Motorsport Fabrication Fundamentals: TIG Welding
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TIG Welding
10.51
| 00:00 | - It's almost impossible to go to the racetrack or look at any modified car and not see examples of parts produced by TIG welding. |
| 00:07 | Aluminium, titanium, stainless steel and chromoly are common materials in motorsport that will most likely be welded using the TIG welding process. |
| 00:16 | As discussed earlier in the course, TIG stands for tungsten inert gas and is the most controllable and versatile method of welding in the motorsport fabrication industry. |
| 00:26 | Like the MIG welder, a TIG utilises an inert gas as a shielding method but differs in that it requires the operator to manually feed the consumable filler rod into the weld pool, created by the arc from the tungsten electrode. |
| 00:41 | A big reason why the TIG welder is the most versatile welding machine is the adjustability it offers to suit the material we're welding. |
| 00:48 | This can sometimes be seen as a disadvantage though as the complexity of the setup can be confusing for those of us just learning to weld particularly in comparison to MIG welding. |
| 00:58 | TIG welding also requires a lot more technique from us in order to produce strong high quality welds. |
| 01:05 | For the purposes of this module, we'll keep it simple and treat this as a basic start up guide for TIG welding. |
| 01:11 | Let's first take a look at a typical TIG welder and detail some of the features packed into its design. |
| 01:16 | On the back of the machine, we have a 15A plug for the power supply, an on/off switch and a quick release gas fitting for the shielding gas which in the TIG welder's case is typically pure argon. |
| 01:27 | This pure argon allows us to TIG weld aluminium, titanium, chromoly and steel without changing our gas. |
| 01:33 | Attached to the argon bottle is a regulator and gas flow gauge which has a small ball bearing that indicates the rate of gas flow. |
| 01:40 | For most TIG welding situations, we should be aiming to run approximately 6-8 litres per minute that for larger nozzles or cups, we may need a different amount of gas. |
| 01:49 | For now though, this is a great place to start. |
| 01:52 | At the front of our machine we have our TIG torch lead, switch lead, gas outlet and earth lead all connected up and ready to go. |
| 01:59 | It's worth mentioning here that the earth is the positive and the torch is the negative which might seem counter intuitive and something thousands of first timers have no doubt gotten wrong over the years. |
| 02:10 | With the earth clamp securely mounted to our welding table, we can now set up the torch. |
| 02:13 | The tungsten that we're using here is a multi mix which is identified by its pink colour. |
| 02:19 | All tungstens are designated by their colour codes and intended for welding specific materials but the pink multi mix is a great all around option that contains multiple additives of rare earth oxides and offers a stable range of welding amps as well as the capability to weld both AC and DC. |
| 02:36 | The desired length of your torch will dictate what back cap you can fit. |
| 02:41 | We have 3 sizes available to us, short, medium and long. |
| 02:44 | If you're only doing bench welding and not needing to get into tight spaces, you can run the full sized tungsten in the long back cap. |
| 02:51 | For tight places like the inside of cars, you may want to cut your tungsten down and fit a shorter back cap. |
| 02:56 | On the opposite end of the torch we have the gas lens which replaces the more traditional collet body. |
| 03:02 | This uses a stainless grill to diffuse the shielding gas and create a diffused cloud of argon rather than a turbulent narrow stream. |
| 03:09 | Inside the gas lens sits a collet which is used to hold and supply the welding current to the tungsten. |
| 03:15 | Its size is matched to the tungsten size and the wedge on the front of it allows the collet to clamp the tungsten in place when the back cap is tightened up onto it. |
| 03:22 | The most common collet size is 2.4 mm which suits a huge range of amperage levels in both AC and DC welding. |
| 03:31 | For very light applications, a 1.6 mm collet is also available while 3.2 mm options suit the more heavy duty machines and higher amperages which are more commonly associated with industrial use. |
| 03:44 | The gas lens itself is made from heat resistant ceramic or sometimes clear pyrex and is available in many different sizes to suit different applications. |
| 03:53 | Before welding, the tungsten needs to be sharpened but it's common to first cut the tungsten in half as we've already mentioned to allow the use of a smaller back cap. |
| 04:01 | But don't try and snap it as it'll just splinter instead of breaking. |
| 04:05 | Ideally a diamond cut off wheel in an angle grinder will produce a neat cut without contaminating the tungsten, however in reality a normal 1 mm cut off wheel will suffice since the sharpening process will tend to eliminate any contamination anyway. |
| 04:20 | If we've halved our tungsten then we can use a cordless drill and a bench grinder to sharpen it. |
| 04:26 | This can also be done by hand but using a drill tends to be a quicker option that provides more consistency. |
| 04:32 | It's also a great idea to dedicate a grinding wheel to sharpening tungsten as we want to eliminate any cross material contamination. |
| 04:39 | With the wheel running longways across the tungsten, this will develop a grain structure that promotes electrical energy to flow in the direction of the grain. |
| 04:47 | The angle which we sharpen the tungsten at will also affect the width and focus of the arc. |
| 04:52 | As a starting point though, 30° is usually a good compromise. |
| 04:57 | In some instances, we'll also want to remove the very tip of the tungsten after sharpening it to a tight angle as we may accidentally get the tip stuck in the weld pool and we don't want the tungsten tip to snap off and contaminate the weld. |
| 05:09 | Now we can assemble the torch and the length of the tungsten protrusion or stick out should be around 5 mm to start with, although keep in mind that this can vary with different conditions and gas lens sizes. |
| 05:21 | The larger the cup, the longer the tungsten can stick out. |
