Haris: Hello Martin, how are you?

Martin: Hello Haris, how are you doing?

Haris: Excellent! So, it’s a new Monday, new ice cream session… are you ready to eat your ice cream?

Martin: Absolutely, do you want some?

Haris: Virtual?

Martin: Well, I’ll tell you what, would you prefer a 00 ice cream or a number 2 ice cream?

Haris: Well, actually… number 2.

Martin: Number 2? you going to the stiff one, are you? You want it straight from the freezer.

Haris:  Exactly!

Martin: Look at that. Let’s talk about number 2 then, and of course many of you might have seen tubes of grease around the oil store with the number 2 in them and then, wondered perhaps maybe what that meant, and, of course, all products generally have certain letters that give some explanation about what we’re looking at.

So, LC for example might be a lithium complex thickener. Number 2 refers to the stiffness and what we have there is a number 2 grease which as you can see, as I hold the cup, nothing is happening. That grease is relatively stiff and is keeping its shape and it’s not moving.

But had you chosen the 00 grease, Haris, I would have warned you about spilling it on your shirt. Because what would happen with the 00 grease is, of course, that is a lot more fluid like. In fact, the 00 grease and the 000 grease are what is, essentially, a semi-fluid product and the actual numbers come from, what we say, the NLGI = the National Lubricating Grease Institute which is a body that is devoted to the cooperation of and a manufacturing of grease and it’s been around since the 1930s.

I recommend you take a look at their website to find out more information, but what we do have from the NLGI is a way to categorise the stiffness of the grease, because, apart from the viscosity of the oil itself, that we have to consider when we are looking at a grease, we have to look at the stiffness and, of course, we forgot two sorts of extremes here:

  • a 00 semi-fluid which is moving like a fluid and this one is actually a product built for things like steering racks on passenger vehicles and it’s ideal because as a semi-fluid as that rack moves and the gears and the teeth on the rack are moving that semi-fluid grease is lubricating all those gears nice and evenly.
  • Whereas the number 2 is better suited to something like a rolling element bearing where we want the thickener to be pushed to the outside to allow the oil to bleed in and lubricate the bearing but to keep the thickener to the outside so it kind of creates a groove in the grease and this is why we don’t want to overpack the bearing with grease because if you put too much grease in there the thickener gets in the way of the bearing and the other elements that are rotating and that causes drag and drag is heat and that’s why you’re bearing temperatures will increase accordingly.

So, we want something that’s stiffer in a rolling element bearing so it stays out of the way but lets the oil in and, hence, it’s a lovely simple demonstration but it’s a great way to see the difference between them.

Haris:  Exactly, I absolutely agree! This is what we fight very often against in trying to explain: how does the ball rolling element in a bearing feels when he needs to fight through all these greases which is in the way and creates a drag and creates a lot of additional friction which is completely unnecessary. But what we see very often in industry is one size fits all and that’s ok, let’s make it simple, let’s make a purchase department decide what we need, let’s get a good price and discount on the quantity and will find a grease that will fit absolutely all and that’s called as universal solution but that’s never a solution.

So, I’m very glad we discussed this because that’s something that really needs to be addressed.

Martin: Yeah, we commonly hear about the one-size-fits-all for grease. Nobody talks about one-size-fits-all for oil.

So, why would we talk about a one-size-fits-all for grease, especially as there are other issues as well such as things like the coupling greases that need to have an oil that has a similar specific gravity to the thickener, so that as that coupling is rotating at speed, we don’t get the oil separating out from the thickener.

So, yeah, valid point there.

Haris:  Yes, we hear it very often, it’s a good remark, why everybody is so careful about the oil and nobody cares about grease. While actually it’s the vice versa, the grease is a very complex issue, because it’s minimum three elements so a lot of things can go wrong, but unfortunately, still there is this idea of one-size-fits-all, is changing nicely and slowly and we will arrive to some nice situation soon.

Martin: Well, I’m glad about one thing that management haven’t decided that there is an ice cream that one-size-fits-all. I’m glad there are still different flavours.

Haris: Exactly! Now, when I was born, back in 1960s, and in this part of the world you had one or two maybe three ice creams, at least our ex-President liked to say so…

But at that time, you wouldn’t have chosen your vanilla Magnum with white chocolate!

Martin: No, so we are spoiled for choices now, aren’t we?

Haris: Ok Martin, thank you very much for this meeting.

Martin: Thank you for brightening up my Monday afternoon

Haris: Thank you for virtual ice cream and hope to see you next Monday.

Martin: Great, take care!

Bearing Lubrication Monitoring
Lubexpert