Nitronic 60 sleeve and bushing
Nitronic 60 sleeve and bushing
(OP)
I am trying to select a sleeve and bushing material. Operation is a bottom auger for a large chemical vat processing paint pigment, 50% solids and water, somewhat abrasive. There is a large universal joint at the bottom that drives the auger. The cross of the joint has pressed on replaceable sleeves, the yokes of the joint have stationary bushings. 304SS is the auger and vessel material and it has held up well. The old sleeve and bushings were carbon steel 4140 Rc50. They have to run dry except for the water to avoid contamination. The 4140 would corrode badly. I am looking to go to Nitronic 60 for both the sleeve and bushing. Little concerned because the rockwell is only 20 on the Nitronic 60 and it can't be heat hardened. Loading is mild by the auger, the cross rocks about 15 degrees in the yoke, as the auger spins at 30 rpm.
Should I be concerned that both the sleeve and the bushing will be have low hardness.
PS, I am not a materials engineer but a mechanical engineer.
Should I be concerned that both the sleeve and the bushing will be have low hardness.
PS, I am not a materials engineer but a mechanical engineer.





RE: Nitronic 60 sleeve and bushing
I would suggest SS like 420 or 440B/C hardened near 50Rc.
RE: Nitronic 60 sleeve and bushing
http://www.stellite.com/
RE: Nitronic 60 sleeve and bushing
Researching all the stainlesses, they all have very low galling thresholds, even 17-4 when hardened to 42Rc. One person suggested I try 17-4 annealed and machined to fit at Rc28 on one piece, say the bushing, and 17-4 H950 at Rc42. He claimed that the 12 point difference in hardness would prevent galling. But I can't find any literature to support that.
The other option is to stay with steel, like 8620, carburized to Rc60, then ground. While this may be a better bearing surface, the corrosion would probably be the same.
Is there any ideas out there to help me. Coatings are just to expensive and time consuming. Often the bushings have to be in a couple day for emergency repairs, and while close they are not all identical. I need a material that can be handled and the local machine shop, preferably without heat treating and grinding. Carbon or SS is acceptable.
Here's the link
http://www.hpalloy.com/DataSheets/ni60.htm
just below the title click, see full brochure.
thanks again to all you experts.
RE: Nitronic 60 sleeve and bushing
http://www
http://www
Click on Technical Data Bluesheet for both of these links
http://ww
http://www.cartech.com/
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
Galling will always be problem if both are same material and operating poor lubrication. People who say to keep hardness very different to prevent galling are having different experience than I, we always get galling problem no matter what.
Other idea is what you say to 8620, carbonitride or such and secondary finish. We found for corrosion: get good core hardness (~Rc30), finish operation (we like hard turn in this range), then gas nitride (do not machine white layer after this), corrosion resistance and wear is very good, even better than 440. Problem for us was the distortion from last nitride. Maybe this work for you?
Is sleeve or bushing more problem? Do one in stainless and other in 8620 like written, solve galling and give trial for both materials...
RE: Nitronic 60 sleeve and bushing
With the austenitic stainless grades that show some wear and gaulling resistance, the reson is that they surface work harden a lot in service. When we cold draw tubing in those grades we can get over 150ksi UTS and mid 30's Rc without any trouble.
= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Nitronic 60 sleeve and bushing
The stainless idea would definately solve the corrision problem. Using the 8620 and carburizing, finish cutting, and then nitriding it getting to expensive. Plus trying both doesn't prove that when self mated it would work (for the 440C). This is not a high load condition, I may get away with the SS not galling if I pick the right combination. 440C and Nitronic 60 show no galling to 50 ksi, but I am skeptical of the softness of the nitronic 60.
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
www.gocarlson.com/AlloyPDF/Nitronic60.pdf
RE: Nitronic 60 sleeve and bushing
(just a brainstorm thought, D7 chemistry says 11.5%-13.5%Wt-Cr -- almost stainless)
RE: Nitronic 60 sleeve and bushing
The Cr is all tied up in carbide form. Not stainless at all.
RE: Nitronic 60 sleeve and bushing
440C, 416, Nitronic 60.
