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Tools/mig/induction: Difference between revisions
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* Machine strikes an arc between the work and a consumable wire electrode, melting a pool of metal
** Welding isn't like soldering, welding melts the pieces of metal and allows them to flow together and mix with the filler material. When it re-solidifies it's one continuous piece of metal
* Wire dips in and out, adding metal to the pool
* Gas shields the hot metal from the air
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* Arc-eye hazard to you and people around you
** Using an auto-darkening welding mask
** Checking masks with a strong light source
** Suitable settings on mask (9-11, 12 maybe - start at 10 and adjust)
** Shouting "Eyes" if there are other people around
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** The voltage is low, but you still don't want to touch it
** Mind what you point the torch at
** Power on this welder cuts off as soon as the trigger is released, which is not the case for all welders.
** NO RINGS, NO WATCHES!!
** Users with implanted medical devices should seek doctor's approval before welding, it's not usually a problem, but please do check
** The welder plugs into
*** Use only suitably rated industrial extension leads, they're in the desk drawer B1B▼
*** Extension leads are a trip hazard, warn people▼
▲** Use only suitably rated industrial extension leads, they're in the desk drawer B1B
▲** Extension leads are a trip hazard, warn people
** If something does go wrong, shut off power before anything else
|| Using the equipment without harming self or others
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* Clean up weld area - be aware of burning paint
* Clean area for earth clamp
*
** No bevel on thin materials
** Regular 2/3rds bevel most of the time
**
** Multipass and double sided welding are options
|| Proper preparation is necessary for good welds, cover bevel patterns for other weld types later
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** Resting your other hand on something to use as a guide
* How the pool forms (Only cover dip transfer)
* The pool wants to move, you need to just keep pace with it
* Keeping the wire aimed at the nose of the pool
** Further towards the tip of the pool = fast move, thinner bead, less penetration
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* Arc won't strike - Ground clamp not connected
* Weld moves around erratically - too much gas or influence from holding magnets
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| Butt joints ||
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** Flap discs will tidy up welds that are good to start with
** Grinding discs will remove messy welds quickly
* Shutting off the gas
*
* Sweeping up and putting everything back where it belongs
* Working out your total weld length and paying for it
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| Final thoughts ||
* This has only been an extremely brief over-view of MIG welding
* Do not expect your joints to be structurally sound or pretty until you have
* The sMIG feature is providing you a LOT of help on this welder, if you switch to a welder without sMIG you may find things a lot harder
* If you want to weld aluminium or magnesium alloys, Stainless Steel, Brazing or other techniques then you can look at [[Tools/TIG/induction#level2|TIG level 2]] or [[tools/mig/induction#level2|MIG level-2]] inductions although it's not compulsory to do level-2 inductions if you've already done the relevant level-1 inductions and if you think you can manage these techniques without further help
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|| Closing comments
|}
<div id="level2"></div>
== MIG Welder induction - Level 2 ==
Level 2 induction should cover more advanced uses
=== Main level 2 induction ===
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*** blowing holes in material - MUCH too much voltage
*** Lots of sparks and brown/porous weld - not enough gas or too far away
* Using tip-dip▼
** The dip is to keep the tip clean, it tends to prevent spatter from sticking to the nozzle▼
** The dip is waxy and has to be applied while the tip is hot so you do a bit of welding first, then dunk the tip into the dip and shake off excess▼
** Only a thin coating is needed and you don't have to reapply too often, every 10-20 minutes of arc time is fine▼
** Spatter can just be rubbed off with a gloves finger as the spatter will not stick▼
* Using anti-spatter spray▼
** The spray is to protect your work if it needs to be very clean and you can't easily clean it other ways▼
** The spray is applied to the work before you start and prevents the spatter from sticking to it. ▼
** You can weld through the sprayed on coating so long as you don't apply it too heavily▼
** But if your welds are structural or otherwise sensitive to contamination, don't use it▼
* Controlling weld distortion
** Metal pulls towards the heat source when it cools and so it pulls towards the weld and in the direction of travel
** You CANNOT prevent distortion, but you can control it.
** Extensive tacking and clamping will help reduce it a bit.
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*** Consider the directions of travel, that can provide a degree of compensation.
