🔥 Gas Brazing Technique

welcome to web comps last time we did some brazing never let's do some brazing today you want to I've got a product over here it's it's a by a local company local vendor it's called LF BFC and it is a low fuming bronze type application here it's got the flux on the outside I like using this stuff for general repair but you know I want to I want to demonstrate just some technique when I tack these up I'm gonna use quite a bit of gap and the reason I want to do that is because I want to show you some heat sensitive if I just poured the heat in here and stuck this rod then I expect this to just fall through the backside we don't want to do that so I want to do this exercise of actually controlling our heat I do want the penetration I want this to show on the backside and I also want to fill this on the front it'll be kind of like a that's an outside corner joint but it's gonna have gap in it so I want to fill this up enough that it's nice and round up on top or at least fused along the edges here so let me get some gear on and we'll we'll put some space in this when I tack these I'll probably light the torch and put a big old dot out here and bring it out a little bit and then I'll I'll get a magnet and I'll have this held up here where it's got some gap and I'll fuse these parts together but I do want to show probably about an eighth of an inch of gap I know that sounds big for 3/16 plate but again I'm trying to show a couple of exercise here of control and how this stuff flows and everything and how to manipulate the torch so old-school stuff I like doing brazing you know I do a lot of repairs on various equipment and you know one of the first things that I consider is brazing I always do for some reason probably because I I just like it so much so let me get my stuff on I'll be right back welcome back I have these tacked at three sixteenths plate I went ahead and put 36 332nd gap maybe a little open there I don't think that's an eighth of an inch I'm gonna call that three 32nd yeah it's pretty good-sized gap if you can see that on camera so the attempt here is I've already had some glass showing here in the galette this glass is like an in pot a product of the flux could we use a bare wire and and powder flux sure maybe we can demonstrate that in another video this one I want to use this product here which is the low fuming bronze product has the flux already on the wire it's just real convenient so I'm gonna start out I'm gonna start heating this up so what's the ding and there's welding so what's going on here how do we make a bond with brazing brazing is generally 840 degrees and above but not melting the parent metal okay so the filler wire is gonna melt at around 840 and it's gonna bond by what we call a capillary action I have cleaned these plates they're rusty down here but they're clean down to pure white metal the flux will pre clean the surface and by this capillary action it will make a bond into the parent metal it's like it it wets in to the parent metal and it sticks and bonds to it soldering is 840 degrees and below so we start talking about these concepts of brazing and soldering what can you do with them and the alloys it gets kind of interesting when you actually look see what's in them and how they melt and how they bond what you can actually do with them and then again how strong they are that's what's that's what's amazing to me is how strong this stuff actually is so let me let me light a torch here and I'll be right back I may put my dark shield on because some of you ding me pretty hard on not wearing a dark shield when I did the brass tree showing how to manipulate this stuff so I may wear my dark shield here you I'm using an acht tip and my pressures my oxygen pressure is set about four pounds my settling pressure is set about buttery pound three psi my torch angle is about 20 30 degrees point are 20 20 degrees pointed forward and you'll notice that I'm taking it out of the pool here I'm this is liquid solid liquid solid so and the reason I'm doing that is because again as I said when we did the intro if I just left this in there and it would probably fall through to the backside and kind of make a mess it'd be too much on the backside I'm trying to get this to round up slightly so I want to fill it in but I don't want it to drip through I want it to show on the backside you know just like just like amperage and voltage when you're wire feed welding you can turn things up how about stick welding could I use a bigger size wire and a bigger tip and more pressure sure I would have probably have to use these do these manipulations a little quicker but and this is a little slow but again I'm trying to show this technique I remember when I first started welding very first thing we did was oxy acetylene welding learn how to manipulate the pool and the filler wire I have laid the filler wire a little lower now every time I introduce the torch it may look like I'm melting the wire with the flame