Tools/TIG/induction

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Some of the tools at the Hackspace are potentially hazardous to use, for these tools members are required to have an induction before they can use them. Inductions provide the most basic information on how to safely and effectively use the simpler functions of the tools, we appreciate that some members may have professional experience on some of these tools and in this case please tell your induction provider and the induction may be very reduced and just cover any risks or procedures specific to rLab. Some tools have multiple levels of induction in order to cover more advanced uses of that tool without making the basic induction take too long, higher induction levels will introduce some of the more advanced features of the tools but as with all inductions are only intended to provide basic information on the capabilities of the tools and how to use them safely. Some members of rLab may be willing to offer more detailed tuition beyond basic induction level or offer guided practice sessions in exchange for beer money or assistance on their own projects.

For all tools you are only required to take level-1 induction before use, after that you may perform any task that you feel confident you can do safely, higher levels of induction may be useful to you in performing more advanced operations but are not required before doing tasks covered in them so long as you're confident of your ability to handle those tasks without risk to yourself, others, or the tool.

PLEASE NOTE : All induction providers are volunteers who are providing inductions to the best of their ability but are NOT qualified instructors. Inductions are provided on a best-effort basis but you and you alone are responsible for your safety while using the tools and for satisfying yourself that you can operate the tools safely. There are professional training courses available from various providers in Reading and the surrounding area if you feel they are appropriate for the level of work you intend to undertake. Reading these notes is NOT a substitute for an in-person induction.

Note for wiki editors : Please do not edit induction pages unless you are one of of the people that gives that induction

TIG welder induction (TIG Mode) Level 1

Level 1 induction in intended to cover the basics of how to use the TIG welder, it covers basic safety information and how to use the welder effectively on mild and stainless steel in positions 1G and 2G/F. People undertaking TIG induction need to have overalls or other non-flammable clothing that covers all exposed skin except for head and hands. Wear stout shoes or boots, no open shoes allowed. If you have any metal you'd like to practice on then please bring it with you so long as it's plain steel with no galvanized coating or paint but if you don't have any then we usually have suitable scrap around to practice on. There's no charge specifically for the level 1 induction but normal welder usage charges apply, you should expect it to cost around £10 for the induction and a bit more if you spend some time practicing afterwards which is strongly recommended. This induction may takes up to 3 hours depending on skill. Please remember that what you might have seen on youtube/instagram is people showing off their very best welds that may have taken years of practice and multiple attempts to achieve, you will NOT be getting results like that after just an induction. The goal for induction is to be able to use the TIG welding without being a danger to yourself or others, it's not even to achieve structurally sound welds, TIG welding is a high-skilled process and it takes a minimum of hundreds of hours of practice to get photograph-worthy results like that.

