preheating with mig 110

admin

Do I need to know how to pre heat with my mig 110?  or is that a method that won't help me with this unit?  If it does have an application for mig 110 units- how do you do it?  I'm imagining my wife wondering what the chunks of metal in the oven are forHobart 125Words mean things
Reply:Far as I know, preheating is most important when you're worried about a weld cracking under stress caused by a difference in cooling rates between the parent metal and the filler metal.  I think it mostly occurs when welding high carbon steels, or restrained welds.  Also large multi pass welds on big plate etc.I would think that for most applications you will be using your welder on, preheat won't be necessary.  I imagine you'll mostly be doing single pass stuff on mild steel.I've found that preheat can help alleviate some distortion sometimes.  But you don't need much more than a propane torch to reach the required temp. on thin metal."Any day above ground is a good day"http://www.farmersamm.com/
Reply:Farmersamm nailed it. Perfectly. For preheating I use a mapp torch/ propane torch, and spread some heat across the thicker section I am to weld, and then I will concentrate a bit of heat on the actual joint where I will weld. I am shooting for the spit test, you want it to scream off the material; if your spit sits there and bubbles, not quite enough preheat. I don't bother to preheat 3/16" material, but I do preheat 1/4" pieces when using a 110v welder. With my miller 175, I preheat 5/16 material. Also, it is important to bevel where you can to get solid penetration, and good filler deposit. A good weld, stuck on the surface can not do the job as well as a weld that can get down into the core of the base material.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.