Biodegradable lubricants for bearings applications

This development has been possible thanks to the work of SKF with their own suppliers in identifying the characteristics and performance requirements most appropriate to get a green fat. The application of biodegradable greases and lubricants has been studied in the center of engineering and research of SKF for several years. This has led to the award of a formula capable of complying with the strict demands of a wide range of applications for the engineering without adverse effects on the environment.

While only a small part of lubricants used represents a danger to the environment they represent millions of tons throughout the world. Specifically, users of construction equipment, the work of explanación, forestry and agricultural industry seek more and more ecological solutions that environmental pollution is a problem.

Until recently, it was thought that the current generations of biodegradable lubricants and of low toxicity would not be able to successfully meet the requirements of the applications of rolling bearing.

SKF has managed to overcome the disadvantages associated with biodegradable greases which caused premature wear of bearings. LGGB 2 has been tested and approved for smooth steel with steel bearings and roller and ball bearings. The fat is made from synthetic ester oil, lithium/calcium thickeners and other biodegradable, being a low toxicity fat ingredients.

• the existing and proposed legislation in the field of environment in regard to lubricants,
• products existing on the market and its performance,
• the demand for the product,
• the properties of the product and
• the current research.

The main issue was to establish a clear definition of the term "ecological lubricant". Most of the materials are degraded in one way or another over time. These changes are caused by different processes, almost always biodegradation, oxidation and photolysis. The physical and chemical alterations produced with the passage of time often occur simultaneously.

As for the development of clear parameters on the decomposition of materials in the context of organic fat, it is essential to understand what is the biodegradation. In the biodegradation material decomposes gradually as a result of the metabolic action of organisms such as bacteria, fungi, yeast and algae. Through this process the hydrocarbons that are the main component of biodegradable lubricants are transformed into carbon dioxide and water.

Naturally, this process is not completely predictable since it can be influenced by the mix of these living organisms, the temperature and humidity. It can happen to a material that can degrade easily under a series of circumstances do not under others.

The minimum basic requirements are a sufficient population of bacteria, correct levels of oxygen and an appropriate temperature range. The rate of degradation is also affected by the viscosity of the fluid, sunlight, the content of mineral salts, the availability of nitrogen, pH levels, solubility and the ability of bacteria to adapt to the oily nutrient source. Finally, lubricant should be reduced to its simplest natural without that generate dangerous derivatives that could harm the environment in the long run.

Conventional lubricants based on mineral and synthetic oils are ultimately biodegradable while its slow decomposition process involves, in some circumstances, which may subsist as contaminants in groundwater nearly a century.

Without that there is no universal rule which clearly define the term biodegradability, SKF chose to use a series of existing tests. These tests were used to establish whether the toxicity and biodegradability took place within a reasonable period of time.

Fundamentally, the biodegradation means that the microorganisms in the soil, rivers and oceans can break down fats with relative ease.

From in-depth studies, SKF has learned that carefully formulated in the lubricating fluids plants or ester behave well in real applications. In particular, SKF researchers have found that the combination of oil synthetic ester with a lithium/calcium thickener has been good in what refers to the water and the corrosion resistance without its being necessary to use toxic additives.

The formula of grease LGGB 2, based on these components, shows good performance with smooth, ball and roller bearing. It's a significant step forward because normally the conventional biodegradable lubricants only considered appropriate for a particular type of bearing. Each bearing type has different interaction that can affect the performance of the lubricant. For example, the film of lubricant in bearings of ball has a point contact; in roller bearings a contact line; and in total contact with the surface smooth bearings. SKF has selected four different formulas that have been subjected to more stringent testing of bearing. Such as:

• the SKF R0F test to determine the bearings of ball and the maximum working temperature limit performance,
• the SKF EMCOR test, which test the properties of inhibition corrosion,
• test R2F to establish performance of grease lubrication of roller bearings and
• plain bearings SKF test steel with steel.

From these tests, it was found that LGGB 2 offered superior performance in a series of working conditions and bearing types and provided a uniform working temperature set at 90 ° C.