*** Subsequent welds on the same joint have diminishing effects on distortion because the other welds restrain it
*** Standard sequence for T-joint (alternating directions on opposite sides) and mitered corners. (
* Working with thin (1mm) and thick (5mm) materials
** For thinner materials heat control is vital, it's easy to heat the work up enough to cause massive distortion
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*** Spray transfer is recommended, although globular transfer might help
* Lap joints of dissimilar thickness and dealing with burn-back issues
▲* Using tip-dip
▲** The dip is to keep the tip clean, it tends to prevent spatter from sticking to the nozzle
▲** The dip is waxy and has to be applied while the tip is hot so you do a bit of welding first, then dunk the tip into the dip and shake off excess
▲** Only a thin coating is needed and you don't have to reapply too often, every 10-20 minutes of arc time is fine
▲** Spatter can just be rubbed off with a gloves finger as the spatter will not stick
▲* Using anti-spatter spray
▲** The spray is to protect your work if it needs to be very clean and you can't easily clean it other ways
▲** The spray is applied to the work before you start and prevents the spatter from sticking to it.
▲** You can weld through the sprayed on coating so long as you don't apply it too heavily
▲** But if your welds are structural or otherwise sensitive to contamination, don't use it
* Welding hardening steels
** Attempting to weld hardened or heat-hardenable steels by conventional approaches will usually result in cracking
** Consider what wire material you want to use, given the strength of joint you need.
*** Aluminium is the very softest wire, but can only be used on aluminium or titanium
*** Bronze is the still quite soft and the most compliant wire usable on steel, it's very unlikely to result in cracking
*** Stainless steel is harder and stronger but does carry more risk of cracks and needs more care
*** Using a hardenable wire gives the strongest result but has the highest risk of cracking
** Differential heating and fast cooling causes the trouble
*** If the steel is hardenable then it WILL harden along the edges of the weld
*** Hardening steels normally contract and pull away from the weld resulting in high tensile and sheer stresses
*** Hardened steels are brittle and easily cracked by tensile stress
*** Most of the trouble occurs because the heat-affected zone around the weld is small and cools very rapidly while the bulk of the material remains unaffected.
** Heat control and management will be needed to prevent cracking
*** Parts can (and usually should) be pre-heated because having the bulk material hot will mean the weld bead cools more slowly
*** Pre-heat temperature is a difficult balance, you'll need to research the metal you're welding and work out if there are any temperature bands that shouldn't be used. If you can't get detailed guidance then temperatures in the range of 250C-400C are normally good. Higher temperatures make the metal harder to handle and increase oxidization but reduce thermal stresses.
*** Work out your clamping arrangements and how you're going to have to move the work around before you start pre-heating, you cannot use clamping magnets because at these temperatures the magnets will be permanently degraded.
*** For small work the [[Tools/oven|materials oven]] may help, for larger workpieces then the blowtorches can be used.
*** Post-heating is used to try to prevent the weld bead from becoming over-hardened
*** This can take the form of simply wrapping the work in insulation to slow it's cooling, or using the blowtorch or oven.
*** Cooling times will vary with weld size, for large welds several hours may be needed
** Post-annealing can help if it's done very soon after welding, before the metal has cooled to room temperature
*** Heating the metal up to annealing point and cooling very slowly can be very effective in relieving stresses in the metal
*** But be aware it may change the bulk properties of the workpeice
** Weld peening can help in difficult situations
* Welding mild steel in position 3
* Changing the gas bottle
* Changing wire, torches and liners, proper setting of wire feed and tension
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Optional modules that can be included in level 2 induction at additional cost to inductee owing to expensive materials needed
* Welding with Aluminium, using suitable gasses. Costs £
* Welding Stainless Steel, using suitable gasses. Costs £
* MIG brazing, which allows joining materials with less heat and distortion, and also works on some materials that can't easily be welded like cast iron and tool steels. Costs £30 extra
* Hard-facing, adding a very hard wear-resistant surface coating to materials using the welder. Costs £30 extra
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