End

How do you read this? And is this AWS or CAS/CSA? ER 70 S-XNH2

In ER 70 S-XNH2, what does 70 stand for?

70,000psi

In B-G 49 3 A G2, what does A stand for?

Argon gas is required

When converting MPa to Psi, what value do we multiply the MPa by?

145

True or False, O2 and CO2 are good shielding gas because?

False. They would oxidize the electrode and contaminate the weld

Welding Flashcards

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