MIG brazing to build up worn surface?

OK, be nice. I recently repaired some cast iron by MIG brazing it. Quite large sections. Very little heat input at all, so I don't think warpage would be an issue.

So, does anyone think this could work on machine ways? MIG braze, machine, and then scrape. I used silicon bronze, but many different types are available. I milled some and it cuts quite nicely. Almost a mirror finish.

Thoughts?

Tim

I think it's possible in theory but impractical in actual practice. So, imagine you've got a flat way (easy surface) that's original on both ends but work .010 in the middle. Then, making an assessment you find where the wear starts and mark an area in the middle, perhaps on third to one half the length of the way that needs to be built up. You get your equipment and have perhaps 30 to 40 square inches to cover with new material. Put it all on. But you're not putting .012" in the worst affected area, you're probably puddling on .030 or more. So the next thing you need to do is machine off the excess down to maybe just a couple thousandths over what's needed and begin to scrape that down.

It sounds like a lot more work and opportunities for things to go sideways compared to taking a deep breath and approaching it traditionally. If you want to try it I wouldn't hold you back, just like to hear your actual experience in case I'm wrong.

Oh, and how does the new bronze surface wear compared to the cast iron.

I'd be interested in knowing more about the MIG brazing process, I've heard of TIG brazing, but MIG brazing is a new one for me.

Timboberonion said:

OK, be nice. I recently repaired some cast iron by MIG brazing it. Quite large sections. Very little heat input at all, so I don't think warpage would be an issue.

So, does anyone think this could work on machine ways? MIG braze, machine, and then scrape. I used silicon bronze, but many different types are available. I milled some and it cuts quite nicely. Almost a mirror finish.

Thoughts?

Tim

Click to expand...

Interesting idea.
Im thinking if youd attempt this youd be better off doing the guided surface. Ie:- Scrape/grind a lathe bed as per norm, mill out/braze up the saddle etc. Even though its a relatively low heat process theres still a lot of potential for things to move imo, might well cause more problems than its worth. In a less sensitive situation I think its a cool idea, just make sure youve got your process down with a good strong joint and go for it.

I second TGTool skepticism and, I'm afraid, there is another potential issue at the transition between cast iron and bronze: it doesn't matter how hard you try, you'll have a little gap forming between the two metals due to different wear properties. And those gaps are great pockets for all the grit to accumulate in and grind the mating surface.

Paolo

Timboberonion said:

OK, be nice. I recently repaired some cast iron by MIG brazing it. Quite large sections. Very little heat input at all, so I don't think warpage would be an issue.

So, does anyone think this could work on machine ways? MIG braze, machine, and then scrape. I used silicon bronze, but many different types are available. I milled some and it cuts quite nicely. Almost a mirror finish.

Thoughts?

Tim

Click to expand...

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for certain shapes like a shaft where a plating or brazing or plasma spray coating is applied evenly it often will work with some limitations.
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BUT when coating like brazing is applied on one side thermal expansion differences cause a bimetalic effect and warpage changes at different temperatures. thus a part can be straight and flat at 70F but warped at 65F or 75F.
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cold rolled steel part thats all steel but the skin is work hardened. when material is removed on one side the stretched metal skin becomes uneven thus why when unclamped or unchuck a part goes bong or warps.

I've worked on a few machines in years past were scores in the ways had obviously been repaired by means of a brass or phosphor bronze powdered metal spray. You could see the overspray on non essential areas of the castings. The repairs worked very well with no signs of drop out. How the repairs were achieved I don't know.


Regards Tyrone.

Nightmare!

I have seen where people weld cast iron ways plus I spray welded a Hardened W&S Turret Lathe square way. Ways, especially old oil soaked worn and galled ones. I have brazed gibs by extending the wide end to lengthen it, then milling it. That worked ok, but the gib was thin and was not scored. When a gibs were scored we made or bought new ones.
Never saw a scientific study on this though, have you?

The ways I saw arch welded were on Big 12" wide Boring machines like G&L', Lucas, etc. I was once called to look at a G&L 3M had, They had another rebuilder weld the scores (arc) and it was peeling up because I assumed the oil soaked ways and heat suck (drain)could not be welded and as the saddle ran over the peeling weld, it would jam up the machine. I told them to get the other guy to fix it as I Saw a Nightmare trying to fix that mess. I have no clue if it was fixed or scrapped. (Scrapped to the junkyard, not scraped) The only cure I could see was to have the bed planned, bronze wear-strips, etc. Costing 3M thousands of dollars again.

I had a spray welder salesman convince me I could spray weld ways to fill worn area's. I had a company call me saying their W&S number 5 Turret Lathe front box way was worn up near the chuck and when the used a spade drill to drill a hole the saddle would move over.

I invited the salesman to come and show me how it worked and we bought the unit that we attached to our acetylene torch. The issue we had was the machine was huge casting and it sucked the heat away from the heated area. He kept having us pre-heat the area with a rose-bud and after it got cherry red we switched the torch head to the sprayer. Then spray, most of the time it would peel off and we have to do it again. Talk about embarrassed as we were doing it inside the customers machine shop and they as I were getting scarred the machine would warp.

