According to Oleksandr Gutnichenko and Lanny Kirkhorn at Lund University in Sweden, the challenge is to make the new lubricants more efficient than the old ones. And the key additive is sawdust!

All sheet metal components, such as those in a car, are produced from thin metal sheets that are cut to size, lubricated, placed in a mould and pressed to obtain the right shape. After pressing, all the parts are sticky from the lubricant and must be cleaned before they are painted. The sticky lubricant is used to reduce friction when surfaces come into contact during movement in the processing of metal parts, and to cool down the process. In the past, the black lubricating oil got everywhere in workshops; on machines, in the air, on hands…

“I have seen machines that were sprayed with 50 litres of an oil-water mix per minute – lubricant that also contained a variety of hazardous additives”, says Oleksandr Gutnichenko of the Division of Industrial Production. Spraying large volumes of such an oil into cutting machines or press moulds is hazardous to health and can lead to asthma, allergies and skin problems.

We start with a wood product such as sawdust.

Nowadays, the oil is not so conspicuous in engineering works throughout industry, but fluid lubrication ­– often mineral oil (from fossil oil) mixed with water – is still used. Furthermore, the lubricants still contain a range of more or less hazardous additives, which are there to improve lubrication and cooling.

“The strategy over the past 20 years has been to reduce the amount of oil by means such as installing MQL (Minimum Quantity Lubrication) systems. We have also seen the start of a trend to replace hazardous mineral oils with vegetable oils, such as rapeseed oil”, says Lanny Kirkhorn, a colleague of Oleksandr Gutnichenko, adding

“If we replace today’s methods with MQL and rapeseed oil-based lubricants, we have already made good progress by eliminating many hazardous components. However, one of the problems at present is that many industries do not want to change their methods and invest in new technology because they have a well-established lubrication process that works, even though there are negative effects.”

Oleksandr Gutnichenko are Lanny Kirkhorn are now trying to make the rapeseed oil lubricant more efficient than current hazardous lubricants by developing harmless additives that can improve lubrication performance, which will further reduce energy consumption and wear on machine tools.

The researchers use a renewable waste product such as sawdust to enhance the rapeseed oil as a lubricant and thus make it easier for the engineering industry to switch from mineral oils to vegetable oils for lubrication.

They have now developed a nano-graphite powder, which can be added to the rapeseed when mixed with water.

“Graphite”, explains Oleksandr Gutnichenko, “is a type of carbon with a crystalline structure made up of nano-thin layers. These soft flakes get in between the two surfaces of the different materials and act as a lubricant, for example in connection with forging or mould pressing of sheet metal.”

In their tests, the graphite additive has been shown to reduce friction by up to 25 per cent. It will now be tested in industrial production, but Oleksandr Gutnichenko already knows that it will not work in all types of production.

“Even though the graphite flakes are nano-thin, they are too broad to get into the cutting zones in metal-cutting operations. This requires even smaller particles.”

As it is difficult and energy-intensive to break up graphite into even smaller pieces, Oleksandr Gutnichenko has come up with another solution that involves sawdust.

“We start with a wood product such as sawdust. Firstly, the sawdust is heated to remove water, oils and other unwanted substances. Then we continue to heat the sawdust in a number of processes until finally we have tiny graphite crystals as well as amorphous carbon (carbon particles with weak structures). We can then peel off the graphite in nano-thin flakes and also destroy the weak amorphous carbon material so that it forms nano-carbon particles that are even smaller than the nano-graphite.”

This method uses a renewable waste product such as sawdust to enhance the rapeseed oil as a lubricant and thus make it easier for the engineering industry to switch from mineral oils to vegetable oils for lubrication.