Heavy Equipment Repair Question

[milon]

Hello all,

We are a quartzite rock quarry located in the Utah/Nevada desert. It is small family owned operation that sometimes can afford a decent welder and sometimes cannot. When we cannot, my dad and I fill in the best we can do.

For most projects, we do ok and have lasting results. For some heavy equipment repair, we have failed to have good results. Rewelding heavy ripper teeth and trackhoe buckets have sometimes failed. Our application is much harder on equipment than normal excavating/ripping, and any weakness is quickly exposed.

Most of the failures have not been the welds themselves, but rather in the orignial material next to them. Dad says that he thinks this could be due to crystallization of the original material durring the welding process. I have heard that preheating the material before welding can help. Is this recommended? If so, how would we go about heating such large pieces of metal? What temps are required, and how do I know when we get there?

We use stick or a Lincoln LN-25 Wire-Feed with Lincoln 400Amp Desiel Welder for on-site repair, but most projects can be brought down to the shop where we use a Lincoln MIG 225. We have carbon gougers that I have used to clean out cracks on implements and machinary before rewelding them. I am decent at running a bead, but lack real knowledge about heavy equipment welding.

Any help would be apriciatied. I will try to answer any questions that you may have in trying to understand either our problems or process...etc.

Also, is there a welding instructional manual that you would recomend getting that would cover Heavy Equipment repair?

 

[skyking1]

Welcome!
We have a sub forum for welding in the shop forum. You might get better help if your thread title is changed and moved to that location.
@CM1995
Might come along and do that for you.
I can't say what the answer is except sometimes metal gets tired and yes it breaks next to the weld.
I did not preheat the welds much on my bucket repairs, but I'm not mining either.

 

[Junkyard]

Preheating anything heavy like that never hurts. It gets the moisture out and keeps it from cooling so fast it cracks welds. It’s also helpful when possible to wrap whatever you welded in a blanket to help it cool evenly.

My first question is what rod or wire are you using? That will have considerable affects on the strength of the weld and penetration. Beyond gouging out cracks are you starting your welds on clean metal? For the thicker repairs have you beveled things enough that you can put down multiple passes?

There are books on welding but I’ve never seen any specific to heavy equipment.

 

[John Shipp]

I am also interested to know the proper procedure for pre-heat and how to quantify, as my method is a kind of "Use the force, Luke" type of act, basically I preheat for a period that just seems right. Once that point is reached (?!) I get to welding and as long as welds keep going in over the area I figure it's warm enough and try to keep going til a section or piece is done.

Never considered keeping it warm afterwards,, that sounds like a good idea.

 

[cfherrman]

Saying this I know very little about welding.

The heat from the weld changes the temper of the material next to the weld and makes it brittle, and makes it a failure point. Preheating and tossing a blanket over will probably help a lot.

Hire a welder and see what he does then copy it

 

[Nige]

There are books on welding but I’ve never seen any specific to heavy equipment.

Cat have prodcued a couple, obviously predicated towards heavy equipment welding repair.
One is called "Service Welding Guide" - Pub Ref SEBD0512.
The other is "General Welding Procedures" - Pub Ref REHS1841 which believe it or not was last updated just over 6 months ago.

 

[skyking1]

I use the weed burner for a lot of my pre and post heating because it's cheap and easy.
Acetylene is really expensive!

 

[Junkyard]

Cat have prodcued a couple, obviously predicated towards heavy equipment welding repair.
One is called "Service Welding Guide" - Pub Ref SEBD0512.
The other is "General Welding Procedures" - Pub Ref REHS1841 which believe it or not was last updated just over 6 months ago.

I’ll look them up, most of what I know is monkey see monkey do from the years of chasing pier drilling rigs. If something can be f**ked up they can do it. We built a lot of our own tooling as well. Lately it’s been excavator buckets, several getting new shanks and one had the floor tore off of it. Finally bought the equipment to run 1/16” dual shield to cut down on the welding time.

 

[Junkyard]

I use the weed burner for a lot of my pre and post heating because it's cheap and easy.
Acetylene is really expensive!

That’s usually what I use as well. A few hundred degrees is all you need. Too hot and you can’t stand to get near it to work.

 

[Nige]

If you have access to SIS you should be able to find REHS1841 easily.
SEBD0512 is more difficult to find. It comes from the late 1970s (I think) when it was published as a soft-back book. I have a copy but it's back home. It's now classed as a Reuse & Salvage Guide and therefore requires dealer access to SIS to find it.

 

[BC Placer gold]

I use the weed burner for a lot of my pre and post heating because it's cheap and easy.
Acetylene is really expensive!

Same.

Arctec 223 rods are very popular here, similar to 7018 but supposedly higher elasticity/tensile strength. Used successfully for bucket armouring, tooth adapters etc. I do ‘bush’ repairs; not a professional welder by any means….but haven’t had a failure.