and I'm not I'm creating a weld pool first I'm leaving it right on the leading edge I teach this class in my program I teach oxy acetylene welding brazing silver soldering right alongside the introduction to TIG welding if you think about it it's the exact same hand eye coordination filler wire heat source I think I want to leave this open at the end just to show you what the original gap was I'm gonna do a little remount here I saw a couple of bug holes right on the surface that I didn't like so I went ahead and just remelted him slightly you know could i remelt this whole thing and reshape it sure but then I take a chance of all of it dripping through again I'm gonna go punch this off and I'll probably leave it before I buff it off with a wire wheel or whatever we do to clean it up so let me go quench this off because it's saturated with heat be right back welcome back I finished this part I went over and clinched it and I very lightly touched it with the wire wheel just to get this excess of flux and glass off and I did the same on the back you know we could have gone a little bit hotter we're showing that we melted some on the backside we didn't get through as much as I would have liked for a demonstration but I'm pretty sure you can see this we've gone just a little bit more in heat and let it fall through a little bit it would have bonded on the backside what came through on the back was this it's like a glass it really looks like a glass and so I mean when it solidifies you can knock it off you can chip it off I hit it with a wire wheel again you know it could have gone a little hotter maybe a little more aggressive I just wanted to show this technique of filling this thing up you can see some dark discoloration spots in here I didn't hit this with the wire wheel because this is soft enough that it will rearrange the patterns in here I've left these ripple patterns down here at the bottom of this part I went ahead and hit it with a flapper wheel with a 40 grit I believe it was just to blend this and send this over I mean this thing looks pretty nice very slight bug holes in it which is kind of normal you can go back and melt those out you could send this and polish this off and it just look it looks like gold it's cool so we've done some projects where we're putting some stuff together and we get that color differential you can play around with this and weld some some other types of material other than carbon steel I have my students memorize chemical symbols all kinds of other technical data they think they come in here and they just get strike an arc and that's not so we need to know some things and we need to know about 35 elements of the periodic table for chemical symbols and right here they are technical data we've got a melt point of about 16 24 and height 882 Celsius again I said brazing is 840 and above but not to the melting point of carbon steel that we were welding on so this says that the nominal mu that let me back up the it says to pre clean the joint bevel heavy sections preheat broadly then concentrate oxy fuel neutral flame into the joint area melt some flux off the end of the rod so it'll be activated and it gets down in around the parent metal and then you can start dipping the alloy in melting alloy like we demonstrated here the technical data the nominal analysis says see you 58% so let's see you it's a chemical symbol for copper and SN is 10 1% MN is manganese point 0 4 o % Fe is ferrous iron 0.75% si is silicon point 1 percent with a Zn balance Zn is zinc so now you know what chemically you're working with here and that is typical of all filler metals I don't care if you're looking up a stainless electrode you're going to be giving the chrome the moly the nickel the carbon content anything it's all going to come to you in chemical symbols I have not read I can't I can't remember looking up a technical spec of something that hasn't whether it's a base metal or a filler why I can't remember looking it up and having it spell out chromium or carbon or nickel or molybdenum or whatever it's always the every one that I've ever read is a bit given to me in a chemical symbol fashion so anyway I hope this was fun we'll do some more brazing demonstrations and we might do hopefully we can dream up a project where we can braise it together I know in the past that we did a brass tree and it was an exercise of manipulating this wire and and building this tree and starting out and going all over the place which is a really good exercise for learning how to manipulate the torch and the heat so I hope this helps thanks for watching her videos Bob Moffat with Welkom make sure you subscribe to the videos new videos come out every Monday thank you

Channel: Weld.com

Views: 551,290

Keywords: welding, weld.com, mig monday, tig time, how to weld, learn how to weld, BRAZING, gas brazing, oa brazing, braze, how to braze, braze vs solder, soldering

Id: OL-2yNndGC0

Length: 14min 32sec (872 seconds)

Published: Mon Apr 24 2017