| 05:24 | It's worth mentioning that TIG welders use a wide range of control methods. |
| 05:28 | Some, like the SWS machine we're using utilise a single screen with a rotary switch to run through the different parameters while others will have separate switches for every single parameter and are more difficult to initially set up as a result. |
| 05:41 | This machine is an AC/DC welder, meaning that it operates with both alternating current which is needed for aluminium and direct current which is needed for mild steel, stainless steel and titanium. |
| 05:53 | For motorsport applications, the AC/DC welder is a must have as it gives us the widest range of welding methods available. |
| 06:00 | The welding amperage will also need to be adjusted to suit the material we're welding and a general rule of thumb and a good starting point is that you'll want 40 amps per millimetre of material thickness. |
| 06:11 | Therefore, welding 3 mm would require 120 amps. |
| 06:16 | In saying that, a 200 amp welder will still be sufficient up to around 5 mm in thickness and cover off most, if not all of our motorsport fabrication requirements. |
| 06:26 | The TIG torch will include a button that can be depressed to begin and finish the weld and this will supply the amps that we've set the machine to. |
| 06:34 | Alternatively we can also use a foot pedal which allows us to adjust our amperage mid weld through the pedal. |
| 06:40 | A fully depressed pedal will give us the peak amount of amps we've set our welder to. |
| 06:44 | Backing off the pedal will decrease the amps and this is great for materials like aluminium which need a lot of heat initially to begin the weld and then require less heat as the weld progresses. |
| 06:55 | Because TIG welding requires us to feed the filler rod into the molten weld pool, we need to select the right filler material for the job. |
| 07:03 | This will usually be the same as the parent metal but there are some exceptions to this. |
| 07:08 | Filler rod comes in packs measured by weight and there are many different types of filler rod available with each different metal having different characteristics that makes some better than others for a particular task. |
| 07:19 | The length of the filler rod is sometimes too long for certain jobs too so particularly when learning, it's a good idea to cut the filler rod in half to improve the control that we have over the feeding motion as it runs through our fingers. |
| 07:32 | This feeding motion takes a lot of practice to get right but once we master it, this can yield beautiful welds. |
| 07:38 | With our welder set up, we can get ourselves ready with the correct PPE to begin welding. |
| 07:42 | The great thing about TIG welding is that it's a very clean process and you're unlikely to get any molten metal or sparks coming off the TIG weld. |
| 07:50 | But it's still essential to wear full coverage clothing to protect against UV rays as well as gloves and a welding mask. |
| 07:58 | Preparation is key with TIG welding as any contaminants on our workpiece will affect the weld quality. |
| 08:04 | Make sure everything you're welding is clean and free of scale or oils and a quick rub with scotch brite and a wipe down with acetone will make the world of difference to your weld. |
| 08:13 | As TIG welding can be a time consuming job, we want to get comfortable and also run through our weld motion in a dry run to make sure that we can smoothly move across the required area of our weld. |
| 08:24 | It's a great idea to hold the torch like a pen and also support the weight of the torch lead by wrapping it around your arm which will improve our control throughout the weld motion. |
| 08:34 | When welding, it's important to keep a minimal arc length, meaning we want the tip of the tungsten to hover just above the weld pool to create a nice central heated zone. |
| 08:43 | If our torch is too high, the arc will spread and create a larger heat affected zone and make the weld pool more difficult to control. |
| 08:50 | The angle that the torch is on is also very important. |
| 08:54 | We want to keep the arc even to both surfaces that we're welding, so that it's not favouring one over the other and move in a direction so that the torch is pointing forwards and shielding the work area ahead of us with argon. |
| 09:06 | Especially when learning, it's common to accidentally touch the tungsten onto the job and if this contaminates the tungsten enough, it'll need to be removed and resharpened on the bench grinder. |
| 09:17 | With that in mind, when you are starting out, it's a good idea to have a few tungstens pre sharpened and ready to go. |
| 09:22 | The motion of the filler rod inclusion into the rod will be something that gets better with practice and the dabbing movement needs to be fluid and timed to the speed of the weld. |
| 09:31 | This is especially important in AC welding as the weld moves quite fast and the amount of filler rod inclusion as well as the consistent timing of this inclusion into the weld is very visible in the quality of the finished weld bead. |
| 09:44 | In summary, TIG welding is most commonly seen with aluminium, titanium, stainless steel and chromoly in fabrication. |
| 09:52 | It's a more complex process than MIG welding, meaning that it's a slower way to weld and takes longer to master but the tidy results and the control that are possible with this type of machine make it more than worth it. |
| 10:03 | There are a lot of considerations when it comes to TIG welding that just can't be ignored as it's quite an unforgiving process that punishes laziness. |
| 10:12 | A good TIG weld starts with proper material preparation and fit up before we even touch the TIG settings. |
| 10:18 | These need to be just right too and dialling In everything from gas flow to amperage to tungsten stick out and much more, is key before you can expect perfect results. |
| 10:28 | While this has only been a short introduction, TIG welding is a skill that's essential for any budding motorsport fabricator and is something that'll greatly increase the range of fabrication tasks that you're able to complete. |
| 10:40 | If you want to master this welding technique, make sure that you check out out Practical TIG Welding course after you've completed this course. |
