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Thermal Spray Welding to build up way surfaces?

Spud

Diamond
Joined
Jan 12, 2006
Location
Brookfield, Wisconsin
I was wondering why the Thermal Spray Welding process isn't used to deposit metal on machine ways for rebuilding ; as opposed to using a product like Moglice ?

On a totally different note....
I was recently binge watching American hotrod episodes ; they sure use a lot of bondo to smooth out body panels prior to painting.It's easier than laboriously removing all high and low spots in the panels. I take it all the top builders including Chop Foose use bondo. Could Thermal Spray Welding be used to patch small holes in rusted out sheetmetal and chassis?



Oerlikon thermal spray welding
Thermal Spray Processes « Oerlikon Metco
 
I guess this totally depends on what surface you want to build up?? The moving surface or the non moving surface??

Why would you like to use a spray weld VS moglice or turcite??

I have quoted grinding jobs 2x in the past that had spray weld. but unfortunately the person who had the spray weld don't thought it would be a really great idea to coat the ways with a carbide RC 78 material. After coming to us for a quote, which then the customer said that 2 shops in Rockford tried to grind then realized it was 78 Rockwell and you needed a Diamond wheel.

I would stick with the method of machine/grind the parts, build up the moving part with turcite or moglice and finish grind/scrape.

What machine are you working on??

I am local to you and work with a local spray welder. We do have many items stray welded when customers request it.
 
I guess this totally depends on what surface you want to build up?? The moving surface or the non moving surface??

Why would you like to use a spray weld VS moglice or turcite??

I have quoted grinding jobs 2x in the past that had spray weld. but unfortunately the person who had the spray weld don't thought it would be a really great idea to coat the ways with a carbide RC 78 material. After coming to us for a quote, which then the customer said that 2 shops in Rockford tried to grind then realized it was 78 Rockwell and you needed a Diamond wheel.

I would stick with the method of machine/grind the parts, build up the moving part with turcite or moglice and finish grind/scrape.

What machine are you working on??

I am local to you and work with a local spray welder. We do have many items stray welded when customers request it.

Oh I am not looking to rebuild any of my machines ; my OP was just curiosity on whether the process was used.
 
I can instantly see the hypothetical benefits. If a lathe bed or a long mill table have a low spot in the middle of a few thou in a short section. Why bother lowering the far ends when the middle can be brought up.

The immediate issue is working properties, as said above, Not only if it can be ground effectively but can it be scraped easily. Will the border between base and sprayed matreial be troublesome.
 
It seems like the heat would cause warping on something long like a lathe bed.

There is also something called surfalloy or something like that that we used to re-surface v-blocks and other wear items and it don't seem to need so much heat to make the alloy stick. It can be applied form soft to very hard nearing carbide hardness.
 
It seems like the heat would cause warping on something long like a lathe bed.

That's my concern. If anyone has done something similar where it's a one-sided deposit, I'd really like to hear if they noticed warping or other stress. I've got a large Monarch lathe that I've thought of spray coating, and in my case I've considered building up both the ways and the bottom of the casting to try to even out the heat and stress buildup.

But Cash is almost certainly right, much easier to use a cold process than hot.
 
It seems like the heat would cause warping on something long like a lathe bed.

There is also something called surfalloy or something like that that we used to re-surface v-blocks and other wear items and it don't seem to need so much heat to make the alloy stick. It can be applied form soft to very hard nearing carbide hardness.

That is the beauty of spray weld-there is very little heat involved. That is why in the video they have the heat gun there, we cant see the numbers but normally under 300 deg.
 
I bought a spray weld kit a few years ago but have yet to try it out. The guy I bought it from told me that the powder is pretty expensive. I think the instructions said 400 degrees was the temp. for spray welding with my kit.

That is the beauty of spray weld-there is very little heat involved. That is why in the video they have the heat gun there, we cant see the numbers but normally under 300 deg.
 
I was looking on BidSpotter recently and there was this Metco Thermal Spray Welder. Not knowing what the process was I looked it up on YouTube and the 1st thing that came to my mind was whether such a process could be used for building up machine tool ways. I do have a small divot on the way of my Studer grinder but rebuilding that is not something I am going to do anytime in the near future.

I was also thinking whether this process could be applied to automotive restoration.
 
I had a W & S Turret lathe once and there was a short area up near the head-stock that was worn low. I think it was a # 5 and the bed was flame hardened. I saw a flame spray at a trade show and called the local rep and he came out and assured me "no problem" So we made an appointment for him to come and show me how on the job.

It was a total failure for the most part as the casting would absorb the heat before we sprayed. This guy said we needed to have a rose-bud plus the spray weld torch to keep the casting hot enough. his first application looked good, but when we tried to file and grind it...well it fell off, should have seen his eyes......then he tried again...he said the oil in the ways needed to be sweated out....next try we got the metal cherry hot...I told him this was it.

