Angular Contact Bearing 2RS vs ZZ: What the Seal Does to Noise

For double row angular contact ball bearings, the choice between 2RS (contact rubber seals) and ZZ (pressed steel shields) is not the usual "sealed keeps dirt out, shielded runs faster" trade-off. On a double row bearing, each option shifts the noise risk onto a different manufacturing step — seal lip drag on one side, shield press-fit distortion on the other. This article explains what each one actually costs, using measured shop data.

The short answer

The honest summary: on a double row angular contact bearing, neither option is quieter by itself. What differs is which manufacturing step decides your noise result — and therefore what you should be asking a supplier to control.

Why the deep-groove answer doesn't transfer

Search "2RS vs ZZ" and nearly every article explains it with a 6205 deep groove ball bearing. A deep groove bearing has one ball row, one groove pair, a contact angle near zero, and decades of published test data behind it.

A double row angular contact bearing — a 5200/5300 series, or the 3200-type designs we build — is a different object:

• Two rows, behaving like a pair of single-row angular contact bearings mounted face to face, at a contact angle around 25°.
• The controlling internal dimension is not radial clearance but axial clearance, set by matching outer groove diameter, inner groove diameter and the distance between the two groove centres.
• The bearing is wider, so a closure disc sits further from the shoulder it is pressed into, and the ring has more length along which to distort.

So the generic conclusions — "2RS is slower", "ZZ is cheaper" — are drawn from a bearing whose failure modes are not yours. The useful question for a double row bearing is narrower: what does the seal choice do to axial clearance, running torque, and the vibration reading at final inspection?

What 2RS actually costs you — seal drag

A contact seal works because the lip presses on the inner ring. That pressure is also a friction source, acting on a bearing whose internal geometry is already sensitive to preload.

From one of our own measured sample batches — 5203-2RS, measured 2026-06-18. Sample data from that batch, not a specification:

The two grooves matched well — 2.7 µm apart on radius — and the finished bearings still scattered 6 dB. That gap is the point of this article. When groove geometry is good and the finished reading still moves, the remaining suspects are, in the order our shop works through them:

1. Raceway roundness and waviness — measured, not assumed
2. Superfinishing quality and raceway roughness
3. Cleanliness — residue, grinding sludge and swarf after washing
4. Seal lip friction and lip-edge burrs
5. Grease quantity, and where in the bearing it was injected
6. The axial clearance grouping of that individual unit

Items 4 and 5 exist only because the bearing is sealed. A 2RS unit gives you contamination protection and hands you two extra noise variables in exchange. Both are controllable — but only if someone is actually controlling them.

What ZZ actually costs you — the pressing operation

A steel shield adds no running friction. Its risk is concentrated into a single operation at the very end of the process, after all the grinding value is already in the part.

From our own double-row shielded assembly SOP, the shield-pressing step carries two hard rules:

• The press tooling must bear on the strongest edge of the shield, never on the centre of the disc. A dished shield touches the balls or the cage.
• After pressing, an operator turns the inner ring by hand. A continuous "sandy" rubbing sound means the shield has gone in too deep and is touching the cage. That unit is isolated, not shipped.

The same SOP maps noise by frequency band — worth borrowing for your own incoming inspection:

Note where the shield appears: low band (distortion) and high band (flaking). If a shielded double row bearing arrives noisy at low frequency, arguing about steel grade wastes everyone's time — ask how the shield was pressed.

The noise grade nobody can quote you

This is the part most comparison articles get wrong by omission.

In China, bearing vibration classes — Z, Z1, Z2, Z3, Z4, plus the ZP3/ZP4 peak limits — come from JB/T 7047-2006. Those limit tables cover deep groove ball bearings, bore 3–60 mm, in the 0, 2 and 3 diameter series. The structure is well known: for a given bore, each step from Z toward Z4 tightens the allowed acceleration level, and the limits rise with bore size.

There is no equivalent Z-class limit table for double row angular contact ball bearings.

So when a supplier tells you a 5203-2RS is "Z4", ask what it was measured against. Usually one of three things is happening: they are applying the deep-groove table for the same bore as an internal reference; they are quoting an Anderon-based in-house limit; or they are reporting a decibel reading from their own test rig — like the 32–38 dB figures above, which are our measured values on our equipment and are not a class.

