Stainless Steel Tapered Roller Bearings

[MASSEY]

We use tons of tapered roller bearings, but our supplier does not manufacture stainless steel ones.

We can get stainless steel ball bearings - good quality, no problems.

I would like to try some stainless steel tapered roller bearings (SSTRBs). But I don't have time or money to waste on poor quality.

Do any of you currently use SSTRBs and if so, who makes them?

 

[MASSEY]

HIPPO41,

We stock and use SS ball bearings. I need SS TRBs because the BDR and Static load ratings are much higher for relative size as compared to BB.

The draw back with Cylindrical Roller Bearings is the abscence of thrust [axial] load handling capability.

Thanks for the input.

 

[MASSEY]

CovyUK,

I just got finished reading up on the new ICOS oil seal from SKF and CR. It might work well for your application. They are available in the 6000 series BB in sizes from 12mm to 40mm.
The concept takes a traditional Chicago Rawhide spring lip shaft oil seal and mounts it on the bearing unit directly.

 

[strokersix]

MASSEY,

Any chance you could combine a cylindrical roller and a ball thrust bearing to accomplish what you need to do?

Mike

 

[sancat]

Massey,
Is there any specific reason why you have to avoid sealings?
Is "use SSTRB" a designer's specification?

Since your application calls for a tappered roller bearing, your load is not so light. I would prefer to use a lip seal, with some kind of laberinth, and the whole roller cavity filled with grease that would escape/fill the laberinth when the roller is lubbed, taking out any grease that might have emulsified.

sancat

 

[MASSEY]

Strokersix, I don't think the incorporation a thrust bearing is practical for two reasons: first is space limitations and the second is cost. These brgs are used for a manufactured line of products of which we produce tens of thousands per year, we search for savings in fractions of pennies per product. Another problem with a thrust brg is how the load would be transferred to it. With the BBs and TRBs the axial component of thrust loading is applied through a retaining ring for the BBs and the cup spacer for TRBs.

Sancat, we use sealings now, fortunatly SSTRB is not a designer spec. You see, we offer standard products and stainless steel products. The SS products that use BB are all SS. But the SS products using TRBs are all SS except for the Brgs. I was just searching for SSTRBs so the entire product could be advertised and sold as SS. This would be an appealing selling point for food handling industries.

 

[abdul]

Massey,

Interesting replies from everyone....I like difficult problems like this, it takes the cobwebs off of my brain.

Here is one more solution: Use radial stainless steel ball bearings, in addition to a single stainless steel ball-thrust bearing, which is placed at the shaft shoulder, just outboard of the radial bearing (which is on the major diameter).

The ball thrust bearings are practical if your shaft surface velocities are not excessive. I don't know if you are familiar with these, they have the balls rotating on a race which is oriented axially with respect to the shaft.


One more solution: Maybe you can find Silicon Nitride bearings in tapered roller bearing format, running in a stainless steel race. There are also other types of ceramic rolling element bearings, but prices may become prohibitive. However, I have seen a lot of purchasers fork over a lot of money just to satisfy a small detail in the purchase specification.

Naturally, the ceramic roller bearings are just as corrosion resistant as stainless steels. They are normally used in high temperature applications.

Abdul

 

[Russian1]

what is the applicaton where SS would be necessary. If it is say saltwater corrosion, then you need to use a duplex stainless steel for starters, not just any stainless. Second, have you looked into coatings for the bearings, such as Xylan, ceramkote, or even plating. I see by your earlier statements that cost is a factor so I would guess that Inconel, Monel, Hastoloy or something like that is our of the question

 

[MASSEY]

abdul, the SS BBs have sufficient thrust capacity relative to radial capacity. So combining a dedicated thrust brg with standard single row deep grooves seems unecessary. The problem comes with higher radial load ratings where TRBs are required. Their thrust capacity is also relative and sufficient. The other suggestions would also 'work' but are not appealing due to cost.

Russian1, you hit the important point in that the TRBs are not "necessary" which is good in that they are not available. The reason I was trying to locate them as stated above in various places is that when customers request a SS product it would be 'nice' to provide them with a SS product - not a product that has SS components with non-SS brgs.

Typical requests are in sterilzers, wash-down environments, food processing lines, or corrosive environments. We do use coatings on the TRBs we put in SS products. This seems to be the only solution available at the time.

I'm perplexed that SSTRBs are not available, especially since SSBBs are available.

I appreciate everyones' comments and input.

 

[abdul]

Massey,

If the shaft rpm does not exceed 500 rpm, then why not use graphite sleeve bearings, with captured grease lubrication, such as using O-rings rubbing lightly on the shaft.

 

[testy]

Have you looked into angular contact ball bearings such as those used in spindle bearings? These can take an appreciable amount of side load while maintaining the advantages of ball bearings.

 

[diamondjim]

Stainless steels are difficult to get the
required surface hardnesses and the capactities
fall off quickly. I do see straight stainless
steel rollers being incorporated in wire race
designs. If they can make stainless steel
rollers, I assume the tapered races could be
made if the quantities were sufficient. The wires
that they roll on are about 51Rc and hardened
and passivated. I am not certain about the hardness
of the rollers but I would guess about 55Rc.
AFBMA lists stainless steel as a material suitable
for rollers. I do not know the hardening technique
required to harden the races of a tapered raceway.
The cup should be easy but the cone would be very
difficult. I do not know if stainless steel requires
any special grease to be incorporated into the design to be compatable with the application.