What is the best high temperature grease?
In my work, the most frequently asked question may be "How much degree is this high-temperature grease?" When confronted with this question, I can only answer "The actual application is the best way to prove the quality of high-temperature grease, and It also depends on the length of the refueling cycle. It depends on how you choose." Sometimes customers will say: "Others are cheap and beautiful in color, we must choose cheap ones." So the problem is: high-temperature grease is cheap. it is good? Or should the color look good? Or is the special temperature resistance written on the packaging the better?
First look at the operating temperature of a few very good high-temperature greases (the following data comes from the manufacturer’s instructions) DuPont GPL226, the price is about two thousand yuan per kilo, the operating temperature is 30 ℃ to 260 ℃, Klüber FOMBLIN AR555, the price is about 1,000 yuan per kg, operating temperature-30 ℃-265 ℃ Kluber 74-401, the price is a few hundred or thousands of yuan per kilogram, operating temperature-30 ℃-220 ℃ Great Wall 7017-1, the price is a few hundred yuan, the operating temperature is -60 ℃-250 ℃. However, if you search the Internet for a large amount of ultra-high temperature grease, the price is not expensive, and the grease of tens of dollars can withstand temperature.
So where is the problem?
The dropping point is related to the use temperature. In fact, very often the temperature resistance refers to the temperature of the dropping point. Although the dropping point is a very important indicator to measure the high-temperature performance of grease, it is by no means the only indicator. Many lubricating grease merchants have taken advantage of the user’s point of view that high dropping point means high temperature resistance. In the product introduction, the dropping point is often marked on the outside, but the temperature that can be achieved may not even be high. Many greases have a dropping point of more than 300 degrees, or even no dropping point. For example, bentonite grease is not expensive. The temperature resistance of the grease is very high without a dropping point, but the disadvantage is also obvious. That is the grease. The degree of volatilization is also relatively fast. If it is mineral oil, the base oil will oxidize more quickly, the grease will become carbon deposits and agglomerates in a short time, and the base oil will evaporate or be oxidized. To determine the maximum use temperature of a grease, in addition to its dropping point, it also depends on its consistency at high temperatures, and the antioxidant capacity of the base oil and thickener. Parameters such as colloidal stability at high temperature. Therefore, grease with a high dropping point is good at high temperature resistance. Of course, high-temperature grease with a very low dropping point is generally not very good.
Second: Does a grease with a higher limit temperature have better performance?
For example, let’s say there are two types of grease:
The first type of grease can be used for one month at 210 degrees, but if it is used in an environment of 250 degrees, it will flow in a mess; it can only be called a temperature-resistant grease.
The second type of grease can be used for one week at 210 degrees, and it can be used for several hours or one day at 250 degrees. It can be called a better high temperature grease.
If your ambient temperature is very high, which one would you choose? Most importantly, we also need to consider the comprehensive performance of the grease. Mechanical stability-to avoid the grease becoming thinned out after high-speed rotation, extreme pressure resistance-better lubrication performance, can be used for heavy-duty bearings, thermal stability-to avoid grease heating Oil outflow · Oxidation stability-to avoid rapid oxidative failure of the grease at high temperature, water resistance-effective lubrication and better lubrication performance can be guaranteed even in the presence of water vapor-can be used for heavy-duty bearings.
Below I will take the case of using grease on a corrugator as an example. To prove that choosing the right grease is the best high temperature grease.
For high-temperature grease for corrugating machines in the cardboard industry, we also distinguish between new and old machines.
1. For bearings with poor sealing and high operating temperature, if the following phenomena currently exist: grease loss, the cause of piles of waste oil under the bearing may be:
(1) When the oil is just added, the excess grease is squeezed out
(2) Grease becomes soft at high temperature and flows out from the oil seal.
(3) Grease directly becomes liquid and flows out.
(4) The grease becomes ten in a short period of time, resulting in a large amount of carbon deposits,
1. Improve the anti-shear ability of the grease-reduce the tendency of the grease to become soft at high temperature, reduce the loss of the grease, and keep as much oil as possible in the bearing cavity.
2. Reduce oil volatilization loss. Extend the service life of the grease in the bearing, and it will not dry out in a longer period, so that the old oil can be discharged during the next regreasing, so as to ensure that no carbon deposits are generated in the bearing.
For relatively new or well-sealed machines, especially some high-speed machines, the focus of our consideration is that because the machine is well sealed, and in order to protect the swill seal, each time you do not add too much oil, so as not to cause excessive pressure and damage Oil seal, so the old grease cannot be effectively eliminated, so it is necessary to minimize the residue after the swill volatilization. For this reason, the special requirements for the lubricating grease are:
Excellent anti-oxidation ability of grease-extend grease life as long as possible and reduce the amount of lubrication. The cleanliness of the grease, the less residue after volatilization, the better.
Obviously, the so-called higher temperature resistance is not the best choice. Without the best high-temperature grease, it can only be a suitable product for suitable working conditions! The above is just the understanding of high temperature grease from the perspective of practical application, welcome your guidance!