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Split Bearing spacer

Split Bearing spacer

Split Bearing spacer

(OP)
I am a machinist that is working for a plant mechanic and a turbine mechanic I am machining a bearing spacer to the dimension they have specified this is a split spacer that appears to be soldered together for final machining. the question is what is the proper or recommended way to break the solder joint? would like to know what ingersol recommends but nobody can tell me. but they expect me to split it for them. Anyone out there having done this before and could give me some insight would be appreciated.

RE: Split Bearing spacer

I don't know what they do now, but in the 20th century, some outboard motors used 'cracked' connecting rods.

I.e., the rod was machined complete with an integral cap, with the big end bore finished to act as the outer race for a needle bearing setup. Integral here meaning that the cap was forged as part of the rod.
Additionally, the cap bolt holes were bored, threaded and counterbored.
In addition to that, the thrust faces of the big end were V-notched radially at what would eventually become the rod/cap separation line, using a cutter that left a sharp root.
Then the rod and cap were each stamped with a number, to matchmark them.
Then, the rods were chilled (think liquid nitrogen),
the rod cheeks were clamped in a fixture,
and a big fast moving power hammer struck the rod cap and knocked it off to the side.
Thereafter, that rod and cap stayed together forever, and had to, because the brittle fractured surfaces didn't match any other rod/cap pairs. When the matchmarks were aligned and the bolts were tight, the fracture surface became invisible.

You might be able to find more info by searching for 'cracked rod' at sae.org.


Something like that should work if your spacer is made from a material that can be made brittle, e.g., with very cold temperature.



But I'm thinking that, if your machining removes the solder from everywhere but the joint, it may be possible to fracture the solder by applying tension to the two halves with a pair or bore-shaped shoes, and jacking them apart, with jackscrews or hydraulics.

It also might be possible to remove the solder with 'Soder-Wick', a real product comprising fine copper braid and flux, which removes _most_ of the solder from a joint with a little heat. It takes practice to do it well.


Can you afford to make some test pieces to work out your process?

Mike Halloran
Pembroke Pines, FL, USA

RE: Split Bearing spacer

I have not experaniced anything like what you mentioned. Even though I can't reply how to proceed, could you provide a more detail discription?

RE: Split Bearing spacer

(OP)
This is a 6" dia. plate with a 2 3/4" hole about 3/4" thick it goes behind the thrust bearing to set the thrust clearance of the rotor of a steam turbine. It is split to install around the shaft has to have zero gap in the split when finished so two oversize pieces are soldered or glued together and machined to final dimensions on all surfaces except the back side face this is left to finish to the final thickness determined by the turbine mechanic in the field. I can see the solder joint in the part but Dresser Rand, Ingersoll, and or Siemens are not forth coming with the recommended procedure for breaking that joint. Dresser would only tell the plant manager to send it back to them and they would split it for them meanwhile the turbine mechanic is sitting in his hotel at I dont know how much per day in cost to the customer. I can see different ways to do this but would always appreciate insight if someone else has done it before. I have another one scheduled in a couple of weeks for another plant that is the same part but bigger and I do not think it is soldered together. This is for a gas turbine it is 23" dia with a 16" hole but that will be whole different experience I am sure

RE: Split Bearing spacer

Thanks for the explaination
a Thrust Bearing shim was the only thing I could think of from first post info.


BUT, I have never encountered a TB Shim that had to have a 100% circle seperation joint. However this being a much smaller diameter than what I've seen so maybe it is desired ensure a snug radial fit.

(edit) Is this "shim" the race for a roller/ball?

The ones I worked require the shim joint to be positioned vertical to lap over the housing horizonal joint. both halves also had a notch at one joint to mate with an key pin in the top of the upper half housing

(I Only worked GE large steam turbines)

One thing related to machining that did cause a lot of errors I saw was the need for one surface to have the edges chamfered so that the radius of the housing fit would allow a "hard" face to face.

If I had the oppertunity, I would have both faces edges beveled so the shim could be installed either way

RE: Split Bearing spacer

(OP)
No it is not the bearing race it is the backup surface for a kingsbury type thrust bearing from my understanding (again I am just the machinist and not in contact with the whole machine just the parts they bring me.)

I am willing to guess that this solder joint is going to be a low temp solder meant to be split when finished I am thinking I can get it in an oven at 250 to 350 degrees lay it on a rod along the joint and it should separate when it hits the melting point.

That is what I will propose to the customer at least unless I find some better information in the mean time. Thanks for your interest in my little problem here.

RE: Split Bearing spacer

I'd worry about the solder melting method, because it will leave an irregular and non-reproducible gap. If the part is actually going to be a reaction surface for a Kingsbury bearing, your customer will want a relatively leakproof joint.

... which in turn suggests a lapped parting plane, with two alignment dowels and two tangential bolts, which is only possible because of the part's thickness.

... or cold-fracture the solder joint at a temperature that leaves the solder brittle.

Mike Halloran
Pembroke Pines, FL, USA

RE: Split Bearing spacer

Photo is NOT smptrsn bearing.

I found this pic to show about chamfering the edge so it will fit into the radius of the housing.
these two halves of the shim are not a precision joint.


Having a "soldered" joint sounds like it will cause a problem when grinding the shim. I would assume you will flip the shim several times to get it "flat" before making the grind for size. I seem to recall the mag of the grinder can pull a wavey shim flat and make a springy shim when installed

RE: Split Bearing spacer

(OP)
Actually the bearing side of the shim came finished from the factory, everything was finished but the final thickness and that all had to come off the back side of the disc to keep the factory finish on the working side.

I understand what is being said about the joint not being leak free but this is not my design I just am looking for a proper way to separate this factory provided part so it does not need to be sent back to the factory to be separated.

I will try to take a pic of the disc when I get back in the shop monday but the parting line is so faint now with a fine finish on both sides it is very hard to see was much easier to see before I finished the back side.

RE: Split Bearing spacer

(OP)
Just to close this out Factory finally got back to us with this reply

“After they have fit the rotor and trimmed the filler ring to their final dimension, they need to put it in a padded vise with the split parallel to the jaws and strike the top with a soft face hammer- place a hand behind top piece to catch it. They are only soldered together but sometimes it takes a good whack”

Thank you!

Best Regards,


Took 6 days for these words of wisdom, I did it in a much more controlled manor.

RE: Split Bearing spacer

Thanks for the follow up!

I had never seen such
I posted this question on a generator/turbine site (IGTC) and not a single reply.

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