question : overlay build up on cast iron

Can you machine it down in the seal area then either shrink or weld a steel (or other material) tire to it? You'd have to post-machine, of course, but you had to do that anyway.

I might give that a try but I think I am going to have to overlay it

I would seriously investigate welding with aluminum bronze welding wire using a wire feed welder. You are going to need some sort of rolls or axle drive unit and a source of heat for post and preheat. A hundred pound tank of propane and a weed burner should do the trick. If you have some sort of power rolls you likely could clamp your gun in position and just monitor buildup as it sits above the rotating piston. The reason I suggest aluminum bronze is its ease of machining and the ability to put a superior material on using a semiautomatic process. If you build up with nickel alloy I am sure the cost would be comparable and if you developed a hard spot you would not like to be near the machinist when he discovers it. The alloy has been used to build up bearing slide surfaces on cast iron and the amount of admixture with the iron is minimal. You don't need as much preheat. My guess is around 300 F. should be more than plenty. I am sure that if you made an enquiry the supplier should have some suggestions on the use of this alloy. It is going to cost a bundle for the wire. You might ask if it is wise to machine the area to ensure a proper bond and remove trace oil.. I know Ernie has used this wire. I have only seen it demonstrated and ran a short bead. The stuff went on like butter. Randy

Try Belzona Super-metal.

It is an epoxy overlay used for build up of large shafts and cylinders. Amazing stuff. Not cheap, but really good.

If this sparks like steel, there's at least a possibility that it is a cast steel. If it's cast iron you might have some trouble with the oil in it, but if it's steel it'll be a gravy job.

Generally, if you can torch cut a ferrous alloy with a torch it'll weld nicely with most rod (except, IIRC, manganese steel, but I'd be surprised to see manganese steel inside a hydraulic cylinder..). Nick 'er with a torch and see how it goes, you gotta build it up anyway.. that's how I'd approach it.

John

well we welded up the first one today , used 12 pounds 99 nickel wire

the 35 lb roll was 900.00

did a little machining to see about hard spots, machined really nice , I went ahead and undercut a full eighth of an inch to minimize hardening at my weld surface

I had night shift put the " toaster " a modified oven resistance burner , under the piston and set it on med low as the shaft spun overnight in the big lathe we do this work in , this morning it was a nice three hundred twenty degrees , proceeded to weld it up after a good cleaning with acetone and a little more pre heat , after welding two strips half inch wide all the way around the whole casting only raised up to 525 its cooling now , will finish machine tomorrow

would like a specific vendor for the aluminum bronze though