BABBIT BEARINGS

[Vijay Deshpande]

i want to know how spray babbitted bearings perform under heavy load conditions in comparison with pored bearings
Vijay Deshpande

[bhellman]

i want to know how spray babbitted bearings perform under heavy load conditions in comparison with pored bearings
Vijay Deshpande

Hi, I have some info from the past:
Babbit spraying is difficult, due to all the dust developed. Depending on the size of the bearing, it may be rational to not make it by spraying, but by "welding". Very large bearings has succesfully been made by spraying in very well ventilated circumstances.
bhe

[Jim Weber]

i want to know how spray babbitted bearings perform under heavy load conditions in comparison with pored bearings
Vijay Deshpande

Hi, I have some info from the past:
Babbit spraying is difficult, due to all the dust developed. Depending on the size of the bearing, it may be rational to not make it by spraying, but by "welding". Very large bearings has succesfully been made by spraying in very well ventilated circumstances.
bhe

Hi,

I have lot old Metco data regarding spraying of Babbitt on bearings, and from what I have read it is superior to poured or welded Babbitt bearings. The microstructure of the thermal sprayed coating and the interspersed oxides provides better performance.??

There are several ways to spray Babbitt, but the least dusty is flame (combustion) wire, like a 12E or 14E. I have sprayed it a bit, and it really isn't that smoky with flame wire, but with the arc wire process it makes a real mess! If Make sure you use high-speed gears, because this wire moves very quickly through the gun, and your gas flow settings should be more fuel rich (reducing flame) than typical flame spray coatings. The goal is to have the Babbitt wire gets just soft enough in the flame so that the atomizing air sheds droplets off of the wire. Much less smoke and dust this way.

Here is a quick outline of the procedure to "Babbitt" a bearing using thermal spray;

1. Cleaning the substrate by sanding or very fine grit blasting. It is not necessary to rough blast with grit.

2. Heating the substrate to ~450F/230C and apply a water based flux and tin powder mixture.

3. Using a stainless steel brush, tin the entire surface. (The entire surface of the sprayed area should have a shiny, wet, brush applied tin coating).

4. While the substrate is still hot (the tinned surface is shiny), spray the Babbitt coating.

This coating will have much higher bond strength than a coating applied to a grit blasted surface. It is a metallurgically bonded (brazed/soldered) coating.

You should be aware of the hazards of spraying tin. Babbitt is ~90% tin. Tin and tin oxide dust, when starved of oxygen, will react and heat up, possibly causing a fire. In an duct extraction system, even a layer of tin 0.5" deep has been known to react. I have experiences with several tin fires. You need to make certain that exhaust and ducting is engineered to minimize tin hazards. Good housekeeping is key to minimizing hazards when spraying tin.

If someone would like any of these old documents, I can scan them and send them to you.

Warm Regards,

Jim Weber

[Gordon]

Hi Jim

to the Surface Engineering Forum and thank you for your contribution.

[imran-elahi]

i want to know how spray babbitted bearings perform under heavy load conditions in comparison with pored bearings
Vijay Deshpande

Hi, I have some info from the past:
Babbit spraying is difficult, due to all the dust developed. Depending on the size of the bearing, it may be rational to not make it by spraying, but by "welding". Very large bearings has succesfully been made by spraying in very well ventilated circumstances.
bhe

Hi,

I have lot old Metco data regarding spraying of Babbitt on bearings, and from what I have read it is superior to poured or welded Babbitt bearings. The microstructure of the thermal sprayed coating and the interspersed oxides provides better performance.??

There are several ways to spray Babbitt, but the least dusty is flame (combustion) wire, like a 12E or 14E. I have sprayed it a bit, and it really isn't that smoky with flame wire, but with the arc wire process it makes a real mess! If Make sure you use high-speed gears, because this wire moves very quickly through the gun, and your gas flow settings should be more fuel rich (reducing flame) than typical flame spray coatings. The goal is to have the Babbitt wire gets just soft enough in the flame so that the atomizing air sheds droplets off of the wire. Much less smoke and dust this way.

Here is a quick outline of the procedure to "Babbitt" a bearing using thermal spray;

1. Cleaning the substrate by sanding or very fine grit blasting. It is not necessary to rough blast with grit.

2. Heating the substrate to ~450F/230C and apply a water based flux and tin powder mixture.

3. Using a stainless steel brush, tin the entire surface. (The entire surface of the sprayed area should have a shiny, wet, brush applied tin coating).

