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TIG Welding 101

Safety Considerations

  • Keep a fire extinguisher beside you

  • The biggest dangers come from our complacency and not being totally aware of what we are doing. Don't take shortcuts that compromise safety.

  • Point out the following safety equipment:

    • Fire extinguisher

      • At each doorway

    • Fire exits

    • First aid kits located at front desk

  • Metal Shop Safety Guidelines

    • Wear appropriate clothing:

      • Clothes should be made out of natural fibers such as cotton or wool. Do not wear synthetics as they melt to the skin

      • Full length pants which fit over your boots – to stop hot metal/sparks from getting into your footwear

      • Wear a long sleeved shirt and pants without cuffs and have your pant legs cover your shoes so sparks can't drop into your footwear

      • Wear leather boots, CSA approved boots are best, no sandals or open footwear (green shield)

      • Wear leather gloves (demonstrate different types of gloves)

      • Long hair, drawstrings and shirt tails/sleeves tucked in/ tied back,

      • Safety glasses at all times in shop, hearing protection recommended

      • Avoid wearing jewelry

    • Main causes of injury are:

      • Sharp metal edges

      • Sparks

      • Heat and flame

      • Arc Flash

      • Electric Shock

      • Welding Gases

      • Fumes

    • Metal safety:

      • Hold it like it's glass (sharp edges)

      • May be very hot, always check before you grab or wear gloves

    • Electricity:

      • Electric shock can occur when arc welding. This usually happens when the current passes from the electrode through the welder to the piece being welded and through contact with poorly maintained electrical cables

      • Don't set handle on table - hang from cart

      • Primary electric shock is much more hazardous because the voltage is much higher than the secondary or welding voltage.

      • AC is 2 to 3 times more dangerous than DC welding.

      • Inspect your equipment to make sure it has been properly maintained.

      • Wear proper PPE (personal protective equipment) to insulate yourself from electrical hazards, dry gloves and rubber soled boots.

      • NEVER touch ground & tip at the same time (ground is kept up at the front desk)

      • MIG (Metal Inert Gases) = cable is hooked up to (+) port on box

      • DCEP (Direct Current Electrode Positive) (electrode = welding gun)

      • Don't weld in damp conditions

    • Gas:

      • Never move without cap!

    • Fire Hazards:

      • No flammable items/substances in a welding area, e.g. no wood dust or stains, etc. (wood welding jigs are ok)

    • UV light:

      • Don't wear white (reflects under mask = neck burn)

      • Cover all skin (to prevent sunburns)

      • Always use red UV shield to protect others

      • Warn others before you start, e.g. "Arc up!"

      • Masks:

      • Auto-tint = when it sparks, vision darkens

      • Blocks UV light

      • "DIN" = can adjust auto-tint setting

      • 9 = brightest

      • 6 = plasma cutting

      • How to adjust knobs to head

    • Air extraction:

      • Can wear a mask, but welding mask may not fit over it

      • Open door, turn on overhead extraction

      • Aluminum is worst, steel not as bad

      • Rust & paint on metal pose dangers as fumes

      • Wear a mask if you grind off (dust)

    • Welding Fumes

      • When welding the melting metal oxidizes and produce gases such as carbon monoxide, carbon dioxide, oxides of nitrogen and ozone. We also use gases such as argon and carbon dioxide in the welding process to shield the weld and prevent oxidation.

      • Metals contain many alloys that can release contaminants into the atmosphere during the welding process.

      • A coating on metal which could emit harmful contaminants (such as lead, chromium, organic materials, or toxic combustion products) must be removed from the base metal, whenever practicable, before welding or cutting begins

      • Different metals have different fumes

        • Mild Steel

          • safe

        • Aluminum

          • A little toxic

        • Stainless Steel

          • Chromium likes to leave the base material and is very toxic

          • Need respirator

        • Galvanized Steel

          • No-go

          • Very toxic

          • Have to clean the plating off of it to weld

    • Confined Spaces

      • Always test for oxygen levels before entering a confined space. Any reading lower than 19.5% (at sea level is said to be deficient). Use fans to ventilate the space or use a welding helmet with an air line bringing in an outside source of fresh air.

      • NOTE: Inert gases like argon are heavy and will displace oxygen in a confined space. If you see someone unconscious in a confined space DO NOT ENTER the space unless you a wearing a self contained breathing apparatus. In January 2003 four workers at Westminster Marine Services died. Three of them were would be rescuers.



Machine Setup


TIG (Tungsten Inert Gas)

    • TIG stands for Tungsten Inert Gas and is technically called Gas Tungsten Arc Welding or GTAW. The process uses a non-consumable tungsten electrode that delivers the current to the welding arc. The tungsten and weld puddle are protected and cooled with an inert gas, typically argon.

    • Compared to MIG (Metal inert gas) welding or metal active gas (MAG) welding, is a welding process in which an electric arc forms between a consumable wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to melt and join.

