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Hardfacing/machining bearing race for cam follower

DanielG

Stainless
Joined
Oct 22, 2014
Location
Maine
I'm looking at running some large 3" OD cam followers on a ~50" diameter steel ring made of A36 or A572. Given the loads and duty cycle, this will probably be okay, but if I'm looking at a harder option. Getting hard steel that large is going to be very expensive, so I'm wondering about hardfacing the race, then turning it on a VTL. I know they do weld repairs like this on camshafts and the like, but not much about it. What might be a good hardfacing alloy that is wear resistant and machinable?
 
Hard facing and machinable don't belong in the same sentence :D However, that never stopped me from doing it anyways. I always used Greenleaf WG300 ceramics to knock the humps off. Pretty amazing ceramic, you'd swear when using it that what you're cutting maybe isn't all that hard, then you stroke it with an old file, which skates off it :D

I used a tool steel welding rod, which is not as hard as the super alloy hard faces, but still hard. Pretty expensive rod, and wow, a 50" ring sounds like a helluva chore to face all over. Might take hundreds of dollars worth of rods.

There is no such thing as a moderately hard deposit: it goes on very hard, and then maybe you can temper it back a bit if you have a furnace to do it with.

How heavy is this ring going to be? It is going to warp horribly if welded only on one side, so you might have to weld both sides to keep it decently flat.

How about getting a ring cut from AR plate: abrasion resistant plate. It comes in various flavors, I think AR450 (brinell 450) is pretty decently hard, and can be used as is, or machined with carbide, and drilled slowly with HSS.
 
I think you are overthinking this project. What are you worried about with the a36 not working? Maybe adding a few more cam followers to spread the load.
I have done quite a bit of hard facing and i sure wouldn't go that route.
 
How about a burnout or rolled ring of 4140 and have it heat treated?
By "rolling" I am referring to a hot forging process.
 
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Thanks for all of the input. Based on the feedback, it doesn't look like this is a good option. That's the reason I ask these questions on PM, you get good answers.
 
Now you've all got me wondering how they do this for camshaft repairs. Is it the fact that they're grinding it back to shape, so the lack of machinability doesn't matter as much?
 
Now you've all got me wondering how they do this for camshaft repairs. Is it the fact that they're grinding it back to shape, so the lack of machinability doesn't matter as much?

I would have to imagine so, yes. Plus they'd probably be using a welding positioner to get a very smooth and uniform deposit and the heat input would also be very uniform and self cancelling to far as distortion is concerned. The camshaft is solid so it doesn't get wavy from welding like a ring would.

Long hard face welds also have a cracking problem,.

Have you considered rolling a ring? What cross section are you dealing with here? I assume the roller is on the outside of the ring?
 
I mentioned it in the other thread, get it cut in hardox, your pick from 45HRC on up into the 60HRC range, the 45-50HRC is not to bad to just machine with std carbide lathe tooling, but is a bitch to drill!
 
Now you've all got me wondering how they do this for camshaft repairs. Is it the fact that they're grinding it back to shape, so the lack of machinability doesn't matter as much?
For roller cams they do not do hardfacing. That's for sliding followers. On an automotive roller cam the case is roughly .050" deep and you need every thou of it. Reputable places won't do regrinds on roller cams and they don't hard-face them, either. New core required.
 








 
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