4. While the substrate is still hot (the tinned surface is shiny), spray the Babbitt coating.

This coating will have much higher bond strength than a coating applied to a grit blasted surface. It is a metallurgically bonded (brazed/soldered) coating.

You should be aware of the hazards of spraying tin. Babbitt is ~90% tin. Tin and tin oxide dust, when starved of oxygen, will react and heat up, possibly causing a fire. In an duct extraction system, even a layer of tin 0.5" deep has been known to react. I have experiences with several tin fires. You need to make certain that exhaust and ducting is engineered to minimize tin hazards. Good housekeeping is key to minimizing hazards when spraying tin.

If someone would like any of these old documents, I can scan them and send them to you.

Warm Regards,

Jim Weber

Hi jim
Its imran new participent, I really appriciate your way to handle the babbit coatings but one thing in this method is to keep remmember. That is this methode is only feasible for those bearings which we have to coat them from their base material. If we have a bearing which is only one millimeter over from its equired size and the babbit thickness in the bearing is about 20mm then what should we do in this aspect.
Waiting for positive answer
Imran Elahi

[Arturas]

Hello,
I also make some experiments with babbit spraying several years before. As I remember there were some problems with coating: at the beginig the quality of a coated surface looked quite nice , but with increasing thickness showed "columnar structure". And especially when we performed spraying of internal surface. I thought that it were due to big quontity of dust in spraying zone , overheating of coating during the spraying time.
Maybe some one can comment me it????
If it is possible Jim Weber, maybe You can send these documents about spraying of babbit . It is very interesting for me how Metco solved these problems
Best regards
Arturas

[bhellman]

i want to know how spray babbitted bearings perform under heavy load conditions in comparison with pored bearings
Vijay Deshpande

Hi, I have some info from the past:
Babbit spraying is difficult, due to all the dust developed. Depending on the size of the bearing, it may be rational to not make it by spraying, but by "welding". Very large bearings has succesfully been made by spraying in very well ventilated circumstances.
bhe

One comment; using Al-bronze as a bond coat will easily tell any failures in he babbitt coating later on.
bhe

Second comment:
It seems that the interest in spray made babbitt bearings have lessen in the past decades. Would be interesting to hear any comments on why this have happened.
bhe





I have lot old Metco data regarding spraying of Babbitt on bearings, and from what I have read it is superior to poured or welded Babbitt bearings. The microstructure of the thermal sprayed coating and the interspersed oxides provides better performance.

There are several ways to spray Babbitt, but the least dusty is flame (combustion) wire, like a 12E or 14E. I have sprayed it a bit, and it really isn't that smoky with flame wire, but with the arc wire process it makes a real mess! If Make sure you use high-speed gears, because this wire moves very quickly through the gun, and your gas flow settings should be more fuel rich (reducing flame) than typical flame spray coatings. The goal is to have the Babbitt wire gets just soft enough in the flame so that the atomizing air sheds droplets off of the wire. Much less smoke and dust this way.

Here is a quick outline of the procedure to "Babbitt" a bearing using thermal spray;

1. Cleaning the substrate by sanding or very fine grit blasting. It is not necessary to rough blast with grit.

2. Heating the substrate to ~450F/230C and apply a water based flux and tin powder mixture.

3. Using a stainless steel brush, tin the entire surface. (The entire surface of the sprayed area should have a shiny, wet, brush applied tin coating).

4. While the substrate is still hot (the tinned surface is shiny), spray the Babbitt coating.

This coating will have much higher bond strength than a coating applied to a grit blasted surface. It is a metallurgically bonded (brazed/soldered) coating.

You should be aware of the hazards of spraying tin. Babbitt is ~90% tin. Tin and tin oxide dust, when starved of oxygen, will react and heat up, possibly causing a fire. In an duct extraction system, even a layer of tin 0.5" deep has been known to react. I have experiences with several tin fires. You need to make certain that exhaust and ducting is engineered to minimize tin hazards. Good housekeeping is key to minimizing hazards when spraying tin.

If someone would like any of these old documents, I can scan them and send them to you.