It stuck that time, but was rock hard and we had a terrible time grinding it. I would never try it again an am damn lucky we were able to salvage the machine. The customer never said a word....in the rebuilding business, "no news is good news". For all the labor of one of my men, I and buying the spray unit, gas and material used and then grinding it down we could have had the bed ground. Even if the newer technologies have improved spray welding on oily machine bed I would not do it. The spray weld on a small part is a big difference then a massive lathe bed. Rich
 
I was using thermal spray for numerous projects. It is a great process that can deposit different metals and ceramics on variety of substrates. As for rebuilding it has applications mostly to build up worn or damaged pats and sometimes for coating existing parts with harder metal. A common application is building up worn shafts, and I've used it in a number of instances. The build up is rather rough and not controllable to very close tolerances. The standard technique is to build up more than needed and then to bring the part to the correct dimension, usually by grinding. With round or flat surface it is easy to do on a cylindrical or surface grinder. In theory it could be used on a bed of lathe (for example) but this will mean a heavy build-up and complete re-machining of the bed in factory-like set-up. Not very practical, but not impossible.
 
I had some experience with it a few years back, not applying it, but machining the area back to size after it was sprayed on. My opinion of it is while it may be an ok fix in certain instances, it's not a cure all for sure. Like Rich said, lots of problems with adhesion. The sprayed on stuff is molten when applied, but the metal under it is not. Not very good welding practice, absolutely no penetration! A company that I did a lot of work for used it on everything. They did mostly repair work on industrial equipment, so they were constantly repairing worn out journals, bearings, slides and such. They didn't do any precision machining in house. Before they got the spray weld rig, they would send the worn out part to us and we would typically machine undersize and sleeve or bolt/braze/weld material in, or turn a journal undersize and make new bearing to suite or whatever conventional fix best fit. Then they started rough machining the parts themselves, spraywelding, and sending them to us to resize. Even when the stuff adhered well, it never seemed to stand up to use and we usually wound up doing the same repair again in short order. Like I said, I'm sure it has a use, but I don't think I want it on any of my machines ways, or on any part of my machines for that matter. To me, it's a couple of steps above JB Weld, maybe that's to generous.
 
Like Rich said, lots of problems with adhesion. The sprayed on stuff is molten when applied, but the metal under it is not.

One must differentiate between the various techniques of thermal spray. While flame spray systems might indeed have poor adhesion in some application, plasma spray is much more tenacious. Plasma is not only much hotter, but the material is fed as powder or liquid suspension and ejected with very high velocity. In some of my applications I did tests samples, sliced and polished and photomicrographed. There was a distinct mixing area between the substrate and the cladding where the substrate material surface melted.
The attached image is of molybdenum on stainless.

plasma.jpg
 
Rich pretty much summed it up, metallizing cast iron with flame or arc-wire spray isn't likely to work well at all. Both need some section thickness to work properly, and any feathered edge like you would have bringing the build up back down to the original unworn surface is gonna fail. Doing it with a cast iron flat is likely to all fail.

Old timey - eutectic, mogul and metco used to demonstrate the cold processes by spraying on a business card without charring or burning it. The bond mechanism is not considered chemical (fusion) to the substrate, it's mostly mechanical and needs a proper surface to work well.

I've used the flame and the arc-wire & while they are good for shaft repairs & coating things for harsh environments they are dirty. Pretty sure OSHA would want you pumping breathable air to anyone using them these days.

Plasma & HVOF coatings are very different beasts & expensive. You can thin coat the faces of internal combustion engine valves with those two if you want.

The section billzweig posted looks pretty much like arc-wire with nickel-aluminum at the bond line (no iron to digest). The hair on the top looks new to me though...

Matt
 
i would be concerned about bimetallic thermal expansion.
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basically i have often seen 2 different metal alloys bolted, welded, or sprayed together and if machined flat at a certain temperature when the room temperature changed and the different alloys expanded at different rates it cause the flat surface to curl.
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i had a linear rail with a capacitance sensor bolted to a concrete floor next to a 18 foot diameter 5 foot wide 20 ton cast iron wheel. it was set optically straight to within .001" and the next day when check before using to measure the cast iron wheel for rotational eccentricity we see the linear rail is curved.
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i notice it is a sunny day and we are under a skylight window. linear rail was set straight on a cloudy day and not so hot room temperature. so we come back the next day after when it is cloudy out and temperature is same as when linear rail was set straight and it is straight again. the cause was the concrete floor being more massive and heavy expands at a different rate then a steel linear rail of thinner thickness. since steel linear rail is bolted to cold concrete the linear rail when it expands has to go somewhere so it curves in shape
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usually we just remachine castings to remove worn section. most castings are worn less than .010" and remachinning usually is easier, faster and the most reliable. i would say average wear needing remachining is usually less than .004"
 
Just saw below video. They are using Metallisation to fill up small rust holes in autobody panels. Never seen any of the big name custom car / hot rod builders use this process. Anyone know if it is very very new?
 
I just wrote to FST and linked this thread, hopefully they will respond. It looks and sounds like the newer spray welding technologies might work on oil soaked cast iron machine tool ways. If it can be used as in the Cat engine it may work great on a W & S lathe bed. Rich
 
I have been spray welding for years.It is a great repair for a lot of situations. I don't think it would be good to use near any way surface because of the heat involved and what it will do to the iron. A cyl. head is a lot different than a cyl. grinder etc.

.002 tolerance is pretty far from .0002". Every situation is different but I would be reluctant to do it on a precision surface given what I know.

And for crack repair, anything other than a corner and you have to heat the whole casting up hold it there and cool it slow.
Or you will end up with a bigger mess than when you started.
 








 
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