None of those is dishonest. All three are unverifiable unless the measurement condition is written down. For a double row bearing, agree these four things in the RFQ:

• Which quantity — acceleration level (Z-style), Anderon by band, or dB on a stated instrument
• The test condition — applied load, speed, mounting, lubricated or dry
• Sampling — 100%, first and last piece per shift, or an AQL sample
• Where the limit came from — a national standard clause, your drawing, or the supplier's internal control

A supplier who can answer those four is controlling noise. A supplier who answers "Z4, no problem" is quoting a class that, for this bearing type, has no published table behind it.

For how the Z-grade system works on deep groove bearings, including the dB limit tables by bore size, see our separate guide: Bearing Noise Grades Z1–Z4.

A specification checklist for your RFQ

Copy this into your enquiry and you will get a far more useful quotation:

1. Seal type and the reason for it — contamination level, washdown, temperature range, whether running torque matters
2. Axial clearance window, not radial — state the range, and whether it is verified before or after the closure is fitted
3. Noise or vibration requirement — quantity, condition, sampling, and its source (see above)
4. Grease — type, and fill as a percentage of free internal space
5. Inspection evidence you want back — raceway roundness, groove radius, groove centre distance, axial clearance readings
6. What happens to a failed unit — stripped and re-matched, or scrapped

Point 5 separates suppliers. Any factory can promise a number; fewer can hand you the measurement it came from.

How we control it on the floor

For our double row work, both configurations run the same chain and diverge only at closure:

• Axial clearance is measured on 100% of units after ball loading and before the closure goes on, under a defined load, turning the inner ring two to three turns so the balls seat in the groove bottoms. Units outside the internal window go back for re-matching rather than forward to assembly.
• Grease is dosed by weight, injected into the gap between the two ball rows rather than smeared on the surface, with the dosing machine weight-checked at shift start.
• Raceways are measured after grinding; an out-of-range reading means the machine is adjusted and the raceway re-ground before the ring moves on.
• On 2RS work, the seal lip and its edge condition are treated as noise variables and checked whenever finished readings scatter.
• On ZZ work, the press tooling contact face and the hand-turn check after pressing are fixed inspection points.

If you are choosing between 2RS and ZZ for a non-standard double row bearing — or you have a drawing and are not sure which closure your application justifies — send us the outline dimensions with the application conditions: speed, load direction, temperature, environment, and whether running torque is critical. We review feasibility and propose a sample plan against your drawing.

FAQ

Is 2RS or ZZ quieter on a double row angular contact bearing?
Neither is inherently quieter. 2RS adds seal lip friction as a noise variable; ZZ concentrates the risk into the shield-pressing operation, which can distort the outer ring. What decides the result is which one the supplier controls.

Does the seal choice change the bearing's internal clearance?
The seal itself does not set clearance — axial clearance comes from groove diameters, groove centre distance and ball selection. But fitting the closure can distort the rings, which is why clearance should be verified before the closure goes on.

What does 2RS cost in running torque?
A contact lip rides on the inner ring and adds drag you can feel by hand. If your mechanism is torque-sensitive, say so in the enquiry rather than choosing the seal on contamination alone.

Can I ask for a Z4 double row angular contact bearing?
You can ask, but JB/T 7047-2006 vibration class tables cover deep groove ball bearings, not double row angular contact. Agree the measured quantity, test condition and sampling instead of relying on a class name.

Which one for a washdown or dusty environment?
2RS. Contact seals are the right answer where contamination is the dominant failure mode — accept the torque penalty and specify the noise requirement explicitly.

Can you supply a double row bearing to my drawing with a specific seal?
Yes — send outline dimensions and application conditions; sample development starts from a feasibility review.

Related resources

• Bearing Noise Grades Z1–Z4: dB Limits and What Buyers Should Specify
• Full-Complement Double Row Angular Contact Bearings: How We Developed the DW6
• Bearing Clearance C2, CN, C3, C4 Explained
• Axial Clearance on Double Row Angular Contact Bearings