Lubricants

A lubricant (colloquially, lube) is a substance (often a liquid) introduced between two moving surfaces to reduce the friction and wear between them. more...

Home
Bath & Body
Dietary Supplements,...
Hair Care
Hair Removal
Health Care
Body Enhancers
Family Planning
Condoms
Assortments, Mixed Lots
Colored, Scented
Extra Sensitive
Flavored
Maximum Strength
Natural Feeling
Other Styles
Ribbed
Fertility Monitors
Impotence Aids
Lubricants
Other Family Planning
Ovulation Kits
Pregnancy Tests
Feminine Hygiene
First Aid
Hot & Cold Therapies
Other Health Care Items
Pill Cases, Boxes
Relaxation Aids
Sleeping Aids
Smoking Cessation
Makeup
Massage
Medical, Special Needs
Nail
Natural Therapies
Oral Care
Skin Care
Vision Care

A lubricant provides a protective film which allows for two touching surfaces to be separated, thus lessening the friction between them. One of the single largest applications for lubricants, in the form of motor oil, is to protect the internal combustion engines in motor vehicles and powered equipment.

Typically lubricants contain 90% base oil (most often petroleum fractions, called mineral oils) and less than 10% additives. Vegetable oils or synthetic liquids such as hydrogenated polyolefins, esters, silicone, fluorocarbons and many others are sometimes used as base oils. Additives deliver reduced friction and wear, increased viscosity, improved viscosity index, resistance to corrosion and oxidation, aging or contamination, etc.

Non-liquid lubricants include grease, powders (dry graphite, PTFE, Molybdenum disulfide, etc.), teflon tape used in plumbing, air cushion and others. Another approach to reducing friction and wear is to use bearings such as ball bearings, roller bearings or air bearings, which in turn require internal lubrication themselves, or to use sound, in the case of acoustic lubrication.

Lubricants such as 2-cycle oil are also added to some fuels. Sulfur impurities in fuels also provide some lubrication properties, which has to be taken in account when switching to a low-sulfur diesel; biodiesel is a popular diesel fuel additive providing additional lubricity.

In addition to automotive and industrial applications, lubricants are used for many other purposes, including as a personal lubricant, bio-medical applications (e.g. lubricants for artificial joints) and others.

Purpose

Lubricants perform the following key functions.

Keep moving parts apart; Reduce friction; Transfer heat; Carry away contaminants & debris; Transmit power; Protect against wear; Prevent corrosion;

Keep moving parts apart

Lubricants are typically used to separate moving parts in a system. This has the benefit of reducing friction and surface fatigue together with reduced heat generation, operating noise and vibrations. Lubricants achieve this by several ways. The most common is by forming a physical barrier i.e. a thick layer of lubricant separates the moving parts. This is termed hydrodynamic lubrication. In cases of high surface pressures or temperatures the fluid film is much thinner and some of the forces are transmitted between the surfaces through the lubricant. This is termed elasto-hydrodynamic lubrication.

Reduce friction

Typically the lubricant-to-surface friction is much less than surface-to-surface friction in a system without any lubrication. Thus use of a lubricant reduces the overall system friction. Reduced friction has the benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. Lubricants may contain additives known as friction modifiers that chemically bind to metal surfaces to reduce surface friction even when there is insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve train in a car engine at startup..

Read more at Wikipedia.org