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Tools/TIG/induction: Difference between revisions
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{{inductioninfo}}
<div id="level1"></div>
== TIG welder induction (TIG Mode) Level 1 ==
Level 1 induction in intended to cover the basics of how to use the [[Tools/TIG|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
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* 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 ||
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** 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!
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* 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
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* Gas bottle
** Type of gas and why
** Basic safety for the Albee bottles
|| Covering what all the parts are called and do
|-
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** 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
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** 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
** 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
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* 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
** Connecting cylinder▼
▲** Setting suitable gas flow rate using both bottles using the table on the welder, but consider situation of weld
||
Suitable setup and settings for executing the weld
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** 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
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* 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
{| class="wikitable"
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! Basic Current & Gas !!
|-
| Inside corner || +10% current
|-
| Outside Corner || -10% current
|-
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|-▼
|-▼
|}
** 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
** 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
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* 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
* 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▼
** 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
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| 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
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** 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]
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| 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
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| 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.
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| Travel too fast || Gaps/thin spots in bead || Fast movement has pulled the bead forward faster than the welder could melt the material
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| Laying a bead using filler ||
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* 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
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[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.
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! 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
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|-
| 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
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| 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
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|-
| Final thoughts ||
* This has only been
* 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
|}
<div id="level2"></div>
== TIG welder induction (TIG Mode) Level 2 ==
Level 2 TIG induction is intended to allow people to convert from working on steel to
[[Category:inductions]]▼
* 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
*** 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)
▲[[Category:inductions]]
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