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New Developments in Biobased Metalworking and Other Lubricants

April 01, 2013
Lou Honary
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Biobased products are maturing and are better received in many applications than in the years past. This is due to the continuous improvement in their quality and an inherent high lubricity that shines when used in metalworking applications. Biobased lubricants are produced from modified vegetable oils, biobased derived synthetic esters, and a combination of those mixed with a number of performance enhancing additives. Industrial lubricants as opposed to automotive lubricants include way oils, hydraulic fluids, greases and metal cutting oils and water emulsified coolants. Biobased versions of these products are now commonly used either exclusively or side by side with the conventional oils in many shops.

Vegetable oils in general offer superb lubricity, and due to their lower volatility and higher thin film strength they can be a great source of base oils for metalworking applications. These oils help to improve tool life and reduce fire hazards. Vegetable oils, however, would need to be chemically modified and fortified with various anti-oxidants to survive the demanding environment of metalworking machinery. Chemical modifications of vegetable oils which could be as simple as hydrogenation to more complex esterification processes can add to the cost of the final product.  Products that are not oxidatively stable lead to rancidity and odor in cutting oils and to breakdown in coolants.

Due to the notoriety of biofuels and the need for non-food base oils for use in biofuels, there is an increased interest in industrial crops. In addition to known industrial oils such as castor and linseed, there are other oils like jojoba, camelina, cuphea and lesquerella, to name a few, that are less known but are among oils being investigated for their industrial use potential. A review of the research at the Association for Advancement of Industrial Crops (AAIC) shows the breadth of the new crops being investigated for industrial applications. Biobased lubricants have been the beneficiary of the increased interest and investment in the biofuel technologies.

Simultaneously, there have been advances in the crop seed technologies, especially in soybean seeds that yield soybeans with healthier oils. Such oils generally do not require hydrogenation, which is used to improve oxidation stability in frying. Hydrogenation tends to result in the formation of trans-fats and negative health consequences. The non-food use of these new, healthier oils is promising because the infrastructure for creating large volumes is already in place. Once these seeds enter the agriculture markets with some premium for growing, the farming industry can deliver large volumes in effectively.

Major brands of these soybean oils are known for their higher oleic acid content. These oils present a high level of oxidation stability for frying and perform well in lubricant applications where high stability is desired. The high stability oils can have dual use having been designed for more stability in frying but perform well on industrial uses. There are also new oils from unconventional sources such as algae. High oleic and stable oils from algae are commercially available with potential for use in industrial and metalworking applications.

The current trend is for enhanced vegetable oils from modified seeds or algae with high stability to be used for improved biobased metalworking fluids and other industrial lubricants and greases. Gradually, a shift to non-food industrial crops, especially those that are native to various geographic locations and can be processed regionally will increase the use of biobased products. Some of these products will be made with vegetable oils are not modified but include performance enhancing additives. Other products, especially when designed for large scale use, will be bio oils that are chemically modified mostly through esterification so as to remove any variability in performance due to changes in the growing season. Simple and complex esters can be manufactured from many biobased oils including vegetable oil and animal fats and yield a tight tolerance in performance. This could then mimic the performance of petroleum oils that are classified in groups I, II, etc.

Lou Honary is Professor and Director at the UNI-National Ag-Based Lubricants Center.

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