ZZ vs. 2RS Bearings: Which One to Choose for Motors?

If you’ve ever ordered deep groove ball bearings for electric motors, you’ve probably stared at the product list and wondered: should I go with ZZ or 2RS? It looks like a small detail. But get it wrong, and you might end up with noisy motors, failed seals, or bearings that overheat. 

Over the years at Welink Bearing, we’ve helped quite a few customers walk through this decision. So let me share what we’ve learned, straight from our grinding lines and assembly workshops.

First, what’s the real difference?

• ZZ bearings come with metal shields(usually steel) on both sides. They’re non-contact seals, meaning they don’t rub against the inner ring.

• 2RS bearings have contact rubber seals on both sides. The rubber lip touches the inner ring to create a tighter barrier.

Both keep dirt out and grease in. But they do it very differently.

And how this plays out in electric motors?

Electric motors have their own personality: high speeds, temperature changes, and sometimes dusty or humid environments. Here’s how ZZ and 2RS behave in real motor applications.

ZZ bearings, the speed-friendly workhorse. 

Because the metal shield doesn’t touch the inner ring, friction is extremely low. That means, higher speed capability, less heat generation and clean, simple design. Where we see ZZ bearings shine: motors that run clean and dry, think small fans, air conditioners, or precision instruments. If your motor operates in a relatively clean environment and speed is the priority, ZZ is often the smarter pick. But there’s a catch: metal shields don’t seal as tightly against moisture or fine dust. In a dirty or damp workshop, they can let contaminants sneak in over time.

2RS bearings, the protector.

Rubber seals(usually nitrile or similar) provide a much tighter seal. They keep out water, dust, and even small particles. However, because the seal contacts the inner ring, there’s extra friction. What that means for motors: better protection in harsh environments, slightly higher torque (the motor has to overcome seal drag) and lower maximum speed compared to ZZ. Good fit for washing machine motors, outdoor pumps, or any motor that lives near moisture or dust. Also a solid choice for RO booster pumps or drying machine motors, applications we often supply at Welink Bearing.

When someone calls us about motor bearings, we don’t jump to a quick answer. Instead, we ask:

① What’s the motor’s operating speed?

Above 10,000 rpm? ZZ usually wins. Moderate speeds? 2RS can work fine.

② Where will the motor run, clean factory or dusty job site?

Clean and dry, ZZ. Dusty, humid, or outdoor, 2RS.

③ Is noise a top concern?

Both can be quiet, but a damaged rubber seal or improper installation can create noise. At Welink Bearing, we run fully automatic noise testing on our bearings, so we catch those issues before they leave the factory.

④ Do you need maintenance-free operation?

2RS seals generally retain grease longer, especially in tougher conditions. ZZ bearings might lose grease faster if contamination gets past the shield.

There is a real example from our production lines. We produce deep groove ball bearings for all kinds of motors, from 604 to 6205 for household appliances, and 6200-6210 or 6305-6310 for larger electric motors. 

One of our customers builds compact motors for handheld tools. They started with 2RS because they wanted maximum protection. But at high speeds, the motors ran hot and lost efficiency. We switched them to ZZ with a high-quality grease, and problem solved. Lower heat, same protection in their clean assembly environment.

Another customer makes motors for agricultural fans. Dusty environment. They tried ZZ, but bearings failed early. Switched to 2RS, and life doubled.

There’s no absolute winner. It’s about matching the bearing to the motor’s real life.

What we do at Welink Bearing to get it right? We don’t guess. Every bearing we make, whether ZZ or 2RS, goes through the same strict checks:

■ 100% in-line clearance inspection, because wrong clearance kills motors faster than wrong seals.

■ Fully automatic greasing and capping machine, consistent grease fill, no under or over greasing.

■ Fully-automatic noise tester, we listen to every bearing so you don’t have to.

■ Dust-free assembly workshop, contamination is not welcome here.

And if you need something special, like a different seal material, a custom grease, or P5 and P4 precision, just ask and contact us at sales@welinkbearing.com. OEM and ODM is part of our daily work.