Practical MIG Welding: Preparing Your Work Piece
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Preparing Your Work Piece
04.19
| 00:00 | In this upcoming set of modules we're going to look at all the practical skills needed in the MIG welding process. |
| 00:06 | Before we fire up the welder though, we need to start at the very beginning and take a look at what's involved in preparing our workpiece. |
| 00:12 | Preparation of your workpiece material is the single biggest influencing factor on how well it's going to weld and consequently the quality and strength of the finished weld. |
| 00:23 | Different components need different preparations but one thing that all metals have in common is that they need to be clean and free of dirt, oxidation, rust, oils, mill scale or coatings like paint, zinc, galvanising or chrome to produce consistent and clean welds. |
| 00:40 | As the raw materials go through their initial manufacturing process, they may be oiled, painted or wrapped to protect against the elements in transport and the storage phase. |
| 00:50 | If you're planning on storing your materials for any decent amount of time, it's a good idea to leave these protections on the material to prevent any oxidation from forming. |
| 00:58 | Regardless of the metal type, it's important to give it a proper wipe down before cutting to length. |
| 01:04 | This eliminates any oils being introduced into the metal from the cutting process and improves the overall cleanliness of your material preparation. |
| 01:12 | Acetone is used in fabrication because of its ability to remove all traces of oils, then evaporate from the material without leaving any residue. |
| 01:20 | Using degreaser, brake clean and other cleaning agents isn't the best idea because they tend to leave residues that will affect the weldability of your workpiece or contaminate your weld. |
| 01:31 | Just remember that acetone is highly flammable so store it and the rag that you're using to apply it well away from your work area when you've finished with it. |
| 01:40 | The way we cut and remove material is also going to affect the welding process. |
| 01:45 | High speed chop saws and angle grinders that use an abrasive cutting disc will deposit small amounts of the material into the cut area, contaminating the joint. |
| 01:54 | Cold saws or band saws that use a slower cutting speed with a metal blade can also contaminate the cut area because they tend to use coolant to assist in longer blade life. |
| 02:03 | This coolant can also introduce oil into the cut area and contaminate our weld. |
| 02:09 | Although it's impossible to completely eliminate this contamination, we can effectively reduce it by using a saw with a cutting wax that will prolong the blade's life but also minimise oil inclusion into the cut area. |
| 02:22 | After each cut we need to deburr our material with a file or a deburring tool and give it a wipe with acetone. |
| 02:28 | When working with tube, it's important to consider cleaning the inside of the tube as well as the outside. |
| 02:34 | By doing so you'll drastically reduce the amount of smoke that's emitted when it comes time to weld, also improving the quality of the finished product. |
| 02:42 | If you're building a roll cage inside the confined cabin of a car for example, this can dramatically reduce the respiratory health risks associated with welding. |
| 02:51 | All materials need to fit together with minimum gaps to achieve consistent, high quality welds. |
| 02:57 | While MIG welding does give us the ability to bridge some quite significant gaps, doing that will also input more heat into the weld area and make for an ugly finished weld. |
| 03:07 | The better the fit up, the better the finished weld so it's worth taking extra time and care during this part of the fabrication process. |
| 03:16 | Once we have our parts fitting correctly, internally cleaned and deburred, we can concentrate on the outside of the weld area. |
| 03:23 | For steels that are painted or coated, we need to remove the coating in the area required for welding. |
| 03:28 | It's best to remove this at least 25-50mm away from the weld joint. |
| 03:34 | There are a few ways that this can be done. |
| 03:36 | For painted or plated steels, we need to buff the weld area clean with a belt sander, linisher or a flap disc on an angle grinder. |
| 03:43 | Clean steels like unpainted mild steel tubes need to be buffed with a handheld scotch bright pad to remove the outer layer and create a nice luster to the steel. |
| 03:52 | So, to wrap this module up, spending the time and effort on the preparation stage makes a big difference when it comes time to weld. |
| 03:59 | Having a well prepared and cleaned workpiece means you're likely going to find the setup, settings and welding processes detailed in the next module significantly easier to do so taking the time to do this step right will ultimately save time and improve your results and confidence with MIG welding. |