For people who've not welded before For people who can already MIG weld
For people who've not welded before the full technique and safety briefing is required
Topic Detailed contents
Types of welding available
  • MMA - Fast, thick, dirty, good outdoors, medium-high skilled
  • MIG - Fast, medium thickness, relatively clean, low-skill requirement
  • TIG - Slow, Neat, special materials, super-clean, high-skilled
  • Forge - V.V.Slow, good for big flat welds, high-skilled
  • Spot - Tiny spot welds for joining plate, low-skilled
  • Gas - Gas welding is most similar to TIG but we don't have it at rLab for safety reasons
Safety
  • Fire hazard
    • Metal sparks and radiant heat/light
    • Clear area of flammable materials, be aware of solvents and vapors
    • Having fire extinguishers handy and what types are suitable
  • Arc-eye hazard to you and people around you
    • Using an auto-darkening welding mask
    • Suitable settings on mask (9-11, 12 maybe - start at 10 and adjust)
      • Testing visors before use
      • Any setting will save your vision, you're just adjusting for best visibility
    • Shouting "Eyes"
  • PPE - Overalls, stout shoes, gloves, mask, dust protection when needed, Cover all exposed skin or you'll regret it!
  • Care with Galvanized steel, risk of metal-fume-fever
  • Gas safety
    • Enclosed spaces
    • Low spaces
    • Fumes
  • Electrical Safety
    • The voltage is low, but you still don't want to touch it
    • Mind what you point the torch at
    • Power cuts off a little after the trigger is released
    • NO RINGS, NO WATCHES!!
    • If something does go wrong, shut off power before anything else
Preparing to weld
  • Check metals are suitable
    • Mild/Stainless steel only at level-1 induction
      • At level-2 aluminium and other metals are covered, TIG can weld almost anything metallic and some things that arn't
    • Beware of galvanized steel
    • Beware of lead-bearing and copper-bearing paints
  • General angle grinder safety
    • Types of disc
    • Inspecting grinder and disc
    • Changing the disc
    • Care of position and cut angle
    • Dust protection, eye protection, gloves
    • DO NOT TWIST in a cut
  • Clean up weld area - be aware of burning paint
  • Clean area for earth clamp
  • Beveling edges to form a path for the bead on butt joints
    • No bevel on thin materials
    • Regular 2/3rds bevel most of the time
    • Beveling from both sides for very thick
For people who can already MIG/MMA weld this can be shorter
Topic Detailed contents
Safety
  • Fire hazard
    • Largely as for MIG/MMA
    • Clear area of flammable materials, be aware of solvents and vapors, especially as solvent cleaning is commonly used for TIG
    • Having fire extinguishers handy and what types are suitable, TIG uses a higher voltage so avoid water type
  • UV Hazard
    • As for MIG/MMA but TIG emits even more UV owing to continuous arc mode
  • Gas safety same as MIG
  • Electrical Safety same as MIG
Preparing to weld
  • Check metals are suitable
    • Mild/Stainless steel only at level-1 induction
      • At level-2 aluminium and other metals are covered, TIG can weld almost anything metallic and some things that arn't
    • Beware of galvanized steel, it's even worse for TIG than MIG
    • Beware of lead-bearing and copper-bearing paints
  • Cleaning must be immaculate, much better than for MIG as TIG gas provides no fluxing action at all
    • Clean up weld area - be aware of burning paint
    • Clean area for earth clamp
    • Beveling joints is same as for MIG/MMA
Topic Detailed contents Rationale
How it works
  • Machine strikes arc between the work and a non-consumable tungsten electrode, melting a pool of metal
    • TIG welding is the most similar welding process to soldering but there's still an important difference. In TIG welding you're melting the base material and allowing it to flow together, not only adding material on top
  • Filler wire is added manually while moving the torch forming a weld bead that joins the metals
  • Gas shields the weld pool and the tungsten from air exposure
  • Earth clamp provides return path
Basic process details
Machine Description
  • Torch
    • Tungsten
    • Cup
    • Gas shroud
    • Collet
    • Back cap
    • Switch
    • Power control
  • Base unit
    • Power source (we'll get into settings later)
    • Power, Control and Gas lines
    • Gas connection
    • Power feed on the back, mention the limits imposed by 13A connection
  • Gas bottle
    • Type of gas and why
    • Basic safety for the Albee bottles
Covering what all the parts are called and do
Preparing to weld (continued)
  • Clean up weld area
    • The complete lack of fluxing action from Argon means TIG is a lot pickier about cleanliness than any other welding technique
    • The weld zone must be immaculately clean
    • Cleaning the weld with solvents
      • Acetone is recommended, pure alcohols like IsoPropanol or Methanol will generally work, Meths or white spirit will not.
      • NEVER Chlorinated solvents like brake cleaner (Phosgene risk)
    • Remove all solvents and cloths when done because of fire risk
    • Avoid even touching the weld zone once it's clean
  • Clean area for earth clamp
Proper preparation is necessary for good welds
Setting up the welder

Start at the tip of the torch and work back....

  • Tungsten
    • Types and their suitability
      • 2% Thoriated (Red Tip) - DC Welding on steels only, radiation danger
      • 2% Lanthanated (Blue Tip) - Universal, can be used on all metals and polarities, recommended for normal use
      • 2% Ceriated (Grey Tip) - DC use on thin materials, excellent arc stability at low powers
      • Others are available for special job but these should cover 99.9% of welds
    • Selecting a suitable diameter (diameter 50%-100% of work-piece thickness, checking chart on welder)
    • Grinding a suitable point, 30 degree point, blunted tip if running higher currents
    • Picking a suitable collet and collet body and fitting them
    • All fittings on the torch are hand-tight only, no tools allowed
  • Torch
    • Picking a gas cup from the table on the welder and fitting it, what the cup numbers mean
    • Using a suitable back cap, access and clearance issues, silicone grease is needed
    • Setting stick-out
    • Power button on torch
      • Option of using pedal control later but for now stick to the button
    • Set power dial to 10 and don't try to adjust while welding
  • Welder
    • Checking correct polarity, making sure earth lead is connected to work
    • Check tightness of connectors, they'll catch fire if they're loose!
    • Plug in welder but don't turn on yet. Directly plug in, never use extension leads
  • Gas
    • Check remaining gas level
    • Setting suitable gas flow rate using the bottle's regulator using the table on the welder, but consider situation of weld

