OPEN VS CLOSED BEARINGS: EXPERT INSIGHTS

Welcome to "Wiki Bearings," where we unravel the mysteries of bearings to help you make informed decisions. In this episode, hosted by Hassanein Alwan, we explore the intriguing world of open vs. closed bearings.

Open or closed? That is the question! Join us as we delve into the nuances of these two bearing types, examining their unique characteristics, applications, and advantages. You'll gain a deep understanding of when to choose open bearings and when closed bearings are the better option.

Whether you're a seasoned engineer or a curious enthusiast, this episode offers valuable insights to enhance your understanding of bearings. Tune in now and let Hassanein Alwan empower you with expert knowledge to optimize your bearing selection process.

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Transcript

[00:00:00] Welcome to Wiki bearings, where we dive into the worlds of engineering excellence, from the automotive marvels to the industrial giants. Join us to explore the wonders that keeps the world in motion. My name is Hassan Alwan, and I'm your host.

Welcome to another episode of Wiki bearings. In today's episode, we're going to talk about open versus closed type bearings. We're going to talk about the different types, when and why do we use them? And we're going to bust the myth around this topic. We know that there is a lot of bearings that are closed type, what we call them sealed or shielded, and then the open types.

And then many times people are confused. Do I use the closed type? Do I use the sealed one? The shield one? Which one is better? And so on. Now, when we think about [00:01:00] Close bearings and many times what comes to the mind are the ball bearings because they are the most common, the most versatile and the most common in sealed.

But of course, if there are spherical roller bearings, the latest generation, they can come in sealed types, needle rollers, uh, bearing units, most of them come sealed. So there, it's not only about ball bearings. I can understand that we think about ball bearings because we see them more often in in everyday application in our washing machine or it's a mixer or it's a vacuum cleaner.

So it's much more visible in our skateboards, roll blades and so on. So this makes them more visible and we think more about that. Now, we will not talk into all the different types of bearings that come sealed, but we will Dive deeper into the different types of seal and open types and what the difference and how when to use them.

When talking about sealed bearings, I [00:02:00] think before that we have to understand what is unsealed bearings now, or what we call them, the unsealed bearings. open type. So unsealed or open type bearings that are bearings that doesn't have a seal, it's fully exposed. We call them like the open book bearing. So you can see through them, you can see the components, the rolling elements.

name it. And usually they are very interesting when looking at them because you can see all the components rolling in there, but they at the same time have their own challenges. Now, now let's look at the brighter sides. Now, what is the benefit of having an open type bearings? Now, many engineers think about them, as the mechanical dreams, because everything is visible.

It's easy to lubricate, it's easy to see if there are any contamination, any issues, it's, it's even visually visible. So it's very, very easy [00:03:00] to inspect, change, re lubricate, do the maintenance. Now the other advantage to it is the looking at the temperature. Now, when it comes to seal bearings, usually because of the seal, we cannot go up to a higher operational temperature, but when it's an open bearings, the temperature is the higher operation temperature is not a problem.

So this is two things, the accessibility and the temperature when it comes to open bearing. Now, what are the drawbacks? What are the disadvantage of having Now, what I will call them, the contamination chaos. Now, you have an open bearing, you are welcoming all the contaminations, dust, dirt, moist, water, so everything around in that environment can lead to the bearing damaging in it, shortening its lifespan.

Now, the other disadvantage, these bearings loves lubrication. Because there is [00:04:00] nothing that prevents the lubrication from leaking out, so you have to keep relubricating, greasing, and so on. So, they could waste a lot of lubrication, compared to this. To a normal bearing or let's call it compared to a sealed bearing.

Now, at what environment or what, where, and when do we use open bearings? I think if we don't need, or there is not so many, so much of contamination indoor, clean environments where we need. more maintenance for other reasons, then it's easier to maintain and we can use an open bearings. Now you will find a lots of applications like could be households application.

