Tools/mig/induction: Difference between revisions

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Revision as of 10:37, 24 September 2019

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

MIG Welder induction - Level 1

Level 1 induction in intended to cover the basics of how to use the MIG welder. It should cover basic safety information and how to use the welder effectively on mild steel in positions 1G and 2G/F. People undertaking MIG induction need to have overalls or other non-flammable clothing that covers all exposed skin except for head and hands, clothes are likely to get burn spots on them. 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 galvanised 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 induction but normal welder usage charges apply, you should expect it to cost around £5 for the induction and a bit more if you spend some time practising afterwards which is strongly recommended

Topic Detailed contents Rationale
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
  • Gas - Most similar to TIG but for safety reasons we won't be doing this at rLab
  • Forge - V.V.Slow, good for big flat welds, high-skilled
  • Spot - Tiny spot welds for joining plate, low-skilled
Which technique to use for which weld
How it works
  • Machine strikes an arc between the work and a consumable wire electrode, melting a pool of metal
  • Wire dips in and out, adding metal to the pool
  • Gas shields the hot metal from the air
  • Earth clamp provides return path
Basic process details
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)
    • Shouting "Eyes" if there are other people around
  • PPE - Overalls, stout shoes, thick leather 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 as soon as the trigger is released
    • NO RINGS, NO WATCHES!!
    • The welder plugs into a 16A socket, there is a 16A trailing socket on the pillar, it's fed from the bandsaw power point
    • If the bandsaw is used at the same time it may trip the breaker
    • 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
Preparing to weld
  • Check metals are suitable
    • Mild steel only at level 1
    • Beware of galvanised 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
  • Bevelling edges to form a path for the bead on butt joints
    • No bevel on thin materials
    • Regular 2/3rds bevel most of the time
    • Bevelling from both sides for very thick
Proper preparation is necessary for good welds, cover bevel patterns for other weld types later
Machine Description
  • Parts
    • Base unit
      • Power source
      • Wire feed mechanism
      • Shroud
        • Annoying "thread"
        • Cleaning out spatter regularly
      • Tip
        • Screwed in barely more than hand-tight
      • Trigger
    • Gas bottle
      • Types of gas and why
      • Regulator
      • Basic gas bottle safety
    • Earth Clamp
  • Controls
    • Gas Flow
    • Wire Feed
    • More complex controls are available at level-2

Wire type, liner and torch can be changed, but not covered at induction level-1

Covering what all the parts are called and which control does what
How to actually execute a weld
  • Normal welder settings
    • Gas at 8L/min will work for most situations but maybe up to 12L/min when very welding thick materials
    • Navigating the menus and selecting SmartMIG mode
    • Setting wire thickness and plate thickness
  • Proper position of self and torch, direction of motion
    • Suitable angles to work at (10-20 degrees ideally, absolutely less than 45 degrees)
    • Push welding - Normal, safe option
    • Pull welding - bigger bead, better penetration, lots of grind and risk of inclusion
    • Vertical and overhead welds are things that can happen, but not covered at level-1
  • Correct distance (10mm is good, anything from 5mm - 20mm is probably going to work if you give sMIG time to learn)
  • Trimming the exposed wire to a suitable length if it's over-long or balled up
  • Proper posture for welding
    • Getting comfortable
    • Supporting the cable if needed
    • Chairs if they help
    • Being comfortable and able to move without stretching is critical for good welds
    • Resting your other hand on something to use as a guide
  • How the pool forms (Only cover dip transfer)
  • Taking the pool "for a walk"
  • Keeping the wire aimed at the nose of the pool
    • Further towards the tip of the pool = fast move, thinner bead, less penetration
    • Further towards the back of the pool = slower movement, wide bead, deep penetration
    • This is your primary method of regulating the travel speed, change you aim point and the rate the bead moves across the work will change
  • Moving patterns, circles, arc, steady, but not too fast or you'll fool the sMIG feature
  • You may need to adjust the shade of your mask to get a clear view
    • Each shade number upwards cuts the light you see in half
    • The temptation will be to look at the arc, but try to focus on the puddle. The puddle is what you need to control and let the machine take care of the arc.

[Demonstrate a good simple weld bead]

Cover the basic technique of establishing and moving a weld bead
Problems

[Deliberately set up and demonstrate each of these faults]

  • Stabbing and poor penetration - too far away from work
  • Weld sticks to tip - too close
  • Bead sitting on surface - too fast
  • Over-penetration - too slow
  • Blowing holes in material - MUCH too slow
  • Lots of sparks and brown/porous weld - not enough gas or too far away
  • Arc won't strike - Ground clamp not connected
  • Weld moves around erratically - too much gas or influence from holding magnets
Recognizing faults and knowing how to fix them
Practicing a steady bead Inductee practices laying down a straight and steady, well-fused bead on flat stock till competent Getting the basics right
Butt joints
  • Proper grinding and prep
    • Bevels right way up and properly spaced
    • 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-track and half-split tack welding
  • Root-weld and multi-pass welding on thick material

[Demonstration and practice till successful]