But…we are only excavating gravels or highly fractured/weathered bedrock (siltstone/argillite/tuffs etc)

Quartzite would certainly be much harder digging…

 

[Tugger2]

The 400 Lincoln and LN 25 are the right machines for heavy equipment repair. Keep your mig welder away from anything over 1/4" thick. If your working outdoors welding cracks and minor stuff just use 7018 ,keep a selection of sizes from 3/32 up to 1/4" and keep them dry. Arctec 223 is awsome stuff but expensive. Arctec also makes some really good hardsurface rod,ecoface60 and hardcro63 are great for extreme wear on corners and edges.
Get a good pre heat torch.Talk to your welding supplier about a big propane/oxygen rosebud. A tiger torch/weedburner does ok but dosent come close to propane /oxy. If you have an oxy acetylene rosebud throw it down a well somewhere,they heat until your almost ready then they backfire .Things get cold as you try and relight them over and over.Oxy acetylene is great for cutting,i pfefer it over propane for cutting ,just not heating.
when you say carbon arc im assuming your talking about Arc air gouging another essential tool around heavy equipment repair. Just be fussy grinding out after gouging with arc air.
Im not sure if they still publish the Lincoln Procedural Handbook of Welding but its full of good information. Mine is 1974 ,it was like a bible to me when i was a young welder in logging camps.Even if you find an old one it will relate to a lot of your repairs.
Your LN25 can run gasless wire which is ok, but if you get it set up with Co2 and fluxcore wire for shop work its great stuff. as i said earlier keep the hardwire for light repairs .
That would be my basic choice of gear in your application . Some practice and some reading up will fine tune your skills.

 

[skyking1]

Nice post tugger.
When I was doing it, we used to get stoody hard facing rod.

 

[BC Placer gold]

Yes great info, appreciated!

 

[Welder Dave]

Just for preheating a weed burner is plenty. You very rarely need over 400F. High manganese steels have to be kept below 500 deg's. Rosebuds have more concentrated heat if you need to get something hot enough for bending or maybe stress relieving. Even with an LN25 dual-shield wire has better mechanical properties when used on a CV (constant voltage) machine. The filler metal makes a difference but you don't usually need to buy expensive specialty rods. Arctec 223 is basically 8018. Common 8018 is actually 8018C-3. The C-3 means it has 1% nickel for extra toughness. It really helps to know what type of steel you're welding. Some buckets and other attachments could be T1 steel or abrasion resistant steel like AR400 in which case they need specific filler metals. In general 7018 or 8018 will cover most repairs but if you can find out the actual material, then you can get the recommended filler metal for it. It has been mentioned in the past that using a higher tensile filler like 11018 can do more harm than good. There are things you can do to help prevent failure. Preheat, peening after welding while still hot, slow cooling or even post heating in some cases and never leaving the weld crater at the end of the weld. Put the craters in from each end and make sure to fill them. Fill in any undercut. Also if it's a repair like a crack through a bucket, make sure you get 100% penetration. It's best to weld one side of a beveled joint and then grind into the weld to clean steel from the other side. Sometimes you also have to consider the stresses created by welding. You have to allow large welded parts to move. Prebending and/or pre and post heat can help relief stress. If the pieces are held too ridged puts a lot of stress in the weld. When I had to weld the 1 1/2" thick bottom swing mount on my backhoe, I tacked it down about 30 deg's. from level before welding to allow it to cool and contract naturally and return close to level on cooling. Only when it was close while cooling off did I tack a brace to hold it level. If I had braced it in the final position and just welded it, it would be very susceptible to cracking because of all the stress created from the welding. It would be like a wound up spring ready to explode. Welds have to be allowed to expand and contract. There's lots of other techniques and tricks you can use too. If you posted some pics. of what you needed to weld or repair or of failed repairs we can offer some more specific advice on the best way(s) to hopefully have a successfull repair. I agree to keep the solid wire Mig away from heavy equipment repairs. It would be OK for 1/4" and under steel.

 

[Tugger2]

Myself and another guy welded the new lip on that shovel bucket in my picture back in 70s . It was a huge chunk of Manganese. We did run weedburners for preheating.And had Vibrators bolted on in various locations that ran all the time as we welded . Poured a lot of rolls of 3/32 stainless wire into that one.

 

[Welder Dave]

Manganese is kind of odd. Thick sections need to be hot to weld but can't get too hot or they'll break.

 

[henry.45]

Myself and another guy welded the new lip on that shovel bucket in my picture back in 70s . It was a huge chunk of Manganese. We did run weedburners for preheating.And had Vibrators bolted on in various locations that ran all the time as we welded . Poured a lot of rolls of 3/32 stainless wire into that one.

Impressive work! The use of manganese, weedburners, and vibrators for preheating and welding demonstrates a high level of skill and expertise.

 

[Welder Dave]

Some of it is just going by the best practices method. Unfortunately some equipment owners or repair people don't read up or research how to weld certain types of steel and just weld it the same as if it's mild steel. A former neighbor discovered 7024 runs really nice and makes a pretty bead. He was repairing the lifting lug on a wrecking ball. I had to tell him 7018 is a way better choice and a lot stronger. Also to pour the preheat to it and let it slow cool. He also told me to use some rods his friend got cheap at an auction, 1/4" 6010. Partially overhead on a loader bucket to boot. That's the rods we got so use them. Were more like gouging rods but I couldn't really tell him they were about the absolute worst rods to use. I was pretty early in my welding experience at the time.

 

[henry.45]

Interesting! Your neighbor prioritized 7024 for aesthetics, but 7018 is stronger and should be preheated. Using 6010 on a loader bucket isn't ideal due to its gouging nature.