Re-babbitt bearing procedure

I believe the procedure for this may still be published in Machinery's Handbook, made available through Industrial Press, the publisher. I know that it was in editions of the past.

While it is hard for some to believe, there are many of those bearings out there, and they do require recasting and subsequent shimming and fitting from time to time. It reminds me of questions when someone sees my collection of bearing scrapers "What are those weird-looking things, some sort of Medieval tool." To of course my reply is "Yes they are!"

Ing. Robert Forbus

Try eBay in the category of books, machinery, industrial process, bearings, babbit and so on. I have a very good book on this unfortunately it's in storage.

Good luck,

Bob

Yes, the alloy is similar to soft solder, and it can be repaired with a soldering iron. You need specific babitt alloy, and its flux. Clean the bearing shells, and then tin them using the flux, some heat, and the babitt bar. Wipe the shells slick when hot with a dry rag.

Casting is done by melting the alloy bars in a "pot" using a flame source. The pour is made when both the shells are heated and the metal is hot enough to pour. Puddling with an iron is helpful to dispel porosity. Touching up the surface with an iron can aid in preventing surface voids when roughing in the shells to tolerance, prior to final finish.

There you have it.

Kent White

www.tinmantech.com

Loved your question--brought back a memory. I remember watching my father repair a bearing on some sort of farm implement years ago. He hammered and scraped the old bearing material out of the end bells and polished the shaft with a strip of crocus cloth. Then he wrapped the shaft with a piece of linen-based paper and poured the molten babbitt into the bearing shell with the shaft in place. the carefully-wrapped paper prevented the babbitt from siezing the shaft and provided a few thousandths of clearance. This of course was not a very sophisticated piece of machinery, nor was it intended to run at high rpm, but many of those old implements were designed to be repaired on the farm in just such a fashion. I remember being very impressed!

Lindsey Publications used to do a wonderful job of documenting these older technologies. Perhaps they have a website. Worth checking out.

Lonnie

The old standard method of re-babbiting bearings involved coating the shaft with a thick coating of lampblack (soot) from an oil lamp held close to the shaft. The paper idea expressed by Lonnie sounds like a good substitute, even if the paper turns to carbon as the babbit is poured.

Then the bearing halves were separated, the shaft cleaned, and the final clearance set by scraping the babbit (with a tool resembling a triangular file without teeth, but with sharp 60 degree corners). This procedure was used in everything from late 18th century gristmill shafting to model T Ford crankshaft bearings. In line shafting applications, most often the bearing cap was held by four bolts which were tightened periodically to make up for wear before new babbit was poured. As stated in other postings, the bearing caps were tinned before the pour to assure adhesion of the babbit.

Today, it would appear that Kapton film on the journal would make a pretty good spacer for setting the initial clearance. There will be some scraping required where the Kapton film seam is.

BernieK

There are a number of web sites that discuss the procedure, many from antique machinery and blacksmithing sites and a few from babbitt suppliers. Most of the previous posters describe the process fairly accurately, the seb sites will have more detailed descriptions. Do you know what type of babbitt alloy was originally used? This could affect the success of your application.

Take a look at

lindsaysbks.com

Have fun.

Sir,

I want to compliment you regarding your discussion of the re-babbitt bearing procedure. I do have a problem with my 1930 model a rear main seal leaking.

Your discussion is well thought and well provided. If you have an opportunity, may I ask your advise as to where to have this procedure done in the Columbus, Ohio area or perhaps send the block to someone.

Respectfully, Chip White

email: chip.white@flightsafety.com

You should never use your corporate e-mail address in personal correspondence. It is very unprofessional and most probably a violation of corporate policy.

Given what is known about FlightSafety's strict corporate policies, your position may be in severe jeopardy.

probably Alfred is not asking for repair of somewhat historic babbitt bearings but modern/actual machines bearings (you may believe it or not, babbitt or slide bearings keep running the biggest machines in all fields of industry and especially for power generation, what roller bearings are not able for ...).

For modern/actual slide bearings the bearing clearance and other features are ruled and the load capacity can be calculated for many specific designs.

Possible methods for babbitting depends on the machine type. For instance: bearings for a crank-shaft have (about) nothing to do with bearings for other rotating machines (e.g. electrical machines). The latter using babbitt of Sn or Pb base - bonded to a thick-walled and typically split steel body (the "shell"). This kind of bearing shells are made today in two basic processes:

- centrifugal moulding for productions in large numbers

- a welding procedure - for manual hand craft work (some say solder work).

