Cooling lubricants are used in metal machining processes in order to cool the contact zone between tool and work piece, to lubricate and flush away the chips produced. So far, they are based to a large extent on petroleum, the annual consumption in Germany amounts to about 80,000 t. The use of these lubricants is detrimental - because of issues regarding the health and environmental impact and the emergence of mineral oil wastes. To overcome these disadvantages, a lubricant was developed on the basis of glycerin and water. Involved were the Institute for Ecological and Green Chemistry Braunschweig, the Institute for Machine Tools and Production Engineering of the Technical University of Braunschweig, the lubricant manufacturer DAW AEROCIT Lubrication GmbH (Zwickau / Saxony) and the Carl Bechem GmbH (Hagen).
Within the biodiesel production, glycerin occurs in large quantities as a by-product. At current, globally at least 300,000 tons of excess glycerin is burned for energy production. In terms of a cascading use the glycerin is to be used prior to its energy recovery as new coolant. Field tests showed a better performance of the glycerin-based coolant in comparison to commercially available mineral oil products. Through the use of glycerol also a bio-stabilizing effect was achieved, therefore the conventional biocidal additives are redundant. Compared with conventional lubricants, the glycerin-based coolant as a sustainable product has environmental advantages and is technically and economically competitive.