Some of them indoor machineries is using open types. Now, I think when it comes to some, uh, sport equipment as well, where you use them indoor, I say a thread mill, uh, all of the sports equipment. Some [00:05:00] of them of course are sealed, but many of them are open because usually you don't have a very contaminated environment, uh, in a gym.

So I hope we now know and understand unsealed bearing. Now let's talk about the sealed bearing. Now, When we think about a seal bearing, most of the time we think about the rubber seal. But actually, we call shielded bearing or metal sealed bearings is another type that we can also talk about. Now, when we think about seal bearing, we think about RS, which is the most common suffix we use.

and comes from sealed bearings or rubber, actually it comes from rubber seal, so RS, and closed type is 2RS, uh, two side closed type is 2RS. So it's very simple as the word said, it's a bearing where we have put some walls to protect the bearing from external contamination. [00:06:00] Now, what are the, the advantages of, of a seal bear?

Of course, less contamination, less dirt, dust, wet, uh, less exposure to the environment, which means normally a longer span for the bearing. So a better life for a bear. Now, the other advantage is usually these bearings are lubricated for life. So you don't need to relubricate to do the maintenance or less maintenance, less hassle.

So simply you save time and you can save money. And if this is the right application equipment for the right environment. So, not everywhere, as we said, not every time, a sealed bearing is the right, but if it's the right application, we save time, money, and cost, as we don't need to re lubricate or do maintenance.

Now, the disadvantage of, of having a, a sealed bearing, one is, it's a high [00:07:00] friction factor. These bearings are, the seals are always in contact with the metal, and it's caused, now this friction is not very high. Thank you. But there is a friction. So if we need low torque bearings, we maybe should find another, another types of bearing.

We're going to talk about our sealed or shielded bearings. Uh, they can be also an option. Now there is a small friction happening and, uh, the seal can get damaged if we are using very high speed on a sealed bearing. So if we have high speeds. And the friction is, is, is a problem. Let's say because of the torque, then seal bearing is not the right choice.

Now, if we have a higher operating temperature, the seal can get damaged or degraded and over time, the ceiling is not anymore working. So you get all the dust and the lifetime, the lifespan of the bearing get damaged. When we talk about [00:08:00] rubber seal, we always think about contact seals. Now, what we call them RS, the two RS seals.

But there we have also other types of seals. There are many different types here, but in today's episode, we're going to cover the contacts and the non contact seals. Now, the general contact seals, which is the 2RS, the common type seal, are usually very good in sealing the bearing from wet, moist dust, and it is the best sealing out and protects the leak of the grease or the lubrication.

from the bearings. Now, the non contact on the other hand is, uh, what we call them the labyrinth seals. They work a little bit differently. They are non contact seals, and they are more, the shape of it is as a labyrinth, which trap the contamination outside. So it prevent it from entering. It's make it a bit tricky for the contamination or the [00:09:00] dust or the moist to enter the bearing at the same time, make it difficult.

For the lubrication to leak out of the bearing, but it is non contact, which means it's not the same protection as a fully sealed bearings. So we have the contact and non contact. Now, the advantage of non contact is when it comes to speed. So if we have higher speed and we still need a good sealing, then maybe a contact and non contact seal is the solution.

As there is less friction, maybe, yes, it's, there is a slight disadvantage on the ceiling, but that is very minimal, so non contact seals are a very good option for higher speed. Now, cost can be also a player here, or we maybe can look at it as a disadvantage, they are slightly higher in cost. non contact seals slightly higher in cost.

Not, not always the case, not all the sizes, not all the types, but there can be [00:10:00] a cost implication to it. Now for rubber seals in general, seal bearings, we can see them in many different applications. Automotive, it can be in wheel bearings. We can see them in electrical motors and agriculture. Now when you look at the, uh, the environment of the agriculture industry, harvesters, all this dust, mud, weight, rain, name it.