In earlier times common cast procedures (sand-mould) were done as well, but for bigger bearing sizes the quality is bad because the cooling down process can't be controlled as required and therefore the metall structure and features would vary a lot within one item.

Repair of babbitt needs to be done with the original babbitt aloy - if the original alloy wasn't removed completely. Following procedures most typical are used for repair:

- local and/or full welding/solder proces for local built-up of fresh material or for replacing all the babbitt (see procedures for new bearings)

- matal spraying (flame spraying)

- centrifugal moulding (often not possible because of holes and grooves in the bearing body where the melt can escape - those holes and grooves have been machined after the original babbitting).

As said before, centrifugal moulding is used for bearing productions in large numbers (expensive machinery), and not suitable for occasional use. For occasional use modern metal spraying equipment might be more useful.

Advantage of metal spraying: done well low heat impact to shell minimises risks for thermal distortions, which can be a big problem for the function of slide bearings.

Production equipment often can be used for repair of other equipment as well, e.g. shaft repair, coating, etc.

Disadvantage of metal spraying: the babbit does not bond at shell body as good as the original babbitt. However, done properly the bonding is sufficient for most rotating eqipment. I would not recommend this method for bearings under high dynamic stress or under very high operating temperatures (turbo machinery, for instance).

For centrifugal moulding and metal spraying the equipment (and knowledge for using it) can be bought at the markets. Instead of your own investment there are many companies in the world providing bearing babbit repair in professional manner.

By the way: if the application was designed well and maintenance provided as recommended a slide bearing should not fail. A slide bearings lifetime thoretically is unlimited. The lifetime is limited by start and stop procedures (periods of mechanical wear from shaft at babbitt surface) - and oil flow/oil quality in foreground.

On the other hand: repaired poor, the next break down of the bearing already is programmed!

Hope, this is a piece of useful information - even if late.

Albert

Hello, I poured babbitt bearings for about 20 years, and did thousands of engines. If you email me and tell me what you are tryin g to do I will help you. Thanks, Larry Bunch LDB.3@NETZERO.COM

Dear Mr. Larry Bunch,

Have you poured turbine bearings also. I intened to pour a bearing with 84 % Tin. Can you please advise me on dos n donts and what tempretures to be maintained for Babbit as well as bearing shell. Shell is 200mm dia. and final bore size after babbitting shall be 160 mm dia. Babbitt lining shall be 1.5 mm thick. Also please advise me what cooling arrangement is to be made. Shall appreciate your guidance pl.

Best regards,

Karan

Dear Mr. Larry Bunch

We have a problem with re-babbitting our bearings where the shells are made out of cast iron. As you know, the graphite in cast iron makes the bond between the shell and the buffer layer of Tin very weak. Could you please help us with any means of improving the bond strength?

thanks and regards

Tissa

Dear Tissa,

If you want to get a good bond onto cast iron Shot-Blast the shells using Chilled Iron shot, (size Grade7. or there abouts if I remember correctly).

The blasting nozzle should be kept perpendicular to the bore surface at around 90 psi.

The chilled iron shot will massage the surface of the cast iron removing any surface free graphite and refining the surface which will now be mainly iron.

The basting pressure should be sufficient to crack some of the particles of Chilled Iron Shot, producing some sharp edges to the shot,cutting into the bearing bore surface. and producing a good mechanical key to the surface as the grit is recycled.

The grit should be kept dry and corrosion free. It should not be recycled too often as it picks up the free graphite and deposits it back onto your nicely prepared bearing surface!.

The bearing shell is now ready for retinning, (this should be done within 4 hours of shot blasting )the surface should be fluxed with killed spirits and immersing in a tin bath if you have one !

If you dont have access to a Tin Bath, specialist Tinning paints are available. I have used many different makes , but one of the best is manufactured by Castolin Eutectic and is called Tinweld 1.

This is pure tin paint they have another one called Tinweld 2 which is an alloy of Tin/Lead.

For most bearing applications including cast iron use Tinweld1. the tin paint is brushed onto the surface requiring tinning , and the bearing gently heated with a gas torch.Ensure the gas flame is slightly carburising and not oxidizing! The paint will melt and Tin the surface ready for rebabbitting.

