When it comes to oils/greases in many instances the decision is made to go with 1 middle of the road choice.
Does your environment effect your lubrication choice?
We make dozens of decisions every day, some simple, some more complex. Some internet sources estimate that an adult makes about 35,000 conscious decisions each day. We make 226.7 decisions each day on just food alone.
In a world of growing choices and options how do we decide on the best lubrication option for our machinery to keep our assets in optimal condition and keep the wheels turning?
When it comes to oils/greases in many instances the decision is made to go with 1 middle of the road choice
- VG220 for gearboxes
- EP2 grease for bearings
- VG46 for hydraulics
The aim to make lubrication choice quick, easy, and cheap. In some cases, the decision is made to use 1 specific lubricant universally as it “worked well in 1 application so must be good quality”.
As many seasoned engineers will know not all lubricants are created equally. A more effective way than the previous method would be to look at OEM specifications for lubricants and choose the supply of lubricant that is listed in the manual of the machinery. This gives some assurance that the grade has been tested to the “operating standard” and will give adequate protection for your assets and keep your plant moving. This is also a big factor in the decision process when it comes to machine warranty.
But is this enough when it comes to choosing your machine lubrication?
In many cases a machine design can be used for a wide variety of applications and are not specifically used for 1 environment, Take for example a chain drive. The same chain can be used on a piece of kit in a dry dusty brick works that could also be used on machinery destined for a food production environment which encounters wet environments. The chain is designed to use a lubricating CLP oil and will have an OEM recommendation listed in the user manual. In many cases though the brick works will choose to not lubricate the chain as the “wet oil” can accelerate the wear of the component. In this case the OEM recommendation is not fit for purpose in this application.
In another example heavy plant equipment will have an OEM lubrication list when the machine is delivered, But where is that plant equipment operating? The same piece of kit can be operational in hotter countries with increased temperatures as well as colder climates with temperatures falling into the minus. Would this have an effect on the lubrication choice of these 2 pieces of identical kit?
In a recent application the customer was operating in a cold store environment, They had a number of drive gearboxes within the cold store operating at -25 Degrees C. The customer had adhered to the “OEM specification” for the gearboxes of a mineral oil with a VG220 grade yet they still experienced high numbers of failures within the operation. The OEM recommendations had been followed and all warranties were covered on any equipment failure but there was still the issue of lost production and revenue due to the unplanned downtime.
What had not been taken into account was the effect of temperature on the lubricant when operating in such cold conditions. New oils are tested universally in line with International Standards Organization Viscosity Grade, ISO VG for short. Base oils are tested at 40 Degrees C when given there VG rating as a standard across the board. In the case of large changes to the operating temperature +\- the VG of the oil can change dramatically becoming thicker in cold environments and thinner in hotter environments.
These changes can have a detrimental effect of the lubricating properties of the oil in the machinery causing excessive drag in cold temperatures or loss of shear stability in higher temperatures. In the case of the cold store operating at -25 Degrees C the VG220 oil had become closer to a VG1000 resulting in high drag and loss of fluidity within the gearbox. This added strain led to higher rates of failures of the gearboxes resulting in increased downtime and loss of production.
Other factors can also occur with low temperatures which can affect the performance of the lubricant, some examples are listed below:
- lubricants can chemically degrade, separate into phases and exhibit altered physical states.
- Blended base oils can begin to separate into phases.
- Paraffinic base stocks can become waxy and form gels.
- Certain additives can become insoluble, resulting in settling, flocculation and formation of deposits.
- Dissolved water can transition to emulsified water (more harmful) and the settling of free water becomes impeded.
- Many additives that depend on heat-induced chemical reactions fail to perform (certain EP and AW additives, for instance).
- Oil can become too viscous to circulate.
Oil which becomes too high in temperature can also result in chemical changes which in turn can cause failures.
In 1903, Svante Arrhenius won a Nobel Prize when he figured out the relationship between temperature and most chemical reaction rates. Often called the Arrhenius Rate Rule, it relates to the fact that lubricants, once they've exceeded their base activation temperature, will degrade (oxidize) twice as fast for every 10°C increase in temperature. An oil designed to last 12 months at 40 Degrees C will reduce to 6 months when operation at 50 Degrees C, 3 months at 60 Degrees C etc.
In fact, there are a range of problems associated with too much heat, These can include:
- Accelerates additive and base oil decomposition.
- Some additives will volatilize and escape into the atmosphere.
- VI improvers shear down more rapidly.
- Microbial contaminants prefer warmer temperatures (but not scalding).
- Heat collapses oil films, causing accelerated abrasion and scuffing conditions.
- Hot oil shortens the life of filters and seals and accelerates corrosion.
- Oil more prone to leaking.
It is important to take these factors into account when choosing which lubricant, you use in your machines and is something you should discuss with your lubrication partner. Using a lubrication “partner” with the relevant knowledge can help with these decisions and can pay dividends in the long-term success of your machine Reliability and future productivity.
We recently held a webinar titled an introduction to lubrication, it went great and we hope you enjoyed it if you joined us. If you missed it or would like to watch it again you can do so by clicking here the password to view the recording is: 9u$+$v3u