Practical TIG Welding: Part Preparation
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Part Preparation
07.25
| 00:00 | - At this point in the course we've covered many aspects of TIG welding from a technical standpoint, however to become proficient at welding, you're also going to need to understand and master a range of practical skills which we're going to cover in this set of modules. |
| 00:14 | Through these modules, you'll learn the correct technique and approach to each skill and from there, it's going to be up to you to put in the time to master them. |
| 00:23 | Since correct preparation of your workpiece has the biggest influence on the quality and appearance of your completed weld, we'll start here. |
| 00:32 | Different components need different levels of preparation but one thing that all metals have in common is that they need to be clean and free of dirt, oxidation, rust, oils, milscale or coatings like paint, zinc, galvanising or chrome in order to produce consistent and clean strong TIG welds. |
| 00:53 | We can't stress enough how important this preparation is and the more time we spend here, the easier the actual welding process will be and we'll also end up with a better quality and stronger finished weld. |
| 01:06 | With this in mind, we'll usually find ourselves spending more time on the parts preparation than the actual welding. |
| 01:13 | This could almost be considered the secret of every professional fabricator. |
| 01:18 | Taking the time at the start of the job to ensure that the parts preparation is done thoroughly and that we're left with clean material that's free of impurities or contamination and fits perfectly. |
| 01:30 | This can be an easy thing to overlook, especially when you're eager to get straight into laying down some beads but we can assure you that the time spent here will pay dividends. |
| 01:41 | Let's start with the material you're going to weld. |
| 01:43 | If you're dealing with raw material then it's likely that it will be oiled or wrapped to protect it against the elements in the transport and storage phase. |
| 01:52 | It's a good idea to leave this protection on the materials if you plan on storing them for longer periods of time to limit any rust or oxidation forming as well as to reduce their exposure to contaminants from your fabrication space. |
| 02:06 | If you're dealing with existing materials, perhaps part of your vehicle structure, or another component that you're welding to, then this material may be painted, plated or perhaps anodised. |
| 02:16 | We may also have surface rust to contend with on ferrous materials. |
| 02:21 | As part of the preparation step, you're going to need to remove anything that's on your workpiece to reveal the clean base metal beneath. |
| 02:29 | We recommend removing any coating around the weld area at least 25 up to 50 mm either side of the join. |
| 02:36 | This can be done a few different ways. |
| 02:39 | For painted or plated steels, you'll need to buff the weld area clean with a belt sander, linisher or a flap disc on a grinder. |
| 02:46 | Clean steels like unpainted mild steel or chromoly tubes can be buffed with a hand held scotch brite pad to remove the outer layer and provide access to the clean base material below. |
| 02:57 | Even when we're dealing with uncoated raw materials it's also important to give it all a wipe down with acetone before handling and cutting it to length. |
| 03:06 | This is going to prevent any protective oils being introduced into the material while we're cutting it and this will improve the overall cleanliness of your material. |
| 03:15 | Acetone is used in fabrication because of its ability to remove all traces of oil and then evaporate from the material without leaving any residue on its surface. |
| 03:26 | Using degreaser, brake cleaner and other cleaning agents isn't advisable because they may leave residues that could adversely affect the weldability of the workpiece or even contaminate your weld. |
| 03:38 | Just remember that acetone is highly flammable so put it and the rag that you're using well away from your welding bench when you've finished wiping down the part. |
| 03:47 | If we're working with tubing, it's important that we also pay close attention to the internal surfaces of the tube, not just the outside. |
| 03:55 | If there's oils or contaminants inside then this can impact on the finished weld quality, not to mention emitting smoke as the material heats up during the welding process. |
| 04:06 | This can be a real problem when you're working in confined areas like the interior of a race car. |
| 04:12 | Deburring the inside of the pipe followed by a quick wipe with a rag and some acetone will eliminate these contaminants easily and reduce those risks. |
| 04:21 | Irrespective of the material you're working with, proper fit up is one of the most critical parts of a quality TIG weld. |
| 04:29 | As we've already learned through the course, this is even more critical if you're working with chromoly as it's very sensitive to heat and can become brittle in the heat affected zone if excessive heat is applied during welding. |
| 04:41 | Unlike MIG welding, which gives us the ability to bridge even quite large gaps between the material we're welding together, this is not the case with TIG welding. |
| 04:50 | A tight fit up with a minimal gap means that we don't require as much heat and this will also allow a more consistent weld which is not only going to look better but is also going to offer more strength. |
| 05:02 | This is probably the most common place we see novices try and take shortcuts and it can be tempting to have a close enough is good enough attitude. |
| 05:12 | Particularly with some of the more fiddly and complex junctions between multiple parts. |
| 05:17 | Again, this is not the place to try and save time and your patience here will be rewarded when you finally pick up the TIG torch. |
| 05:25 | If you want more tips on achieving a perfect fit up then our fabrication fundamentals course is an excellent resource. |
| 05:33 | The way we cut and prepare our material for TIG welding can also have a significant impact on the quality of our welds. |
| 05:39 | Introducing oils and contaminants into the material when we're cutting it to length can make welding much more difficult than it needs to be. |
| 05:46 | Tools like angle grinders or drop saws that use high speed abrasive cut off wheels can embed particles in our material as they're cut. |
| 05:55 | If these aren't cleaned up using a hand file, they can then contaminate the weld area leading to ugly and weak welds, not to mention causing a lot of frustration as you try to lay down a quality weld. |
| 06:07 | This is why the preferrable method of cutting the raw material is either with a band saw or a slow speed metal cold saw. |
| 06:15 | Technically a cutting fluid or lubricant is recommended with either of these cutting methods and it will extend the life of your blade, however care is still required if you want to go down this route. |
| 06:26 | Using cutting fluids that contain oils and chemicals will also introduce contaminants into the material which is why using a cutting wax is preferrable. |
| 06:35 | Even this still requires cleaning with acetone before welding to remove any residual wax. |
| 06:40 | We would recommend using a cutting wax if you're using a hole saw to notch roll cage tubing as otherwise the hole saw life with be dramatically reduced. |
| 06:49 | On the other hand, with our own band saw here at HPA, we don't use any lubricant and have been using the same blade for well over a year with no obvious signs of wear so in this respect, a lubricant could be considered a personal preference. |
| 07:04 | By spending the necessary time in this step of the process to achieve proper fit up and a thoroughly clean and contaminant free work piece, you're going to find the remaining steps in this process become infinitely easier and you'll see the fruits of your labour in the quality and ease of your finished weld. |
