silver solder need help

[tusk]

This is my first post and not much of an into.
I am an active member on Metal Meet.com and asked this question. That site is mostly all sheet metal content but a member directed me to this site.

I'm looking for help with a silver solder project.

Where I work we maching and finish grind wrist pins for a number of GM engines. They are ground to size on a thru feed grind line with cincinnati certerless grinders with grind wheels about 24" in dia. X 3' long.
The wrist pins pass thru a pair of grind wheels and grind it to size after 3 grinds, ruff, semi and finish. In each opperation there are 2 plates with carbide silver soldered to it 32" long that the wrist pins
spin on as they pass thru each grinder..
We currently silver solder carbide on in 6" sections . Engineering now wants them with a full peice of 32" carbide soldered to it. We don't know how to do this and NOT have warpage. Engineering wants
to job it out to a shop that does electro induction soldering which they claim has no warpage.
I'm not really sure the job shop does induction soldering,but I am sure that engineering does not want to have to come up with a solution.

The rest plates are 3/4" X 4" X 32" hot rolles 1020 steel with a milled edge at about 45 degrees the length (32") of the rest plate. This is where the carbide gets soldered to. Ribbion solder and past is placed
between the carbide and the rest plate, then heated with a torch and soldered. From there the carbide is ground to the disred angle and ground straight

I sugested that a fixture with clamping be made to hold the rest plate along with clamping the full 32" of carbide then using a rose bud torch or even 2 to get it up to temp quickly, but they tell me it won't
work.
Also the carbide size is about 3/16" X 1/2" X 32" and there is a lip machined on the milled angle for the carbide to rest against.
So I am looking for sugestions on how to do this
Remember we currently have not done more than 6" at a time. Any silver solder experts out there? I want to prove them wrong if I can.
Doug

[shovelon]

I would suggest Vacuam braze. The key point is slow heating and cooling.

There is a company Thermal Vac Technologies, in Orange, California. They do heat treating and brazing.

I have used them many times for submarine cavity antenna housings. Give them a call and see what they say.

http://www.thermal-vac.com/contact-us/

[Fred s]

I vote for some knid of furnace barzing operation as well, 32" is a bunch to get up to heat evenly. May be in for some warpage, could even pop the carbide strip. Is this the center work support you are putting the edge on?

[lotechman]

Induction heating done by professionals is very fast and the heat can be applied evenly according to the manner in which the coils are arranged. If someone is doing this in your area I think it would be the way to go.
I have used induction heating for pre and post heat welding. You can put the heat where you want it and ramp it up fast or slowly according to the situation and the amount of power available.
I am trying to imagine the cost of a piece of carbide 32 inches long and I think it would be staggering. carbide uses powder metallugy and a 32 inch long die would need an awful lot of pressure spread over that distance. After that the biscuit would be sintered.

[Oldiron2]

Induction heating done by professionals is very fast and the heat can be applied evenly according to the manner in which the coils are arranged. If someone is doing this in your area I think it would be the way to go.
I have used induction heating for pre and post heat welding. You can put the heat where you want it and ramp it up fast or slowly according to the situation and the amount of power available.
I am trying to imagine the cost of a piece of carbide 32 inches long and I think it would be staggering. carbide uses powder metallugy and a 32 inch long die would need an awful lot of pressure spread over that distance. After that the biscuit would be sintered.

You missed where the first post stated:

"Also the carbide size is about 3/16" X 1/2" X 32" and there is a lip machined on the milled angle for the carbide to rest against."

Having one long carbide piece with the different coefficient of expansion compared to steel would create a difficult problem when the brazing was done.

[lotechman]

No I just can't get my head around the idea of such a long thin piece of solid carbide. The stuff is not cast.

[Oldiron2]

No I just can't get my head around the idea of such a long thin piece of solid carbide. The stuff is not cast.

My mistake; I've been preoccupied lately and didn't look carefully enough to see it was that long, even when I quoted the sentence. I was thinking it was lots of smaller pieces, although I had wondered how that could perform the needed job. I do agree with you about making such a long, thin piece.

Sorry for the error.

[lotechman]

I would seriously like to know how the job is finally done.. I am wondering if a travelling ring of inductance coils would be best chasing the heat from one end to the other. The idea being to heat only a small location at once and travelling along. Maybe two coils starting at the center and travelling in opposite directions. It likely would take less than two minutes. An old text I have shows coils made from copper pipe squashed and bent to shape and water running through to keep it cool.

[tusk]

Well I don't know how much the sticks of carbide cost but we have half a dozen or so layin around here.
Job will probably go out and I think to a shop local. Ya'll got my intrest up now and I'll end up going to the shop after just ta find out how they do it.