Warm Regards,

Jim Weber

Hi jim
Its imran new participent, I really appriciate your way to handle the babbit coatings but one thing in this method is to keep remmember. That is this methode is only feasible for those bearings which we have to coat them from their base material. If we have a bearing which is only one millimeter over from its equired size and the babbit thickness in the bearing is about 20mm then what should we do in this aspect.
Waiting for positive answer
Imran Elahi

quote=imran-elahi]
Hi, if you could provide us with a skiss on your object, it would be much easier to confront the problem.
bhe

c

[cristi.genes]

Hi Everybody,
I read your answers on babbit topic and I saw you have a lot of practical experience in babbit applications. I'm trying now to apply on a big bush from a cement factory (crusher) but I have big problems with adherence. I understand from your advices that before spraying babbit to increase the adhesion is better to preheat the bush. OK total agree with you but I must spray on both sides of the bush and this means that the depot on both surfaces must be made in the same time after preheating. Correct?
Circumstances:If I have to repair only the inside surface how will I proceed? Because if I will preheat at 230C this will affect the outside layer. Or not?
If I make a thread this will increase the adhesion? Take in consideration that the bush have the outside axis eccentrically and inclined beside internal axis. The outside diameter is 900mm and inside diameter 700mm.
Regarding the water based flux and tin powder mixture can you be more specifically, how are these two components used? If you need more details please contact anytime. Thank you.

[Jim Weber]

Hi Everybody,
I read your answers on babbit topic and I saw you have a lot of practical experience in babbit applications. I'm trying now to apply on a big bush from a cement factory (crusher) but I have big problems with adherence. I understand from your advices that before spraying babbit to increase the adhesion is better to preheat the bush. OK total agree with you but I must spray on both sides of the bush and this means that the depot on both surfaces must be made in the same time after preheating. Correct?
Circumstances:If I have to repair only the inside surface how will I proceed? Because if I will preheat at 230C this will affect the outside layer. Or not?
If I make a thread this will increase the adhesion? Take in consideration that the bush have the outside axis eccentrically and inclined beside internal axis. The outside diameter is 900mm and inside diameter 700mm.
Regarding the water based flux and tin powder mixture can you be more specifically, how are these two components used? If you need more details please contact anytime. Thank you.

Hi Cristi,

Sounds like a fun job!

Tinning the surface is a good idea, but not absolutely necessary. To increase the adhesion, you could do the following;

1. Use a very coarse sprayed bond coat of either Molybdenum or nickel-aluminum powder cored wire. These are "self bonding", meaning they will sort of micro-weld to the surface, and their rough surface gives a good anchor for the Babbitt.

2. Make sure the surface is abrasive blasted with clean grit; garnet or AlO2 is preferred.

3. Arc or flame spray wire? Or are you using flame spray powder? Flame spray wire will be best, but make sure he flame is fuel rich (reducing) so that the oxides are minimized.

4. When applying the first coating pass, try to angle the gun in such a way that the spray dust goes over the area just coated and not the uncoated surface. This way, spray dust will not interfere with the bond of the first pass.

If you decide to tin, your surface needs to be smooth but sanded clean (mechanically clean), then solvent cleaned (chemically), and then you can preheat only the surface to be tinned.

Remember, the tinning is done at a pretty low temperature, so you can just heat the surface with a large rosebud torch and just tin the area around the torch and not the entire shell. It takes a while for heat to get complexly through the shell.

If you are worried about the other side melting, just wrap a wet towel around it to keep it cool.

You can use a flux similar to this one;

(link dead)

Or better yet, this E-127 tinning paste specifically used for tinning bearing shells;

(link dead)

(link dead)


The flux is washed away with water after you are done tinning. Make sure you wash the entire shell.

Just prior to spraying, start heating the surface again (you will see the tin go from dull to shiny) and apply your first coating pass. It will slightly melt into the wet, tin surface. You can use the rosebud torch just ahead of the spray gun to maintain a wet surface. Again, if you are worried, keep a wet towel wrapped around the other side of the shell to keep it cool.

After the first pass, there is no need to keep the shell hot.

Hopefully this helps you. Send some photos when you have a chance.

Regards,

Jim Weber



James K. Weber Consulting LLC
114 North Clinton Ave.
Bay Shore, NY 11706
(631)767-8099