The term bio-lubricants is becoming much more commonplace in the market, and significant growth is forecast for bio-based lubricants over the coming years. So what are bio-lubricants, and what are the main differences between them and your more traditional products?
One of the key reasons we are seeing more bio-based products is the growing focus of companies to improve their environmental awareness and impact. In addition, changes in legislation and the fact that petroleum based products will eventually run out, have also led to a need to develop and improve other technology.
Bio-based lubricants are derived from vegetable, plant or animal based materials. While they usually display greater lubricity than mineral oils and have a high viscosity index, they have limited temperature capabilities, inferior oxidation stability and a limited shelf life. They are also not compatible with mineral oils, so it’s important to remember that if you are switching from a mineral to a bio-based lubricant, the system will need to be purged first.
The advantages of bio-based lubricants:
- High viscosity index, meaning less change to the structure of the oil at different temperatures
- High flash point, which could be over 300 degrees celcius compared to around 200 degrees for most mineral oils
- Biodegradable (unless the non-biodegradable additive content is exceptionally high)
- Less toxic
- Renewable
The disadvantages of bio-based lubricants:
- Poor oxidation stability – they can be chemically modified or additives inserted to improve oxidation
- High pour point affecting performance in cold conditions – often a mineral oil or biodegradable synthetic ester is added to improve performance
- High cost – products tend to be more expensive and there is the additional cost of system downtime during product switch
It’s worth mentioning that if you are looking for environmentally friendly lubricants, there are other options to bio-based products. Under the ISO 6747-4 standard for biodegradable hydraulic fluids coming into contact with water, there are three main classifications: triglycerides (vegetable oils), synthetic esters and polyglycols. Synthetic esters outperform triglycerides in most areas, specifically working better at extremes of temperature, and with low volatility. Polyglycols have many of the same benefits as synthetic esters, but don’t react with water as readily and are nearly non-toxic. Polyglycols are not compatible with hydrocarbon-based fluids however, so are not miscible with mineral oils.