Suitable setup and settings for executing the weld

Configuring the welder

Welder Settings

  • Mode Settings around the outside
    • AC or DC
      • Steel and stainless steel are done DC electrode negative (Straight polarity)
      • Aluminium and other metals with refractory oxides are done AC, that is not covered in level-1 induction
      • DC electrode positive is a thing, but only very rare situations call for it
    • Pulse mode
      • Useful sometimes but details not covered in level-1, leave this turned off
    • Purge - Used to clear air from the lines
    • Power and overheat lights - Duty cycle, 100%@90A, 60%@115A, 20%@200A but max is about 120A on 13A plug
    • Process
      • Lift-TIG - Hard to use, not covered at level-1, only useful if sensitive electronics are nearby
      • HF-TIG - Standard mode, use this
      • Stick - See TIG Welder (Stick mode) Induction, beware that going into stick mode - even momentarily - will cause the electrode to become live at up to 90V with no control from the trigger
    • Trigger
      • 2T - Press and hold to weld, we'll be using this mode
      • 4T - Press and release to start, press and release to stop, good for long welds but has more parameters to set and harder to use, not covered in level-1
  • Parameters set using the middle section. We're using DC (Electrode negative), no pulse, HF-TIG in 2T mode. Back and Forward controls step through the parameters that are relevant to the selected mode
    • Using the chart on top of the welder to pick settings
    • Do not attempt to reduce settings very much to make things easier. Small current reductions may sometimes be needed but if you try to slow down too much the weld will turn to shit and heat affected zone will be huge because you'll be going so slow. You just have to learn to keep up with proper settings.
    • If the chart isn't helping then use the following guidelines. Use all the %age changes that apply to your work, e.g. if you're doing an outside corner on stainless steel then apply both -%10 current for Stainless and -10% current for outside corner for a total of -20% change to current and +45% gas
Basic Current & Gas 40A/mm of material thickness 1L/min per cup number
Inside corner +10% current -20% Gas flow
Outside Corner -10% current +25% Gas flow
Stainless Steel -10% Current +20% Gas flow
    • Preflow - Time in seconds, is used to establish coverage of shield gas before the arc is ignited. How much to use will depend a little on what you're doing but 0.5-1.0 seconds is usually reasonable for steel
    • Hot Start - This is an extra very short pulse of current used to help establish the arc, this is IN ADDITION to the base current, so you don't need very much, 5A-20A is normal
    • Base Current - This is the normal weld current that will be used for the entire weld, check the chart for an initial reasonable setting for your job. Think carefully about this one, it's your biggest factor controlling heat buildup in the weld. If you go too high the weld will overheat, but it'll ALSO overheat if you go too low because you'll have to slow down too much.
    • Downslope - This is how long the welder spends backing the current own gently at the end of the weld, values around 0.5-0.7 seconds are typical for steel but if you're getting "crater" at the end of the weld then a longer period may help. Note that this gentle back-down occurring AFTER the trigger is released means you can't pull away from the weld right away, you have to stay close and let it happen.
    • Post-Flow - This is how long the gas stays running after the arc has stopped in order to keep the weld and especially the tungsten shielded as they cool down. It will depend on how large your weld is, huge welds might need as much as 15 seconds, a small weld with a small electrode might only need 3 seconds. We'll be using 5 seconds as a middle-of-the-road setting but you might need considerably longer on stainless steel. You must keep the torch pointed at the weld throughout the post-flow period and also note that if you press the trigger again during post-flow the arc will re-ignite instantly!
How to set the arc parameters
PPE safety
  • Overalls are required for UV protection
  • We have special TIG gloves that are much lighter and less stiff than normal welding gloves which can be used because TIG doesn't generate very much radiant heat or spatter. These gloves are made of goatskin or pigskin and are specifically reserved for TIG welding and must not be used for anything else
  • Welding masks will protect your face and eyes from the UV light
    • Test the visor before use
    • Change the cover sheets on them if necessary, report it if we're out of properly fitting replacements
    • Depending on the welding current you may want to use shade 9-12 on the welding helmet. All settings will save your vision, you're just adjusting for best visibility. If you're used to MIG/MMA then go one setting darker than you normally would for this current.
  • You may see people online welding without overalls or even without gloves. They can get away with this because of the low-spatter nature of TIG welding. DO NOT DO THIS - They are probably wearing SPF-1000 sunblock and have developed a tolerance over years, they'll still probably wind up getting skin cancer from it! Cover all exposed skin at all times while welding.
Using the right PPE for TIG welding
How to actually execute a weld
  • Proper position of self
    • TIG can be used in all standard positions, but over-head is rare and difficult as there's a tendency for the puddle to fall out onto you.
    • Holding TIG torch in your dominant hand and the filler rod in the other hand
    • Getting a comfortable position, sitting down if possible
    • Lead can be draped over your shoulder if you find that helps to keep the load off the torch
    • Checking the position remains comfortable throughout the range of motion needed for the weld you're about to do
    • TIG requires precise, steady movement, so it's very important to be comfortable and able to move freely while doing it.
  • Proper position of torch, direction of motion
    • Ideally we'd hold the torch perfectly vertical but if we did that we wouldn't be able to see what we were doing or feed in filler rod, so we normally use a push angle of 10-30 degrees. More perpendicular torch position will usually result in a better weld but consider your movement, access, and vision, angles 45 degrees or more WILL NOT WORK PROPERLY.
    • Pull welding with TIG is not a thing, don't try it, but it is sometimes possible to back-track a very short distance (no more than the puddle width) in order to move the puddle around and get full fusion.
    • Correct distance of the tip is only 1x-2x the diameter of the electrode you're using, and needs to be maintained very steadily. Maintaining this distance properly is the single most challenging thing about learning to TIG weld and will have the biggest effect on your weld quality
    • The tip must never touch the weld or the filler rod, in fact it should never touch anything if you can help it! Even the slightest contact will require you to re-grind the electrode. With Steel this isn't too bad as you'll only loose the small section that touched, with other metals you may wind up having to grind away as much as 10mm of the electrode to restore proper operation.
  • How the pool forms under the electrode, angle of the arc and how it directs the pool
  • Taking the pool "for a walk"
  • Moving patterns, circles, arc, steady, stepped
  • TIG welding is nearly silent when done correctly, the proper sound is a very faint hiss or buzz when using DC, and a slightly louder humm or whine when using AC or pulse mode, there should be none of the popping or crackling sound associated with other welding techniques. There should be practically no sparks or spatter, if you're seeing any of them at all, you've not cleaned the work well enough.
  • What I'm going to do now is to demonstrate how the TIG welder forms and moves a weld puddle, I won't be adding in any filler rod at all to keep things simple. This is usually called "reflow" welding and is the easiest TIG technique.
  • [Demonstrate walking a puddle along a bit of thick material]
Cover the basic technique of establishing and moving a weld bead
Problems

