Practical MIG Welding: Tack Welding
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Tack Welding
05.00
| 00:00 | Before we can weld our workpiece together, we're almost certainly going to need to begin by tack welding the pieces to each other. |
| 00:06 | A tack weld is simply a small burst of weld that has the effect of connecting the two pieces together prior to fully welding. |
| 00:13 | The benefit of a tack weld is two fold. |
| 00:15 | Firstly, it allows two or more parts of our workpiece to be accurately located and fit up to be tested and confirmed prior to committing to a full weld. |
| 00:24 | Secondly, if we're not completely happy with how the parts are positioned, it's relatively easy to break the tack weld and try again. |
| 00:31 | Performing a tack weld with a MIG welder is a lot easier than other welding methods due to the automatic feeding of the filler wire. |
| 00:38 | This allows us to use one hand to position the part and the other to pull the trigger and perform the tack weld. |
| 00:44 | Setting up your MIG welder for consistent tack welding will depend on what the welder has in terms of settings. |
| 00:50 | Machines only able to alter wire speed and current won't require any further adjustments to perform a tack weld, simply set the current for the material thickness and the wire speed for the corresponding rate and then control the length of time the trigger is pulled on the MIG gun to produce an appropriately sized tack weld. |
| 01:07 | Depending on the specifics of the material you're welding, a tack weld is likely to require the trigger to be pulled for between half a second and a second. |
| 01:15 | If we have a lot of tack welding to do using a simple machine, it's a good idea to fine tune our wire speed and torch proximity to ensure the wire is burnt back and cleanly cut from the end of the last tack weld. |
| 01:27 | If the machine does have the capability to perform special functions such as spot or tack weld control, then our ability to perform the same size tack weld time after time is greatly enhanced. |
| 01:38 | We did go into this with a little more detail in the earlier machine setup module but to reiterate, it simply refers to a trigger timer that counts down once our trigger is pulled, shutting off the tack weld after the pre programmed amount of time has passed. |
| 01:52 | This can be especially beneficial for operations such as thin sheet metal where we'd be tack welding constantly or large structures that require multiple tacks to hold their position and reduce the chances of thermal expansion and warping as a result. |
| 02:05 | A tack weld or spot weld mode will usually have some burn back control programmed into it. |
| 02:10 | This enhances the start and finish of our welds by controlling the burn back rate of the weld wire at the end of the cycle. |
| 02:17 | This is a new feature that's found on some later model inverter machines and makes restarting the weld a much more efficient process due to the improved condition of the wire that's protruding from our contact tip after use which is used to begin the next weld. |
| 02:30 | As our skills progress, the tack welding process will get faster and faster. |
| 02:35 | You may even be tempted to tack weld things without using a mask and instead just closing your eyes during the tacking process. |
| 02:42 | Unsurprisingly, the safety squint technique is not one that we can recommend unless you're OK with painful burnt eyelids. |
| 02:49 | Breaking a tack weld apart can be as simple as twisting or pulling the material against the tack welds, though it may be necessary to use a grinder to cut a part that has multiple tacks, either way it's still much less work than having to cut a complete weld out and start again. |
| 03:04 | Larger items will require multiple tack welds and may benefit from a small tack on all corners or faces to make sure that it maintains its shape. |
| 03:13 | If we keep the welding process in mind when tacking, we may be able to maintain a uniform weld bead by starting and stopping after and before our tack welds rather than welding over them which will be visible in the finished weld. |
| 03:26 | The fundamental MIG welding techniques don't differ much from those we discussed in the earlier techniques module. |
| 03:31 | It's still vital that we maintain our 10mm of wire stick out and angle our MIG gun so that it's favouring both sides of the workpiece. |
| 03:40 | If we're tacking dissimilar material thicknesses together, then it may be necessary to concentrate the heat into the thicker part by slightly adjusting our MIG gun angle. |
| 03:50 | Motorsport fabrication is quite often a relatively fluid process where changes to the design are made on the fly and tack welding is a process that allows us to position our parts and gain a better understanding of what we need to add or subtract from our assembly. |
| 04:05 | Having the ability to temporarily tack weld our parts together helps us visualise how the project is developing and easily make changes if required. |
| 04:14 | Let's run back through the main takeaways in this module. |
| 04:17 | Tack welding is a crucial step in joining metal pieces together temporarily before final welding them. |
| 04:23 | It aids in workpiece positioning and if plans change, tacks can be easily removed. |
| 04:28 | With a MIG welder, tack welding is relatively easy due to the automatic wire feed. |
| 04:32 | Setting up a MIG welder for consistent tack welding depends on the machine's settings. |
| 04:37 | Simple machines with wire speed and current adjustments only can produce tack welds by controlling the trigger duration. |
| 04:43 | More advanced machines may have a spot or tack weld control for more precise tack welds. |
| 04:49 | Fundamental MIG welding techniques still apply to tack welding such as maintaining a 10mm wire stick out and the proper torch angle. |
