Tools/mig/induction
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[edit]
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 £10 for the induction and a bit more if you spend some time practicing afterwards which is strongly recommended
Before the induction the inductor should prepare coupons consisting of 4 sheets of 2mm mild steel sized 200mm x 50mm and one of which has been drilled with 6 x 10mm holes. All edges cleaned and deburred but mill-scale left on the sheet. One additional bit of steel, thickness >1.5mm and size > 150mm x 150mm will be required for stringer bead practice and faults demonstration.
Topic | Detailed contents | Rationale |
---|---|---|
Types of welding available |
|
Which technique to use for which weld |
How it works |
|
Basic process details |
Safety |
|
Using the equipment without harming self or others |
Preparing to weld |
|
Proper preparation is necessary for good welds, cover bevel patterns for other weld types later |
Machine Description |
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 |
[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]
|
Recognising faults and knowing how to fix them |
Practising 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 |
[Demonstration and practice till successful] |
Executing the most basic weld |
Fillet joints |
[Demonstration and practice till successful] |
Second most common weld type |
Pool Welds |
|
Fixing wheels and fittings onto things |
Lap joint |
|
Next joint type |
Shutting down and cleaning up |
|
Clean up after yourself and pay what you owe! |
Final thoughts |
|
Closing comments |
MIG Welder induction - Level 2[edit]
Level 2 induction should cover more advanced uses. Normal machine usage charges apply during this induction, you should expect it to cost around £10-15 plus more for practice afterwards if you want to (Strongly recommended)
Main level 2 induction[edit]
- Going into Manual mode on the welder and suitable settings to use
- How to select manual mode
- Selecting the proper material in use on the menu
- Adjusting wire feed rate and voltage, simpler welders may use an arbitrary scale for voltage, or may not be constant voltage at all and use an inductor to control things. In that case you'll just have to feel you way through finding the right settings. Especially be aware of shitty £100 welders that may have very erratic wire feed rates.
- You don't set current, that's controlled by the interaction of voltage and wire feed rate
- Manual mode is useful for learning, especially if you expect to have to use fully manual welders elsewhere, but sMIG will almost always give better results when available.
- Other welding modes - Globular and Spray transfer and the requirements for them
- Describe conventional (dip) transfer, globular transfer and spray transfer
- Globular transfer is normally undesirable as it's hard to control but it can achieve a deep penetration at the cost of severe splatter and difficult control
- Globular has a weird sound, a quiet hiss that's broken by a sharp crack a couple of times per second
- Spray transfer is a very high powered welding technique used for deeply penetrated welds on thick material
- The EMP235ic can just barely achieve spray transfer when loaded with 0.6mm wire and with a low-CO2 argon blend gas
- Spray transfer is very quiet in use, just a quiet whisper. It also produces a LOT of UV light so you'll need a darker shade than normal
- Both globular and spray transfer modes are only suitable for use on horizontal welds, they cannot be used vertically or overhead
- 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
- Set up and demonstrate each of these
- 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.
- Tack a lot, correcting distortion as you go
- Pre-compensation can help
- Bridge blocks on the back of a weld can restrict it a lot
- Order of welds within a joint can be used to help cancel out distortion.
- 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. (outside, sides from inside to outside, inside in opposite direction)
- 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
- As with all welding good tacking technique can limit this
- Welding only in very short bursts
- Building welds up entirely from tacks (on both sides when possible) is an effective option
- Very high risk of blow-through if you try to seam weld something
- Changing to a thinner wire will help, if your wire is thinner than your material it's easier to control
- sMIG helps enormously here, far easier than manual, but make sure you train it properly first
- For thicker materials the challenge is usually getting enough heat into the material
- For materials up to 5mm or so then single-pass welding is possible but relatively high power levels will be needed
- The difficult part is getting enough heat into the work to allow the bead to penetrate fully, without dropping out the bottom
- Thicker wire will help here by allowing you to add more material to the weld pool at a higher rate
- A wide weave will be needed in order to make sure the puddle melts into both sides correctly without causing under-cut
- Undercuts are normally caused by too long an arc, too much power, or failing to pause at the edges of the weave
- An ideal weld will fill the gap and protrude from the surface by 0-3mm, without any sunken areas or under-cuts
- Multi-pass welding
- For very thick materials (6mm+) is is likely that this welder will struggle to achieve an acceptable single-pass weld, so multiple passes will be needed
- Multi-pass welding can be done from one or both sides depending on access. Distortion control will be very much easier if it can be done from both sides
- Bridge blocks are normally used on multi-pass welds
- The first pass (called the root) focuses on fully closing the gap at the bottom of the weld with complete penetration, and without causing too much distortion
- Welds must be cleaned (normally with wire wheel) in between passes
- Subsequent passes (called fill) are made with a normal welding technique to fill up the grove to just below surface. Alternating sides and directions will help reduce distortion
- Final pass(s) (called the cap) are made with a much wider than normal weave to finish off the surface and to leave it protruding 0-3mm as for other welds.
- Very thick materials (8mm+)
- Standard short-circuit transfer MIG is not recommended on materials >8mm thick
- It will be very hard to get enough heat into the work to achieve full fusion
- Spray transfer is recommended, although globular transfer might help
- For thinner materials heat control is vital, it's easy to heat the work up enough to cause massive distortion
- Lap joints of dissimilar thickness and dealing with burn-back issues
- 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 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
Optional level 2 modules[edit]
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 £15 extra
- Welding Stainless Steel, using suitable gasses. Costs £15 extra
- 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
MMA (Stick welding) Induction[edit]
This induction in intended to cover the basics of how to use the MIG welder in MMA (stick welding) mode, it covers basic safety information and how to use the welder effectively on mild steel in positions 1G and 2G/F. It is strongly recommended that people undertake MIG induction and practice it thoroughly before attempting stick welding, that said you can start welding straight away with stick but it's likely to take considerably longer to develop the required skill to use it effectively. People undertaking stick welding 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 is a charge of £10 for the induction to cover materials and a bit more if you spend some time practicing afterwards which is strongly recommended. The needed materials are usually kept in stock but if we've run out it will take several days to get more. This induction is estimated to take 1-2 hours.
Topic | Detailed contents | Rationale |
---|---|---|
Types of welding available |
|
Which technique to use for which weld |
How it works |
|
Basic process details |
Safety |
|
Using the equipment without harming self or others |
Preparing to weld |
|
Proper preparation is necessary for good welds, cover bevel patterns for other weld types later |
Machine Description |
|
Covering what all the parts are called and setting current |
How to actually execute a weld |
[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]
|
Recognising faults and knowing how to fix them |
Practising 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 |
[Demonstration and practice till successful] |
Executing the most basic weld |
Fillet joints |
[Demonstration and practice till successful] |
Second most common weld type |
Lap joint |
|
Next joint type |
Shutting down and cleaning up |
|
Clean up after yourself and pay what you owe! |
Final thoughts |
|
Closing comments |