These are some of the problems you might find when welding [Deliberately set up and demonstrate each of these faults]

Problem Symptom Root cause
Bad gas coverage Weld shows porosity or brown discolouration, maybe spatter if extremely bad Gas flow too low won't shield the weld well enough, gas flow much too high will entrain air.
Insufficient power Puddle takes a very long time to form if at all, penetration very poor Current too low is inputting insufficient heat into the base metal to form a proper weld pool
Excessive power Puddle is over-sized, heat affected zone very large, electrode starts to ball up at the tip, penetration excessive Too much current is resulting in excessive heat input into the work and over-heating the electrode causing the tip to melt.
Arc too long Puddle is slow forming, arc sounds/looks like a flame, heat zone very large Having the arc too far away is causing the voltage to go too high and meaning the heat is spread over too wide an area
Arc too short Puddle is tiny, pool rises up to touch electrode Having the arc too short focuses the heat onto too small an area which will make it hard to join workpeices, the short arc causes the pool to actually dome upwards and move towards the electrode. When the tip touches if it gets stick don't try to break it free, stop, let it cool, take the tungsten out of the torch then snap it off the work
Angle too steep Large flame-like arc, elongated puddle, difficulty controlling filler rod The steep angle causes the arc to spread out sideways and fail to remain directly under the point of the electrode, the heat spreads too far down-weld of the torch changing the puddle shape and the plasma jet tends to melt filler rods before they can get to the pool.
Weld contaminated Weld surface is grainy/porous, pool moves erratically Contaminants that were not removed from the weld area prior to welding have got into the weld and disrupted the chemistry of the pool which messes up fusion into the base material.
Travel too slow Heat affected zone very large, penetration excessive Slow movement allows excessive heat build-up within the material which causes the weld puddle to sink into the material and "overcooks" the metal giving a poor surface finish
Travel too fast Gaps/thin spots in bead Fast movement has pulled the bead forward faster than the welder could melt the material
Recognizing faults and knowing how to fix them
Practicing a steady bead Inductee practices moving the puddle on flat stock till competent (may take a lot of time and re-grinding) Getting the basics right
Laying a bead using filler
  • Next step is laying down a bead but adding filler
  • Selecting a suitable filler rod.
    • Material must be compatible with the base material(s) - Note that this does not mean it always needs to be the same as the base material, just compatible
    • Rod size is usually the closest size available to the electrode diameter
      • Too small will result in stupidly high feed in rates and hard to control
      • Too large may tend to "freeze" the puddle when introduced
  • Taking care of who might get hit with the filler rod, turning over the end
  • Holding the filler rod properly
  • Technique for feeding the filler rod through your hand
  • Holding the tip of the filler rod near the puddle so that it's shielded, but not so close it melts
  • Dipping the tip of the filler rod into the nose of the puddle and quickly back out again
    • Contact with the puddle melts the filler rod, not the arc
  • The puddle will rise every time you dip the rod so be careful it doesn't touch the electrode
  • May be helpful to use stepped movements on the electrode

