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Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A

Additive

Extra ingredient in lubricants, corrosion protection products and maintenance products used to achieve specific product properties


Ageing

Chemical modification voer time of substances in use due to the effects of heat, light and oxygen
B

Baseoil

Carrier fluid for pastes, greases and oils


Biodegradable

Refers to a substance that can be decomposed by micro-organisms

Breakaway ratio

The ratio of release torque to tightening torque. For high-temperature screw pastes, this value is determined after tightening an M10 or M12 bolt (material: A2-70) using a torque of 40Nm or 70Nm and exposing it to a temperature of between +200C and +650C over a period of 100 hours.
C

C

As defined in DIN 51517, Part 1: designation indicating that a substance is suitable for use as a lubricating oil

CL

As definded in DIN 51517, Part 2: designation indicating that a substance is suitable for use as a circulating oil (C-oil + corrosion protection additive)

CLP

According to DIN 51517, part 3: designation indicating taht a substance is suitable for use as an enclosed industrial gear oil (CL-oil + EP additive)

Coating thickness

This has a decisive influence on lifespan of the corrosion protection. Depending on the type of protective coating used, various measurement techniques can be used to establish the coating thickness, which is specified in µm.

Complex grease

Contains a thickening agent made from metal soaps of differing acids, which produces a higher drop point compared to greases made with simple soaps


Condensed water test

This test is one of several test methods used to evaluate a protective coating exposed to corrosive influences (DIN 50017 - Condensation water test atmospheres) and defines a test procedure using an alternating atmosphere in a climate chamber. The test result is specified as the number of hours until traces of rust occur.

Consistency

The consistency of a lubricating grease is the parameter used to quantify ist strength. As defined by DIN 2137, this is measured by the penetration depth of a standard cone. The classification according to NLGI (DIN 51818) ranges from very soft (Klasse 000) to very hard (Klasse 6). Standard lubrication greases are generally NLGI grade 2.

Corrosion

Reaction of a metal with its environment, which changes its properties and impairs the functionality of the component


D

DIN 51502

The aim of this standard is to ensure consistent designation of standard lubricants using a system of markings consisting of code letters and simple graphical symbols. The marking identifies characteristics including: type of lubricant, viscosity, consistency and operating temperature. Speciality Lubricants can only be described partially using DIN 51502

DN value

The DN value, or speed index, is an empirical standard value that indicates the permissible maximum rotational speed at which grease can be used in a roller bearing. The DN value is essentially  based on the pitch circle diameter (D+d)/2, but is also heavily dependent on the type of bearing/bearing assembly in question


Drop point

The drop point refers to the temperature at which a the thickener in a lubricating grease can no longer bond with the base oil, meaning that the grease is able to flow through the opening of a nipple in accordance with the test conditions defined in DIN 2176.

DVGW

Deutscher Verein des Gas- und Wasserfaches - German Association of Plumbers
E

Emergency lubrication

This is provided by solid lubricants under conditions of starved lubrication where there is insufficient lubricating grease or oil.

EP lubricants

Lubricants with "Extreme Pressure" additives, designed to improve resistance to pressure and wear protection properties

Evaporation loss

This is of particular interest for high temperature lubricants. The evaporation loss is investigated by holding the lubricant at an elevated temperature for a defined period as defined in DIN 58397. The oil lost to evaporation is measured as a percentage weight and should be as low as possible.
F

FDA

Food and Drug Administartion - the national authority responsible for foodstuffs and pharmaceuticals in the United States 

Flashpoint

The flash point is a measurement quantity applied to a flammable liquid that allows the level of fire hazard to be assessed. Depending on the type of product and the value of the flash point, the most common measurement methods are closed tester (defined in DIN 51755) and open cup (defined in DIN ISO 2592)

Fretting

Fretting occurs when the lubrication film is broken, causing surface roughness peaks to weld together


Fretting corrosion

This is corrosion that occurs at contact surfaces due to oscillating micro-friction action.
Immediate rust formation on worn steel particles

Friction coefficient, µ

Coefficient of friction.

FZG gear test rig

The FZG gear test rig is used to examine oils and greases specifically with regard to their suitability as lubricants in enclosed gears. The wear is determined for each level of load, with the result being given by what is known as the "scuffing load stage". The test method is descrobed in DIN 51 354
H

H

As defined in DIN 51524, Part 1: designation indicating that a substance is suitable for use as a hydraulic oil

Heavy metals

All metals with density > 5g/cm3.

High temperature lubricant

Often referred to as HT lubricant, this is suitable for continous use at temperatures above +140°C


HL

DIN 51524, Part 2: designation indicating that a substance is suitable for use as a standard hydraulic oil (H-oil + corrosion protection additive)

HLP

DIN 51524, Part 3: designation indicating that a substance is suitable fo use as a high performance hydraulic oil (HL-oil + EP additives)

Hydrodynamic lubrication

This refers to situations where sliding partners are completely separated from each other by a liquid lubricting film


I

ISO

International Standardization Organisation
K

KTW

Guideline for organic materials in contact with drinking water (in Germany)


L

LGA

Landesgewerbeanstalt Nürnberg (State Trade Institute in Nuremberg) including the Institute für Lebensmitteltechnik (Institute of Food Chemistry)

Low-temperature lubricant

A lubricant that is suitable for continuous use at temperatures below -20C.

