Hey cold, you don’t scare me!
You know when you leave your car sitting outside in the cold in winter and, when you have to use it, you need to warm it up first? Well, now imagine the same effect on the various components of your project. Low temperatures modify the physical and mechanical-dynamic characteristics of the materials and can cause premature malfunctions of the mechanical devices housed within.
The design of a mechanical device must always take into consideration the lower limit of operating temperature to which the various components can go. In these cases, the lubricants have the task of guaranteeing operation up to such temperatures. But which lubricants? Oils or greases? In this post, we will focus on the appropriate use of low temperature greases.
Let's start by trying to understand why lubrication is important for low temperatures. The decay process caused by the inadequacy of the "cold" lubricating fluid is rather linear and characterised by a precise sequence of events:
The lubricant is thus the solution to seek out in order to manage low operating temperatures. But which lubricant is able to best meet these needs? Oil or grease?
In general, grease is preferred over oil in all fields of application characterised by an open housing to be lubricated – think valves, gearmotors or bearings. In all such components, a low-viscosity lubricant could leak out so a high adhesiveness is required to favor the position in the housing.
On the other hand, a high viscosity could be counterproductive at low temperatures, due to the greater friction that would be created. This is the case, for example, with cryogenic valves, gearmotors or bearings that operate in cold external environments or air-conditioned internal places.
How then can a lubricating grease be improved or optimized to be compatible with low temperature use?
The components that make up a lubricating fluid are essentially four:
Read more from our blog: Synthetic oil and mineral oil: 5 characteristics compared.