All the contamination are there. So. In most of these applications, we need sealed bearings. Now we have households application where I don't know, we have a mixer where there is wet environments, there is water and so on. We need sealed bearings. So it is now becoming, if we look at the industry, we are moving slowly to more sealed.

application to protect and to have less maintenance, maintenance, free bearings, greased for lives, and so on. So we are slowly moving to that direction. And also I think it's a good, we started to have [00:11:00] also a cleaner environment in most of the cases, but as we move, even in sometime in a clearing our environment, as we move to have or interested in less maintenance bearings, we are moving to sealed bearings.

When we talk about seals, I think it's worth mentioning the metal seal or the shielded bearings. Now, instead of a rubber seal, we use a metal. Now, this is not as good sealing and protection for the bearing as a rubber, but still a good protection, especially for other contaminations that not are not so fine contaminations.

So, Now, what is the advantage of, of having a, uh, a metal seal? One, it can take higher speed as there is no contact with the metal. So it takes much higher speed. And as metal is not impacted so much by temperature. So you don't get that degrading of the seal [00:12:00] throughout time or the, with temperature. So usually if we have speed, if we have a higher operational temperature, and most of the time we choose metal.

Shields or metal seals. Now, commonly we call them ZZ seals, ZZ shield. And usually we can see them compared to the seals. The rubber seals are black rubber. The other one, usually metal can come in silver, goldish color, depending on the brand and so on. Of course. Now, when we cover the, when we looked at both the metal shield, the seals and the non contact, the contact, then we are somehow confused.

So how do I know which one is which one different brand have it? So let's try to decode all the suffix around this. What does that [00:13:00] mean? Now open when you don't have a suffix. If you have 6202, there is no suffix. Usually it's an open type. If you have 2RS or you have ZZ, most of the time, this means this bearing is shield or sealed.

Now there are many brands outside and there are many. They have so many different suffix representing the sealed bearings. I'm going to talk about the top brands. So you just have, you get an idea. Now, if we look at SKF, SKF is using 2RS. The same thing is using Koyo. Uh, now NTN using LLU. NSK is using D-D-U-F-A-F-A-G using two HRS.

Now all what I said is related to normal contact rubber seal. Now there are other brands like uh, nci, which is two NSE and so on. So if we [00:14:00] have a bearing that says 6 3 0 5 2 Rs in. And SKF, which means it's a rubber seal. The same thing for Coyo. If said LLU 6305, LLU C3, most probably it's a seal bearing with a C3 clearance.

Now, most of the brand, when it comes to shield, most common brands are using either double Z. or 2Z. So ZZ or number 2NZ. Now, most of the common brands are using the same for all the metal shield. Now, when it comes to the non contact, the labyrinth seals is a little bit trickier because every brand come up with their own suffix.

Starting with SKF, they're using RZ or 2RZ if it's sealed both times. NTN using LLB, NSK is [00:15:00] using VV, FAG are using 2BRS. Koyo is using 2RU and then Nachi is using 2NKE. Now, of course I cannot mention all the brands. When it's come to, to non contact seals, actually not every brand Is having this types of seals.

Usually it's requires years of experience, knowledge in ceiling bearing, so you will have mainly the top brand are using the non contact seals. So it's not very common, but these are, as I, I named the most common brands and the most. So just to recap that, I know maybe I went too fast. So for SKF, they are using 2RZ.

NTN using LLB, NSKR using VV, NACHI is using 2NKE, or NKE for one side and 2 for two sides, then COYO with 2RU [00:16:00] and 2BRS for FAG. I know that you think, but I have seen other types of seals, or I've heard some Other suffixes, yes, there are special types, phyton seals, different types of seals, special application seals, I know in NTN there is LLH, um, and there are more high temperature seals and so on.

Now, this is not the time to discuss this, we can go deeper, but these are the most common sealed and shield bearer. As I said, we're gonna Bust the myth around this. So some of you have asked this question, the most common questions are the myths outside in the market. And so as we sell hundreds of thousands, millions of these bearings to different markets, there are some perception about one is good.