Lubrimeter test rig

This is a type of test rig used to measure the friction coefficient, wear and operating temperature for a lubricant with different materials under varying loads and at different sliding speeds.
M

Mixed friction

Lubrication condition in which partial dry friction occurs at the same time as hydrodynamic lubrication.

MoS2

Chemical formula for molybdenum disulfide (mineral molybdenite).

Mox-Active

Mox-Active (OKS registered trademark) is an additive used in lubricants to facilitate levelling of otherwise rough metal surfaces at the lubrication points, thereby producing a highly effective tribological surface finish. This means that run-in times are much shorter and friction and wear are considerably reduced.
N

NLGI

National Lubricating Grease Institute (USA).

NSF classification

The National Sanitation Foundation issues NSF registration numbers for lubricants that have a composition in accordance with the positive list of substances from the United States Food and Drug Administration (FDA). The classification H1 indicates a lubricant that may be used in situations where it is technically impossible to exclude the possibility of contact with foodstuffs. The classification H2 indicates a lubricant that may be used in situations where there is technical means by which it could come into contact with foodstuffs.
O

Oil separation

Oil separation is measured in weight percent, as defined in DIN 51817, with the lubricating grease under test being exposed to pressure and heat.

Oxidative stability

The oxiditative stability of a lubricating grease is a measure of its resistance to reaction with pure oxygen. As defined in DIN 51808, the grease must be exposed to the oxygen for a defined period (e.g. 100 hours) at a specific temperature (e.g. +99C or +160C) and under pressure. The result of the test is given as the reduction in pressure in Pa (Pascal) of the oxygen, which represents the degree of oxidation.
P

Penetration

Measurement quantity used to determine the consistency of lubricating greases.

Pour point

The pour point of an oil is measured as defined in DIN ISO 3016. This point lies a few degrees Celsius below the recommended minimum application temperature.

Press-fit test

This test provides information on the behaviour and level of adhesion of solid lubricants under very high pressure and at low sliding speed. The test involves measuring the coefficient of friction, µ, and determining whether stick-slip occurs. Both results are important with relation to assembly operations (e.g. press-fit assembly) and for slide bars and guides (e.g. machine tools).
R

RT

Room Temperature; as defined in DIN 50014 = +23C at 50% relative humidity.

Running in

Process of smoothing of surface roughness in new sliding contact surface combinations


S

Saponification

This is the process of thickening a base oil to turn it into a lubricating grease by means of a reaction between metal hydroxides (Li, Ca, Al, Ba) and acids (preferably fatty acids).

Silicon oils

These oils are produced using synthesising techniques. They have particularly good viscosity-temperature properties, are stable at low and high temperatures and are resistant to aging. Excellent separating properties. Outstanding lubricant for plastics and elastomers. Names such as polydimethylsiloxane or polyphenylmethylsiloxane describe the special structure of the molecular groups.

SKF-EMCOR method

This is a method that is used to measure the corrosion protection properties of lubricants for rolling-bearings. This is achieved by adding water to the grease, which is then tested for corrosion over a defined period using self-aligning ball bearings run at a fixed speed and held at rest for specific periods of time, as defined in DIN 51802. If there is no visible corrosion of the test rings then the degree of corrosion is rated 0. The maximum rating is 5, which indicates very heavy corrosion.

Solvent

A liquid that can dissolve other materials without chemically altering them


Stick-slip

This occurs when the lubricant does not provide a sufficient separating effect, because the start-up friction is higher than the kinetic friction.

Synergism

Positive interaction of several components, whereby the cumulative effect of individual characteristics is multiplicative rather than additive.

Synthetic oils

Oils produced by means of chemical processes, as opposed to those extracted from the natural environment (mineral oils, animal and vegetable oils). Certain advantageous properties can be achieved, such as low tendency to carbonise, lower pour point, good resistance to chemicals and, often, excellent viscosity-temperature properties. Lubricants of this type make use of, amongst other substances, synthetic hydrocarbons, ester, polyglycols, fluorinated oils and silicone oils.
T

Thread Friction

Thread Friction it determined using a screw test rig. According to DIN 946, the coefficient of friction for a threaded connection should be determined by tightening the fasteners and nuts. Threads dimensions, material and type of surface must be specified
U

USDA

United States Department of Agriculture.
V

VCI

Volatile Corrosion Inhibitor (vapour-phase inhibitor) is an environmentally-friendly anti-corrosion additive.

VG

Abbreviation for Viscosity Grade, which specifies the viscosity range of a lubricating grease.

Viscosity

Viscosity is a measure of the resistance of a fluid to flow due to the action of internal friction. The most important influencing factor on viscosity is temperature. Viscosity decreases as temperature increases, and vice versa. The allocation of viscosity grades is defined in DIN 51519. The higher the number, the thicker the fluid.

VKA test

The four-ball test rig (German: Vierkugelapparat) is a piece of equipment that is used for testing lubricants at high surface pressures in the mixed-friction zone. As defined in DIN 51350, the VKA consists of a rotating ball bearing that slides against three stationary ball bearings. To test the maximum load capacity of the lubricant, a test force is applied to the rotating bearing, which is increased in stages until welding occurs in the four-ball system. An additional VKA test method is used to determine the wear coefficient of a lubricant under defined test conditions (test force, speed, time).
W

White oil

Paraffin-based mineral oil, highly refined to remove unstable components.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z