[Demonstrate laying a bead along a bit of thick material] [Demonstrate too little and too much filler] [Inductee practices laying a filler bead]

Laying a bead while using filler

Depending on how things are going and the amount of time available the induction can stop here and allow the inductees to practice welding until they're comfortable with reflow and filler beads. The induction can resume on another day to complete the training on how to actually join metal together. If so the "Shutting down and cleaning up" section below should also be covered.


Topic Detailed contents Rationale
Butt joints

[Coupons used must be 2mm thick steel, thinner makes this too hard for inductions]

  • Can be done with (conventional) or without (re-flow) filler
  • Proper grinding and prep
    • Bevels right way up and properly spaced
    • No bevels if re-flow welding
    • Proper fit-up between parts
    • Option of using backing blocks (temporary and permanent)
  • Using holding magnets and clamps
  • Do NOT tack work to the table
  • Tacking to limit distortion, you are GOING to get distortion
    • Straight, back-tack and half-split tack welding
  • TIG welding doesn't normally use multi-pass approaches

[Demonstration and practice till successful]

Executing the most basic weld
Fillet joints

[Coupons used must be 2mm thick steel, thinner makes this too hard for inductions]

  • Don't need to grind, but parts need to be clean
  • Good fit-up essential
  • Less gas needed for internal fillets, more than usual gas needed for external
  • Proper torch position and angles
    • Biased towards the vertical plate
    • Weaving pattern, spending more time on upper plate
    • Option to "walk the cup"
    • Watching our for under-cutting and how to deal with it.
  • Stitch and alternating stitch to control distortion
  • Pre-compensation for distortion

[Demonstration and practice till successful]

Second most common weld type
Lap joint

[Talk about but don't demonstrate this type]

  • Lack of need for grinding but must still be cleaned
  • Treat it as two fillet joints
    • But watch out for heat buildup in the edges and undercutting
    • Extra care if the sheet is thin to watch for balling up
  • Alternating stitch welds to control distortion
Next joint type
Shutting down and cleaning up
  • TIG welds often don't need grinding back, just a wire brushing may be enough
  • Shutting off and purging the gas before un-hooking the couplings
  • When you're done shut off the power to the welder
  • Put any half-used filler rods back, they can be re-used
  • Leave the tungsten in the torch if it's condition is still good
  • Sweeping up and putting everything back where it belongs
  • Working out your total weld length and paying for it
Clean up after yourself and pay what you owe!
Final thoughts
  • This has only been an extremely brief over-view of TIG welding
  • Do not expect your joints to be structurally sound until you have practiced a lot
  • If you want to weld aluminium or magnesium alloys, TIG-Braze or other techniques then you're welcome to come back for level-2 induction although it's not at all compulsory if you think you can manage these techniques without
  • If you want further tuition then some members of rLab are willing to provide this, but they may charge for it.
Closing comments

TIG welder induction (TIG Mode) Level 2

Level 2 TIG induction is intended to allow people to convert from working on steel to more complex tasks. You must have completed level 1 induction and practiced it to a reasonable level before undertaking level 2. There is a charge of £30 to cover materials, machine charges and trainer time for Level-2 induction, at least a week's notice is required in order to get the necessary materials and the induction is anticipated to take 2-3 hours.

  • Working on and welding aluminium, magnesium, silicon alloys
    • Using AC rather than DC and why
      • Using wave-balance
    • Different electrode types
    • Reduced current handling on AC
    • Connecting the foot peddle
      • Must be used on 2T mode
      • How to set the current range on it
      • Practice using it to ramp up and down current
    • Balling the tip, not necessary but helpful
    • Letting the puddle form then moving
    • The puddle is a lot more fluid than on steel
    • Care with how you use the filler rod
    • Backing down current near edges and as material heats up
    • Anti-cratering at the end
  • Further develop the skills required for more challenging welding applications such as position 3&4 welds
  • TIG brazing
  • Use of 4T mode
  • Using pulse mode
  • Using gas lens system
  • Maintaining & Cleaning the torch
  • When and how to use back-purge (we don't have any fittings for it)