We are putting a new undercarriage on a Liebherr PR731CL and the supports for the front idlers are worn pretty bad. Thinking of just cutting off the existing shim or wear plate , veeing out the steel and welding on a 3/8 or whatever we need thick plate of AR400 or AR500. What do people like to do for this repair? My buddy who is a welding engineer is a little nervous about welding the AR, he thinks it will crack. I am sure some people around make repairs like this all the time? Thanks!
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Just find the appropiate size of steel, grind some off so that the weld does not stick out. Use some 7018 style rod like Arc-Tec 223 and I would use probably 3/32 or 1/8 size rod. I would just stitch weld it in place. Put some markings with some engraver or Zip-Disc so as to know exactly where they need to be installed, as you will be grinding up that face to be clean for welding. The markings is the first job not after it is off. If done this way, you will be sucesssful. Simon C
I never quick fixed anything on dozer track frames, maybe 1 or so rollers etc. I would work on it or weld on it like they would in the factory, meaning its not on the machine, so much easier to have them off, and the welds are much stronger and just better when doing them flat and horizontal. And best of all hot stuff will not go down to your arm pits or ? Yeah not all of us had the proper garments back in those days. Polyester in coveralls did not help.
hahaha… well now days we have this thing called MIG welding We thought about taking it off, I guess just weren’t too sure on that. I think we will be able to get this repaired up nicely.
I have a problem of over-fixing stuff by making the repair like it came from the factory. In the meantime, the rest of the machine is falling apart. I'm trying to break that habit but it's hard. Hope you find the right amount of 'fix' for your machine.
Gee.....so my welder friend that people came to from all over to fix the tough jobs that others tried and failed.... Had several MIG welders, yet always did these type repairs as mentioned above by SimonC....with 7018. HaHaHa......
Or depending on where, maybe 8018
It can be worth opening 10# can of 7018 for something like this but fix a whole load of similar with years old can. Depends a lot on how many passes and how much weld, how much restraint. Warm the thick heavy pieces up some before starting and more if using wire. They do make higher shock wire, a bud in the tile biz had to use it but if I can do it am all over wire if I can. The alloy is good and doesnt have some storage issues. Makes building and filling fast and clean.
That would be done in place. Wouldnt be taking a whole machine apart, would be cheaper to hire someone can weld overhead. That is near a dream for a portable guy,,, clean, easy, out in the open, not in the mud.
I think we will try it and I will report back. aiming for a preheat of 5-700F with regular ol wire.
It doesn't need that much heat as 375 degrees wil heat a Komatsu wear sleeve to install on crank and change its colour. Warmed up well will be sufficient from the ones I have been involved in. Simon C
Warmed up till you can still quickly touch it is fine. About 300 deg's. If you only have MIG available run it hot and make sure to do a slight weave to insure fusion on both edges. 8018 would be the best option but 7018 would work if you can get a stick welder. I don't know if you could get strips of medium carbon steel like 1030 or maybe 1045?? It would be a little harder and last longer.
It may be just me but that looks like that had a wear strip on it. It might be as hard of fix as you think.The only thing if the wear strips are as hard as Cats were if i remember right I think they had to weld them on with a special rod
I have fixed a few of these same problems and I can say that with some good 7018 rod or Arc-Tec 223 and some decent wear strips it is quite easy. I use a zip disc grinder to leave marks on the location I want to put them, with marks extended out couple inches past where they go so that when all is grinded clean, I still know wherre to weld the new strips in. Preheat with tiger torch till good and warm and stitch weld on. They never broke off. Simon C
And yeah what size Mig unit? Not the best for outdoors, unless cored, would take some good size wire for some projects too. All I ever used was 7018 stick on the big projects, some mig on dump boxes here and there. Mig is great for sheet steel, and 1/4 inch.
A lot of people mention Mig welding but don't really understand that there are different types of welding that use a wire feeder. Just for Mig that is solid wire there are 3 modes of metal transfer based on the voltage and shielding gas. Then there's flux-core that uses a hollow wire with the flux inside. Flux-core can be self-shielded or also use shielding gas (dual-shield). Then there's metal-core that is kind of a cross between Mig and flux-core with metal powder inside the wire and also uses shielding gas. All of these different processes are often referred to as Mig welding. The right process depends on the type of steel and the desired mechanical properties. Preheat, post heat, slow cooling and other techniques such as peening may also be required. When people just say Mig they need to be more specific as Mig is a pretty generic term unless talking about thinner steel/metal. Submerged arc is another wire feed process that pours powered flux over the puddle that turns to hard slag. The slag can be ground up and reused. Some shops mix used flux with new flux.
So I would guess that any outdoors MIG welding is always flux cored, dual shield would not like a breeze. And what size wire would be used for say welding 1/2 inch plate up to 1 inch plus? And what power supply? I've used 1/4 inch sticks at times on some thick sections.
.045 will do just fine up to 1". Just need multiple passes. Anything bigger is going to need a pretty good machine.
You can use dual-shield outdoors if you put up some screens and it's a calm day with no wind. Self-shielded flux-core is more expensive, especially to get the same mechanical properties as dual-shield. Dual-shield doesn't come in a basic general purpose wire. The base wire has mechanical properties comparable to 7018 stick. Self-shielded basic wire is more like 7014 or even 6013 and not designed for dynamic loading. Dual-shield has better pentration too. .045" is a good basic size and most can be run out of position/vertical up. You can turn it pretty high too, 300 amps plus. 1/16" is common for larger welds on thick plate without being too hot but usually needs a 400 amp machine or bigger. You really need to consider duty cycle of the welder when running flux-core.
Interesting why u did not mention "pulse" system machines, as is a heck of diference in fusion. Nevertheless i rarely use the wire welder in this type of jobs, the 7018 is the 4x4 for this purpose, as we never know what type of stell OEM used when building the part. High carbon content steel may not be the best option for a repair like this, the carbon interacts a lot with heat and easyly gets microcracks. I´ve been best succeded in this repairs using good quality boron stell, like a pieces of a track pads, it welds nice, is relativelly hard and resistent to shock and abrasion. But certainly the Book mentions what type of steell to use and weld system.
I don't know if you really need pulse for heavy equipment repair. It's good for solid wire on thinner material or metals other than steel. It doesn't really give more fusion if the welder uses the proper heat without pulse. It might give faster deposition and less distortion but again that's on thin material. Not much is that thin on heavy equipment welding. No real benefit with Dual-Shield Flux-Core.