Many companies produce a silicone grease including us. These greases have many advantages - a wide range of working temperature, inertness to rubber and plastic, absence of smell and color, safety. It would seem that these greases can be described as the most multipurpose product –apply wherever you want, furthermore silicone grease has no difference in touch between silicone and classic greases – both of them are lubricous.
However, the main wrong belief lies in this! Grease properties cannot be determined, except the color, without special equipment, though this equipment would shows the difference in greases bases. Let's perform an experiment on our beloved four-ball wear machine.
1. Standardized four-ball wear test machine
2. Let's take 2 bases: silicone oil (left), mineral oil (right)
3. We put balls in the cup, 3 of them are down and 1 is up
4. And we put in top holder. Pressure is made through the lever. Cup presses with 3 balls from the bottom to the top one.
5. We fill the cup with silicone oil to the edges.
6. Installing to the machine. We transfer the sample carefully, hanging weights.
7. The experiment itself. We calculate the load via this table.
10 seconds, the load is 60 kg
8. The results with silicone oil. Wear is seen with unaided eye.
Wear is 2.3mm under microscope
9. We repeat experiment with mineral oil.
We fill mineral oil. Waiting for bubbles to come out.
Installing in wear machine
10. The results with mineral oil. Contact patch is 0.8mm in 10 seconds and 60kg load.
It is clearly seen that the contact patch is bigger in times after the first experiment. This is a consequence of poor bearing capacity of the silicone oil film. And all silicone greases based on silicone oils. In simple words, the silicone oil film is breaking under less load than greases based on mineral oil can withstand. All of these confirm that silicone greases can work in unloaded plastic and rubber units and more rarely in metal nodes. As for the rest, the silicone grease is ideal for everyday life and also as protection against external influences. Creaking door? Suitable! Seized glove compartment? Suitable! Flowing tap? Also suitable. But you should choose non-silicone grease for bearings, hypoid gearing, normal gears, etc. Otherwise you will get the following results:
Balls were overheated and welded together.