Gases

    • Don't open too fast

    • Watch gauges: flow (cfm) & pressure (psi)

      • Gas flow is 15 - 20 cfh (cubic feet per minute)  / 7 - 10 L/min

    • 100% Argon (at MakerLabs)

      • Argon heavier than air - so to sinks

      • TIG can use different gases (helium or argon or mix) - almost always 100% argon

Machine

    • Electricity through the base material and electrode

      • DC

        • Electrode negative

        • For steel / stainless steel

      • AC

        • Alternating power

        • For aluminum

    • Amperage

      • Mild Steel 1/8“ : 120 – 130 Amps

      • Aluminum 1/8” : 150 Amps *** AC power

    • Pulse Control

      • Pulses per second – pulsates the power drawn between a low and high setting

        • Can control heat

        • Useful in overhead and vertical welding

        • Turn it off unless you have reason to use it

    • For AC only

      • Arc balance  

        • Experimentally found

        • Where it spends the most time (negative or positive electrode)

        • 75 (average)– is percentage of balance below  

      • Frequency

        • 120 Hz is good  

        • Useful range is 60 Hz – 120 Hz

        • Can change for puddle control


    Torch

    • How to assemble

    • Electrode diameter designate the

      • Cap

        • It is ceramic and can break when dropped

      • Cullet body

      • Collet

    • Torch cap

      • Houses the electrode

      • Can be interchanged to get in smaller places

    • Nozzle diameter

      • The inside nozzle diameter should be 3 times the electrode diameter

    • Electrode

      • Stick Out

        • How much it sticks out past the cap

        • 1 - 2 times the electrode diameter

    • Assembly steps

      • Put cap on collet body

      • Then screw it on

      • Twist the cap and torch cap simultaneously to tighten

      • Rod can go in at any point - be aware it’s brittle


Cable

    • Both gun & gas run through

    • If it loops, do not pull on them - will kink wire

    • Expensive to replace

    • Treat carefully - don't step on it


    Filler Rod

    • What fills the gap

    • Different types have small differences (ie. anodizing afterwards)

    • Manually feed it into the puddle

    • Types of Filler Rod

      • For mild steel: ER70S-6 3/32” x 36”

      • For 6061-T6 Aluminum: ER4043 3/32” x 36”

      • Different types have small differences (ie. anodizing afterwards)

    • Bring your own filler rod at MakerLabs

    Electrode

    • Electrode Composites

      • Designed by E (electrode) T (tungsten) P (pure)

      • Pure tungsten

        • Lower melting temperature

      • Ceriated 2% tungsten (EWCe-2)

        • E (electrode) W ( tungsten) Ce-2 (2%)

        • Best to use

      • Some older tungsten composites are radioactive

    • Diameters

      • Large diameter = more amperage it can handle

      • Common diameters

        • 3/32”

          • Suitable for 1/8 “ - 1/4” base material

        • 1/16”

        • 1/8 "

    • End Types  

      • The end of the electrode needs to be sharpened a specific way

      • DC - sharpened to a point

        • When welding steel, length of taper tip should be to 2 to 2.5 of the diameter

      • AC - rounded over

        • The diameter of the end should not be 1.5 times the diameter of the electrode

    • Very brittle, can break easily

    • Everytime it touches the puddle, it needs to be re-sharpened

    • Bring your own electrode at MakerLabs


Table setup

    • Use magnetic squares to get 90-deg welds, etc.


Types of Welds


Welding Technique

  • Cleaner metal = better weld

    • All metals have to me shiny clean

    • Any oxide on the material will melt before the base material and interfere with the weld - contamination of weld / lack of fusion ( puriosity, graying )    

    • Clean with wire brush or scotch pad

    • Note Aluminum oxidizes within minutes and steel within days

  • TIG = adding material, needs somewhere to go

    • Grind 45-deg corner on each piece to make a valley

  • Torch is approximately 15 - 20 degrees from vertical

  • Distance from electrode to base material (tip to work distance - TTW) is approximately 1.5 times the electrode diameter

    • If the electrode touches the base material, it needs to be re-sharpened

  • Anchor arms to keep movement steady and to feel when you move

  • Do a "tack weld” first

    • on both sides

    • so weld doesn't pull over

    • add one bead where you plan to end actual weld as well - cleaner ending

  • Then "stitch" back and forth between surfaces as you push/pull the puddle

  • Keep puddle the same size and moving

    • too slow = puddle may melt thru

    • too fast = only sits on top, like hot glue

    • want a consistent sizzling bacon sound - no popping or sputtering

  • Filler Rod feeding techniques

    • Effects the freeze points   

    • Continuous

    • Dab

      • Creates a wavy finish

  • If you are doing a long weld, start from an uncomfortable position and move towards a comfortable position

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