In winter, have you taken measures to protect your equipment from the cold?
author: Leila
2024-10-09
Winter is an important season for the maintenance of various machines, equipment and cars. As cold air strikes again and again, the temperature is getting lower and lower. Many people know that high temperature is not good for equipment, which will damage equipment components, accelerate oil deterioration and even bring fire hazards, but many people ignore the harm of low temperature to equipment.
We may have heard that in winter, equipment or vehicles are difficult or impossible to start. The normal operation of equipment requires good lubrication. When the equipment is running, metal parts rub against each other. If there is no lubrication, the equipment parts will be damaged by dry friction, and high temperature will be generated due to severe friction, causing parts to burn. Therefore, lubrication is a necessary condition for the normal operation and protection of equipment. Low temperature will cause the lubricating oil to flow poorly or even stop flowing, and cannot reach the lubrication part, causing cold start difficulties or even start failures. If the equipment is running under poor lubrication, it will also cause dry friction and damage parts.
1. The impact of low temperature on lubricating oil:
The impact of low temperature on lubricating oil is mainly viscosity and additives. Low temperature will increase the viscosity of lubricating oil, reduce fluidity, and even cause different oil layers in more extreme cases. Low temperature will also affect the solubility of additives. From the composition of lubricating oil, some additives are dissolved in the base oil. Low temperature will cause the additives to precipitate and weaken the performance of the lubricating oil.
Low temperature will increase the viscosity of lubricating oil and reduce its fluidity. Just like edible oil, it becomes thinner at high temperature and thicker at low temperature, and its fluidity becomes worse.
When the temperature drops to a certain level, it will stop flowing. The temperature at which lubricating oil just stops flowing at low temperature is the pour point. Therefore, below the pour point, the lubricating oil stops flowing. When the temperature approaches the pour point, the viscosity of the oil will increase significantly, the fluidity and circulation of the oil will deteriorate, and the machine is prone to lack of oil.
Low temperature will affect many lubrication systems. For the circulating oil supply system, due to the increase in the viscosity of the lubricating oil, the oil flow will be blocked, and the insufficient oil flow will make it difficult to start or insufficient oil supply. Splash lubrication will also be affected. For example, in a gearbox with splash lubrication, the gear is lubricated by the lubricating oil soaked on the tooth surface during rotation. Due to the increase in the viscosity of the lubricating oil at low temperature, not only will the torque of the gear rotation increase, increasing energy consumption, but also some parts will be poorly lubricated. When the gears rotate, they transfer the lubricating oil to other gear teeth to provide them with lubrication. If the fluidity of the oil is not good, it will cause insufficient transmission of the lubricating oil.
2. How low a temperature should we pay attention to?
How low a temperature is prone to problems? Generally speaking, there is no problem with the use of current lubricating oils and greases at 0℃. At -10℃, the overall performance of many lubricating oils and greases will not be significantly affected. But if the temperature is as low as -20℃, the situation is different. Some lubricating oils are close to or have reached the pour point. To be on the safe side, we recommend that the minimum operating temperature of the lubricating oil be at least 10℃ higher than the pour point.
The low-temperature performance of lubricating oil is mainly affected by the base oil, and some other additives such as pour point depressants can also help reduce the pour point of the lubricating oil.
Ordinary lubricating oils use mineral oil as the base oil. When the temperature is as low as -20℃, the fluidity of the mineral oil has been significantly reduced and the flow is not smooth. If the equipment will encounter temperatures of -20℃ or even lower during use, then the impact of low temperature on the lubricating oil must be considered. PAO (or SHC) is a synthetic oil with excellent low temperature performance. Even without the use of pour point depressants, PAO can adapt to low temperatures below -20℃, and some PAOs can even have a pour point as low as -50℃.
The reason why PAO has excellent low temperature performance is that it does not contain paraffin, will not wax at low temperatures, and the oil flows smoothly. On the other hand, it is because of its high viscosity index.
The viscosity of lubricating oil is affected by temperature: when the temperature rises, the viscosity of the lubricating oil decreases (becomes thinner); when the temperature drops, the viscosity of the lubricating oil increases (becomes thicker) and may even not flow normally, just like cooking oil. Viscosity index (VI: Viscosity Index) is referred to as viscosity index. The higher the viscosity index of the lubricating oil, the more stable the viscosity of the lubricating oil (the better the viscosity-temperature performance) under temperature changes, that is, the smaller the viscosity change. The high viscosity index of PAO enables it to adapt to a larger temperature range. Compared with mineral oil, PAO has better performance at high and low temperatures.
3. Indicators reflecting the low temperature performance of lubricating oil:
The pour point of lubricating oil is the main indicator of low temperature performance. Some equipment also requires us to pay attention to low temperature viscosity. For grease, it is low temperature torque and flow pressure. ASTM is a common international lubricant quality standard.
For low temperature problems, users should choose suitable lubricants based on reasonable selection. In addition to choosing oils with excellent low temperature performance, there are other solutions to solve low temperature problems, such as using heaters, thickening, avoiding oil line bends, etc., which help oil flow smoothly.
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