Then after it stuck it got rock hard and we had to drum sand (grind) the weld and it was a NIGHTMARE. I did not have a scientific study by the way, proving it was a Nightmare, just the experience that it was. I suppose a thin piece like a gib would be fine, but a large oil soaked casting that sucks the heat so fast it would be a nightmare and not stick for long.

brush electroplating since before WW2 is a way to apply different metal platings usually at room temperature to buildup material in spots. sort of like a electric magic marker. dip electrode holder in chemicals and rub on electrically connected part.
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various metals like copper, nickel, cobalt, gold, etc has been plated on printing press rollers to fill scratches and grooves for over 70 years. parts that are machined after plating are normally ground as lathe turning and milling might peel off the plating like is was a type of metal foil tape.
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kind of a slow process i often took over a hour to fill a scratch or pit in a printing press roller with gold and sanded it smooth to the nearby existing chrome plating. point was to fill scratch or pit holding ink that was transfering or printing when you didnt want it too
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on a slowly turning lathe part often part has a plastic tray under it and a small pump is continuously pumping chemicals as the electrode holder is in contact where plating is being applied. sometimes chemicals are heated so plating goes faster. caustic and hazardous chemicals and a bit of a job cleaning up.
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many larger cylindrical rollers like 18 feet in diameter (30 tons) a copper plating many mm thick is applied to cast iron wheel and its later ground to true cylindrical shape and eventually nickel and chrome plating is applied for corrosion resistant hard coating it. copper used cause it plates fast and easy to machine and less fumes. chrome plating gives off toxic fumes not done like it used to be. epa requires pollution control equipment.
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the whole point of gold plating to fill scratches is removing a 30 ton 18 foot diameter cast iron wheel and shipping it out for replating cost millions and takes over a month. thus why its cheaper to pay a few $1000. for a brush plating repair thats often done on the same day.
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many machines had their ways chrome plated in the old days. chrome is harder than cast iron and corrosion resistant. usually the plating underneath the chrome was ground flat straight first so the chrome applied was flat and straight. often chrome is not that thick talking .0002 to .0020", thicker the chrome the longer it takes to apply. was not unusual to apply chrome at night when nobody around to breath the fumes. plating thickness was what ever you got plating overnight. epa doesnt allow hexavalent chrome fumes without some very expensive pollution control equipment now a days

Richard King said:

Nightmare!

I have seen where people weld cast iron ways plus I spray welded a Hardened W&S Turret Lathe square way. Ways, especially old oil soaked worn and galled ones. I have brazed gibs by extending the wide end to lengthen it, then milling it. That worked ok, but the gib was thin and was not scored. When a gibs were scored we made or bought new ones.
Never saw a scientific study on this though, have you?

The ways I saw arch welded were on Big 12" wide Boring machines like G&L', Lucas, etc. I was once called to look at a G&L 3M had, They had another rebuilder weld the scores (arc) and it was peeling up because I assumed the oil soaked ways and heat suck (drain)could not be welded and as the saddle ran over the peeling weld, it would jam up the machine. I told them to get the other guy to fix it as I Saw a Nightmare trying to fix that mess. I have no clue if it was fixed or scrapped. (Scrapped to the junkyard, not scraped) The only cure I could see was to have the bed planned, bronze wear-strips, etc. Costing 3M thousands of dollars again.

I had a spray welder salesman convince me I could spray weld ways to fill worn area's. I had a company call me saying their W&S number 5 Turret Lathe front box way was worn up near the chuck and when the used a spade drill to drill a hole the saddle would move over.

I invited the salesman to come and show me how it worked and we bought the unit that we attached to our acetylene torch. The issue we had was the machine was huge casting and it sucked the heat away from the heated area. He kept having us pre-heat the area with a rose-bud and after it got cherry red we switched the torch head to the sprayer. Then spray, most of the time it would peel off and we have to do it again. Talk about embarrassed as we were doing it inside the customers machine shop and they as I were getting scarred the machine would warp.

Then after it stuck it got rock hard and we had to drum sand (grind) the weld and it was a NIGHTMARE. I did not have a scientific study by the way, proving it was a Nightmare, just the experience that it was. I suppose a thin piece like a gib would be fine, but a large oil soaked casting that sucks the heat so fast it would be a nightmare and not stick for long.

Click to expand...

This process doesn't involve any sort of gas torch, only a MIG process. The heat is very localized. The most common use is on body panels to minimize warpage of the thin sheet metal, and for that, it works very well.

I wouldn't ever consider getting a gas torch anywhere near machine ways, let alone to get them to brazing temperature. MAYBE to burn off some oil, though there are some exceptional cleaners available.

Like I said, I'm just wondering if it could work. The only real way to do it would be to try it as an experiment. It could be done in very small sections and allowed to cool completely between build-ups. I might take a chunk of Dura-Bar and do just that.

As for longer sections, that would probably get interesting in a big hurry!

Tim

Timboberonion said:

This process doesn't involve any sort of gas torch, only a MIG process. The heat is very localized. The most common use is on body panels to minimize warpage of the thin sheet metal, and for that, it works very well.

I wouldn't ever consider getting a gas torch anywhere near machine ways, let alone to get them to brazing temperature. MAYBE to burn off some oil, though there are some exceptional cleaners available.

Like I said, I'm just wondering if it could work. The only real way to do it would be to try it as an experiment. It could be done in very small sections and allowed to cool completely between build-ups. I might take a chunk of Dura-Bar and do just that.

As for longer sections, that would probably get interesting in a big hurry!

Tim

Click to expand...

Soak the Dura Bar in a bucket of oil for a month prior. I saw you said low heat but I figured people would think of the other methods too. A good teaching moment as Tom's info on plating.

My old father built up a dovetail on a compound slide with mig brazing probably thirty years ago. Even as a schoolboy I thought he was being a bit rough so to speak but it came out perfect! It was a chunk not a built up strip so not as scary as using as a turcite substitute