Executing the most basic weld
Fillet joints
  • Don't need to grind, but parts need to be clean
  • Good fit-up important, will makes things much easier for you
  • Proper torch position and angles
    • Push angle a little steeper than normal
    • Biased towards the vertical plate
    • Weaving pattern, spending more time on upper plate
  • Stitch and alternating stitch to control distortion
  • Pre-compensation for distortion

[Demonstration and practice till successful]

Second most common weld type
Pool Welds
  • Good for joining things that are meant to be bolted in
  • Cleaning up the surfaces
  • Starting from the centre on a small one to ensure fusion to base plate
  • Starting from edge on large pools and may not need to fill it in completely
  • Care with thick base plates as heat dissipation may cause cold-shuts
  • Demonstrate if there's time
Fixing wheels and fittings onto things
Lap joint
  • Lack of need for grinding but must still be cleaned
  • Treat is as two fillet joints
    • But watch out for heat buildup in the edges
    • Extra care if the sheet is thin to watch for balling up
  • Alternating stitch welds to control distortion
  • Demonstrate only if plenty of time and inductee is keen to try
Next joint type
Shutting down and cleaning up
  • MIG welds sometimes require grinding back with an angle grinder to make them neat
    • Wire brush if you don't care about cosmetics
    • Flap discs will tidy up welds that are good to start with
    • Grinding discs will remove messy welds quickly
  • Shutting off the gas before un-hooking the couplings
  • When you're done shut off the power to the welder and putting the leads away
  • Sweeping up and putting everything back where it belongs
  • Working out your total weld length and paying for it
  • Discuss any projects the inductee is working on to provide pointers
Clean up after yourself and pay what you owe!
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 practiced
  • 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 TIG level 2 or 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
  • If you want further tuition then some members of rLab are willing to provide this, but they may charge for it.
Closing comments

Update session for conversion from Clarke 150A unit to ESAB EMP235ic

rLab has recently acquired on loan an ESAB Rebel EMP235ic MIG welder which is considerably more capable than the old Clarke 150A unit but it's controls and operation are a little different so people who've completed induction on the Clarke unit are required to have an update session to be inducted on the EMP235ic. This update session is anticipated to take around 20 minutes.

Topic Detailed contents
Safety Very much similar to the Clarke unit but be aware this machine can output a higher voltage if mis-set. Also as the EMP235ic can output considerably higher currents, darker shades on masks may be called for. This is a 16A unit and should be connected to a 16A or 32A power supply using industrial type extension leads. If using the bandsaw connection point then be aware of the risk of tripping if the bandsaw is in use at the time.
Controls The controls on the EMP235ic are very different, it is controlled via an LCD screen and a menu system. For the level 1 you should only be using the machine in Smart-MIG (sMIG) mode. In this mode you need only tell the welder what size wire you are using and how thick the material to be welded is. You may optionally also set a weld profile but unless you're sure of your needs, leave it on neutral. Gas flow should remain at 8L/min for normal welding operations, optionally increasing to 12L/min for plate above 5mm thick.
Welding Position, travel direction, and spacing should all be the same, but be aware that the welder often starts out a little rough for the first 1-2 seconds as the sMIG feature learns what you're doing an corrects so if the weld sounds odd when you pull the trigger, DO NOT STOP, give sMIG time to correct before you decide there's a problem. Be aware that although this welder is capable of globular and spray transfer welding mode when in manual settings, globular and spray transfer should be impossible to initiate while in sMIG mode. Weave patterns should be executed more slowly than usual to avoid confusing the learning feature.
Welding problems In previous inductions a range of problems were demonstrated for you to learn to recognise. With this new welder in sMIG mode many of those problems are now impossible. You no longer need to consider wire feed rate issues or power issues as those are chosen automatically. Travel speed and torch position still need to be considered as sMIG cannot completely correct those for you although it will give you considerably more margin for error and still get a good weld.


MIG Welder induction - Level 2

Level 2 induction should cover more advanced uses, there will be a charge for level-2 induction to cover the increased cost of materials and trainer time associated with these more complex uses

  • Going into Manual mode on the welder and suitable settings to use
  • Other welding modes - Globular and Spray transfer and the requirements for them
  • Problems
    • Set up and demonstrate each of these
      • Erratic weld, globular transfer - too little wire feed
      • Stabbing and poor penetration - too far away from work or too much wire feed
      • Bead sitting on surface - too fast or too little voltage
      • Weld flat and spattered - too much voltage
      • over-penetration - too slow or too much voltage
      • blowing holes in material - MUCH too much voltage
      • Lots of sparks and brown/porous weld - not enough gas or too far away
  • Working with thin (1mm) and thick (5mm) materials
  • Using tip-dip and anti-spatter spray
  • Welding mild steel in position 3
  • Changing the gas bottle
  • Changing wire, torches and liners, proper setting of wire feed and tension
  • Welding with Aluminium and Stainless Steel, using suitable gasses
  • Option of MIG brazing but no practice unless inductee spends extra for material
  • Option of hard-facing but no practice unless inductee spends extra for material
  • Practicing multi-pass welding