What are the properties of lubricating oil

cold.knowledge - Basics of lubricating oils

In our first post we wrote about the basics of lubrication technology, friction and wear and the different types of lubricants. Now let's get you started on the basics of lubricating oils. This article is intended to give you an overview of what lubricating oils are, how they are structured and composed, what types of oil there are and what advantages and disadvantages they have.

What is a lubricating oil?

Lubricating oils are liquid media that, depending on the friction conditions in the friction point, serve as an intermediate and mostly as a construction element. They are one of the most important lubricants and are an essential component in the manufacture of lubricating greases.

“Oils” are liquid organic compounds that have to meet different quality requirements depending on the type of use. Depending on the application, it must be checked which requirements a lubricant must meet.

  1. Reduction of friction
  2. Reduction of wear and tear
  3. Reduction of energy losses
  4. Increase in oil service life with synthetic oils
  5. Approved by food law
  6. Rapidly biodegradable
  7. Corrosion protection
  8. Heat transfer medium
  9. Coolant or heat dissipation medium
  10. Lower maintenance costs

How is a lubricating oil composed?

Depending on the purpose and area of ​​application, the formulation of a lubricating oil consists of the following components:

What is viscosity?

Viscosity is a measure of the viscosity of a fluid. The viscosity is also referred to as the internal friction of the fluid. The higher the viscosity, the thicker (less flowable) the fluid (e.g. honey) is. The lower the viscosity, the thinner (more fluid) it is, i.e. it can flow faster under the same conditions (e.g. water). In the case of oils, the viscosity changes depending on the temperature. At low temperatures oils become thicker, at higher temperatures they become thinner. Motor oils and motor vehicle gear oils are divided into SAE classes, industrial oils into ISO viscosity grades (ISO VG).

Which ISO viscosity grades (ISO VG) are there?

According to DIN 51519 there are 18 different viscosity classes. The viscosity class is always set at a temperature of 40 ° C (V40).

Statements about practice

  1. Low viscosity lubricating oils (ISO VG 2 - 100):

They are used as penetrating oils, rust removers, hydraulic oils, compressor and vacuum pump oils or low-temperature oils for components such as chains, bearings and gears.

  1. Medium viscosity lubricating oils (ISO VG 150 - 460):

They are used as gear and chain oils in industry.

  1. Highly viscous lubricating oils (ISO VG 680 - 1500):

Are used as adhesive oils for slowly running open drives and gears or for chain lubrication.

What are the most common base oils in the industry?

  1. Mineral oil (paraffinic, naphthenic and aromatic) (MIN)
  2. Polyalphaolefins (PAO)
  3. Ester oils (E)
  4. Polyalkylene glycols (PAG)
  5. Silicone oils
  6. Perfluoropolyether oils (PFPE)

What is a mineral oil?

Mineral oil is obtained from the crude oil through distillation and refining. It consists of hydrocarbon compounds. Depending on the molecular composition, we differentiate between paraffinic, naphthenic and aromatic mineral oils.

There are applications in which an inexpensive mineral oil can be a sensible choice. However, it is fundamentally important to know that a high-performance synthetic oil is often the economically better alternative in the long term.

Price structure of mineral oil vs. synthetic oils

What is a polyalphaolefin oil?

Polyalphaolefins are synthetic hydrocarbons (Synthetic Hydrocarbons SHC) that are made from ethylene as the starting product. They are therefore often referred to as "synthetic mineral oils". Polyalphaolfins consist of isoparaffins with a different number of hydrocarbon side chains of the same length.

What is an ester oil?

Ester oils are synthetic lubricants. Esters are chemical compounds that mainly result from the reaction of acids (mostly organic acids / fatty acids) and alcohol with the elimination of water.

What is a polyalkylene glycol oil?

Polyalkylene glycols, also known as polyglycols, are polymerized ethylene oxide or propylene oxide units or combinations thereof that are initiated by addition to an alcohol. The proportion of ethylene oxide is decisive for solubility in water.

What is a silicone oil?

Silicone oils are polymerized siloxanes with organic side chains. They are made by chemical synthesis. The main component is silicon. Due to their excellent creeping and spreading properties, they are used as lubricants, defoamers, sealing and hydraulic fluids or as high-quality lubricants. Silicone oils are clear, colorless, odorless and tasteless and non-toxic.

What is a perfluoropolyether oil?

Perfluoropolyether oils (PFPE) are synthetic oils made up of carbon, fluorine and oxygen. They are used under extreme loads (e.g. at high temperatures, pressure) and are largely resistant to aggressive media.

Which base oils can be mixed with one another?

The following table serves as an initial guide. In order to be able to make a reliable statement, it is always advisable to have a miscibility test of the two oils carried out by your lubricant supplier.

What are additives?

Additives are oil-soluble additives that are incorporated into an oil during manufacture to improve its chemical and physical properties.

What additives are there for industrial oils?

What are solid lubricants?

Solid lubricants are the smallest particles and flakes that are incorporated into lubricating oils, lubricating greases and lubricating pastes as additives. The fact that these slide easily on each other reduces friction. The most common solid lubricants are graphite, MoS2, Ceramic and PTFE.

What are the properties of additives and solid lubricants?


Would you like to delve deeper into the topics of tribology, lubrication technology and lubricants?

Use the training courses offered by Klüber Lubrication:

We offer two-day training courses in Munich two to three times a year. Alternatively, you can also order individual training courses tailored to your needs on the subject of "Lubrication and lubricants", which will then take place at your company.

Do you have any questions or would you like advice?
Klüber Lubrication has more than 90 years of experience in the areas of friction optimization and specialty lubricants. We advise you personally on your specific requirements for refrigeration compressor oils.

How to contact us:
Michael forehead white
Email: [email protected]
Phone: +49 89 7876-501

Website: www.klueber.de

Publisher and copyright: Klüber Lubrication Deutschland SE & Co. KG
Reprinting, including excerpts, is only permitted if the source is cited and a specimen copy is sent and only after consultation with Klüber Lubrication Deutschland SE & Co. KG. The information in this document is based on our general experience and knowledge at the time of publication. They are intended to give the technically experienced reader tips for possible applications. However, the information does not contain any assurance of properties and no guarantee of the suitability of the product for the individual case. They do not release the user from testing the selected product in the application beforehand. All details are guide values ​​that are based on the lubricant structure, the specified application and the application technology. Depending on the type of mechanical, dynamic, chemical and thermal stress, lubricants change their technical values ​​depending on pressure and time. These changes can influence the function of components. We generally recommend an individual consultation and, on request and if possible, will be happy to provide samples for tests. Klüber Lubrication products are continuously developed. Klüber Lubrication therefore reserves the right to change all technical data in this document at any time and without prior notice.

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Munich District Court, HRA 84883