The other one is not so good. And so on. And we have seen in some markets that they buy [00:17:00] one type of seals and they don't buy the other one. They think this one is better. And so on. Now, I have four main myths that I would like to discuss with you and give you some, some, and we'll see if it's a myth or if it's true.

So the first one is seal bearing requires no maintenance. Is this a myth or is it true? I would say in most of the cases it's true for normal application. Now, if we exceed the speed of the bearing or the operational temperature, now, for whatever reason is that, then maybe we have to look at the bearing again and see if the seals are still intact.

Do we have a bleeding from the, from the seal for the lubrication? Do we see lubrication around the bearing? Something like this. We have to look at this just to check. If we, we see these signs, maybe we should [00:18:00] reseal the bearing or change the bearings. So that requires now in normal application, normal conditions, the bearing does not need any maintenance, almost no maintenance and it's grease for life.

So there is no problem. So I would say yes, seal bearing requires. minimal maintenance. I will not use the word no maintenance, but I will say minimal maintenance. Another topic that we see some, some people talks about, uh, that the sealed bearing lasts forever. This is obviously a myth. There is no bearing that lasts forever.

Yes, they can last very long. You can, you can have. Uh, bearings that you put in a certain application or you can have it in your household application and you never need to change it. They never need to do anything. You never need to look at it, but we cannot say that they last forever. Every bearing is designed for a certain lifespan.

Now this lifespan could be 10 years, could be 20 years, could be five years, but [00:19:00] there is a lifespan. So the bearing does never last forever. But if we have the right seal and the right application, they will last long enough that you don't need to worry about them or you don't need to change them. Like a simple example, uh, a wheel bearing a sealed wheel bearing last a hundred thousand kilometers, maybe 80 and in harsh road condition, maybe 120 and let's say more bumpy roads or muddy roads and so on.

But they last 400, 000 kilometers, give or take that also says that it's not lasting forever. So you have to change the bearing around a hundred, 120, 000 kilometers. Now, some hub bearings with advanced technology, advanced ceiling, much more protected. 000 kilometers, but again, they don't last forever. So seal bearing last forever.

Is a myth. [00:20:00] Now, another question or another, uh, that I heard always that sealed bearings are always quieter. Now this is maybe true depending on sometime open type sealed with oil. And when you have a higher speed, the noise can be higher than a seal bearing. Now with the grease inside a seal bearing, the noise can be less.

Yes, but you still, if it's a higher speed, you still, there is a contact with the seal. So not necessarily much lower. So I would, I would say it's not necessarily, but seal bearing are slightly quieter than an open type. So our final one sealed bearing are more expensive than open type. So there is a lot of concept about sealed bearings are more expensive and maybe open type, but.

Let's, let's look at in, in two different ways. [00:21:00] One, in some sizes. Of bearings, there are more production on sealed ones than open types because of the production size. Maybe a million, a batch of millions of bearings are produced sealed. The cost can be the same. Or sometimes even less now when it comes to so we cannot generalize.

Yes, as we are adding a seal as we are lubricating that there is logically a cost to this. When we go, if we produce smaller batches, open types, a thousand batch, it's actually more expensive to produce when compared to producing a million bearing sealed. So that is one aspect. The other aspect, if we look at the cost.

Relubricating, maintenance, the continuous inspection of the bearing, the open type to see if the condition can be [00:22:00] way more costly if you really need a sealed bearing. So when it comes to the cost, it's negligible cost compared to an open type that you need to do all the maintenance and relubrication and inspection all the time.

So here I would say it's not the most, it's more expensive. It will be for you. Way, way cheaper. I hope you, in this episode, we are able to cover the sealed and the open tab. You understand what is the difference between all of them. And we, I hope that I was able to enlighten you on all of this. Thank you for today and see you next time.

And that wraps another episode of Wiki bearings. Don't forget to subscribe for more insight into the fascinating realm of the engineering innovation. Until next time, keep spinning towards greatness.