Incidently you will be aware that the final bearing bond will only be as good as the preparation. If the bearing you are trying to whitemetal line is a used one then it is very important to remove all traces of oil contamination that may be present in the shell particularly if it is a casting as porosity is virtually always present.

To ensure the are no oil residues present heat the shell gently using a gas torch until any oil is burnt off. This should be done before shot blasting the shell ,as I have described.

Naturally the best method of relining with Babbitt is by centrifugal lining, but we dont all have access to such machines.

Next would be static pouring or "puddling".with the whitemetal pured into a half mould whilst the bearing stands on its end face.allowing the shell to cool carefully from the bottom up and from the outside diameter.using a gas torch and a stainless steel rod puddle the cooling front up from the bottom of the bearing. The gas torch being used to ensure the top end face of the bearing is the last area to go solid. By this unidirectional cooling you will achieve a good bond with minimal porosity.

Depending on the size of the bearing I have successfully lined bearing shells using a gas torch, either Oxy/Propane or Oxy/ Acetalene. Oxy /Propane give a slightly cooler flame and is a little easier to control.

Cast some sticks of Babbitt to use as filler rods,a length of angle iron makes a reasonable mould.

The process consists of locally heating the tin on the surface with the gas torch until it melts, dip the filler rod into the molten tin on the surface as if you were brazing. Start in the crown of the bearing and make your bead of whitemetal down the axis of the bearing.Repeat the process with another bead alongside the first, fuzing this bead into the first.

This process is repeated until all the bearing surface is covered.Second or third coats may be neccessary to build up the thickness you require.It is essential that each coat is fused into the previous and that the first coat is deposited into the tinning surface when it is molten.

If you position the bearing on your bench so that each run is horizontal you wont be fighting gravity, and with luck you molten babbit wont run off!

lastly check your bond using a dye penetrant check around the bond line,

If its "On Bond"around the edges its a reasonable chance it will be bonded elsewere!!!

Good Luck

Very good response. The killed spirits is muriatic(hydrochloric) acid that has been made neutral (killed) with zinc grits or powder. Take care if you use zinc powder, as it boils up fast with fine zince powder. In essence it is ZnCl2 in solution, a good flux.

By carburizing, read reducing, the inner part of the flame and lean it a little so it is bright yellow with late burning carbon from the gas being short of air

Tissa,

We are a babbitt bearing repair company and rebabbitt many cast iron shells while obtaining bond with our process which we protect. We would be pleased to work with you on your babbitt bearing requirements. Please respond if I can be of assistance.

Dear Sir,

I would like to know that, is this possible with out removing babbit material from bearing shell ,can we achive the babbiting by static casting to increase thickness,

if yes please brief the procedure.

thanking you,

M.Javed

Javed,

Please let me know if we can be of assistance. Our company repairs babbitt bearings daily, static casting, spin casting, and machining back to OEM specifications. Please reply if I can help.

Hi, friend,

I am also looking for similar info on babbitting procedure pl . Procedure shown is ok but critical data like what tempretures for shell and babbit to be maintained. Tinning procedure to be adopted before pouring the molten metal and then how to go about subsequent cooling of the bearing. Such details are to my mind are very important particularly for high speed bearings. any info pl ? thank you.

Karan

Most rebabbitting companies have strict controls in which they have developed and perfected for different base metal alloys. Our company performs rebabbitting, static casting and spin casting of bearings for repairing existing bearings, then machining them to correct size. If we can be of assistance, please respond and let me know.

YOU CAME IN LITTLE LATE. THIS WAS AN URGENT JOB WHICH HAS SINCE BEEN DONE. THANKS ALL THE SAME.

KARAN

you can puddle the bearing with a tourch and babbitt wire, Make sure you melt the babbitt

first before you stick

make sure you tin up the halfs first

Hello ,

I found this discussion about sliding bearings. I am working in thermal spray field and it would be nice to hear opinion about thermal spraying babbit on old weared out (0.1mm) casted babbit layers

Arturas

i was explaining the procedures for scraping and shaping a main line shaft bearing for an aircraft carrier and this feed was very helpful the information i found in this feed was very valuable to me thx to everyone involved in writing it

MM1 USN Retired

Brofeets