440 and 416 have a higher resistance to gall than 440c self mated. 416 and 316 is even higher. But the 316 may be too soft. If I went with 316 I could as easily go with the N60.
Slow rpms, moderate load, abrasive, run dry, simple and reasonably priced.
If I can't feel reasonably comfortable on a decision I have to revert back to 4140, and that was not really the best choice.
RE: Nitronic 60 sleeve and bushing
haze10 Why not consider attaching a zinc anode so that it is in electrical contact with the universal joint?
That should alleviate galvanic corrosion which is probably occurring between the submerged part of the 304 auger and the 4140 universal joint, and at least let you select mechanically durable bushings and pins.
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
The easiest is N60 versus N60, straight machining, no grinding, no plating.
Next is N60 bushings versus 440C Rc60 sleeves. I have to heat treat and grind the sleeve, but the bushing is still just lathe turned, no plating.
Next is 440C Rc62 sleeve, versus 416 Rc53 bushing with 2/10" flash chrome. both pieces have to be machined, heat treated, ground, and the bushings chromed.
Next is 4140 or 8620 through hardened to Rc55, machined, heat treated, ground, flash chromed.
As you can see the N60 v N60 would be the simplest and cheapest way to go, but there is no telling how the relatively soft N60 would hold up to the grit, and to the physical loading. But I do believe the loading is relatively light as there is not great resistance in turning the auger in the slurry.
Help!
RE: Nitronic 60 sleeve and bushing
For to address galling issue, try 8620 turned bushing and gas nitride (do not machine white layer), corrosion resistance can be better than 440 and wear is very good as surface hardness Rc70. Do sleeve as 440C turned and then heat treated to Rc55. Geometric distortion of both 8620 and 440C should be less than 0.03mm from heat treat is this problem?
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
ht
RE: Nitronic 60 sleeve and bushing
I plan to document the construction and installation of the parts, and how well they perform in the application. I will report back to everyone.
Thanks for all your help to date.
RE: Nitronic 60 sleeve and bushing
We ran a pilot plant with a conical mixer with a knuckle at the bottom that caused the arms to rotate. It was quite similar to the one at the GS URL below. As received, this knuckle suffered extreme wear until the moving components were coated with Tribaloy (800). Extremely expensive but very effective. The abrasive media was TiO2.
Mixer
http:
Tribaloy
http://www.stellite.com/wear_corrosion_alloys.asp
RE: Nitronic 60 sleeve and bushing
If it were me, I would use 440C vs Nit 50 or 60. Though the duplex 2205 actully works well as a bearing.
Any CS, it doesn't matter how it is surface treated, will corrode.
= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
If you are using 440C for both, don't worry about the hardness. Just don't use tehm at their peak harness, Rc 50 should be plenty, and double temper. You want some toughness, it prevent microcracking.
= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Nitronic 60 sleeve and bushing
Based on my experience 440C at 50 Rc will not offer very good abrasive wear resistence. We have knives made from 440C cutting a very abrasive polymer and the higher the hardness, > 58 Rc, the better the wear resistence by several orders of magnitude. There is not need for a hardness difference.
Again based on my experience and limited literature on 440C the galling threshold is fairly low in a self-mated couple. This may or may not be consideration as any liquid will act as a lubricant and greatly improve the galling and wear even though it may contain the abrasive.
You might want to look at 440XH SS from Carpenter. This alloy is capable of higher hardness while maintaining the corrosion resistance of 440C. What little experience I’ve had with this alloy it was looking very good in some of our applications on both the wear and galling aspects.
RE: Nitronic 60 sleeve and bushing
So now I am going to run two tests, one with Toughmet self mated, and the other with N60 self mated. When buying N60 shop around, for a 3.5" x24" round bar I was getting prices from $450 to $1100, with HP Alloy being the lowest. The N60 like the Toughmet will require only machining, no heat treating, no grinding, no plating. If it works it will be a big advantage.
RE: Nitronic 60 sleeve and bushing
Another place to try is Baldwin International. They supply specialty steels specifically for abrasive wear applications and have a good knowledge of various applications and propoerties relating to hardness, work hardeneing and machinability
I have some contact info for one of thier reps if interested.
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
htt
h
http:
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing
RE: Nitronic 60 sleeve and bushing