Oil separation
Oil separation as a percentage of weight is measured in accordance with DIN 51817 whereby the lubricating grease to be inspected is admitted with pressure and temperature.
Oxidation
Oxidation is a combustion process. The addition of oxygen to certain elements or molecules occurs in this process. In the case of hydro-carbons jellification, the formation of lacquer, polymers, corrosive radicals etc. arise. Measurable variable for the stipulation of the consistency (ductility) of lubricating greases. In the case of lubricating fats it is the distance which a cone of a certain dimensions penetrates vertically into the sample to be investigated under stipulated conditions (DIN ISO 2137 or DIN 51 804).Static penetration: Penetration of lubricating grease sample, which was not pretreated in the grease shaper, measured at +25°C.Worked penetration: By the term worked penetration we mean the cone penetration, which is determined immediately following the treat-ment of the sample with 60 double cycles within a minute in the lubricant shaper, at +25°C.
Penetration
The Press-Fit-Test provides information about the behaviour and the adhesion of solid lubricants at very high pressure
and at a low sliding speed. The friction figure µ is measured and it is determined whether stick slip arises. Both results
are important for the applications in the event of installation work (e.g. press manufacture) or in the case of gliding
channels and guides (e.g. tool machines).
Press-Fit-Test Room temperature (RT)
Room temperature; defined in accordance with DIN 50014 = +23°C with 50% relative air humidity
The salt
spray test simulates a salty climate in accordance with DIN 50021 SS, whereby coated metal plates are
exposes to a defined salt
spray. It is monitored after how many hours traces of rust arise. Is applied to assess the corrosion-preventing properties of roller bearing lubricants. In this process water is added to
the grease and examined for evidence of corrosion in self-aligning ball bearings with a defined running duration and stop
periods in accordance with DIN 51802. If no corrosion emerges during the visual inspection of the test rings then the
corrosion level is 0. In the event of very extensive corrosion the maximum mark is 5.
SKF EMCOR procedure
Are generally only used and required for lubrication tasks under extreme conditions (e.g. during operation in a mixed friction area). The most well-known ones are graphite, molybdenum sulphide, different plastics (e.g. PTFE), heavy metal sulphides, etc. The determination of the fixed lubricants is carried out in accordance with DIN 51 831 and DIN 51 832.
Solid lubricant Speed characteristic value
The speed characteristic value is a guiding value stating at which peripheral speeds lubricant can be used in roller bearings. Results on grease inspection machines, the basic oil viscosity and practical experience form the basis for the statement of the value
Stick slip
Stick slip arises if the lubricant does not have a sufficient separation grade as the initial friction is higher than the motional friction. By contrast with natural oils, e. g. mineral oils, vegetable and animal oils, they are gained by means of chemical processes. In this way specific advantages can be gained such as the low tendency to coke, a low pour point, good resistance to chemicals and often excellent viscosity-temperature characteristics. Synthetic hydrocarbons, ester, polyglycol, fluorinated oils and silicon oils are for example used as lubricants.
Synthetic oils
Thread friction is determined on a screw testing stand. In accordance with DIN 946 you obtain the friction figure µ
of a screw connection when tightening screws and screw nuts. The thread dimensions, material and type of surface
must be stated.
Thread friction Tribology
The area of tribology comprises the scientific research and technical application of friction, wear and lubrication whilst taking account of the construction, material science, authority regulations etc. USDA-H1: USDA-H2: Designation class for tested and authorised lubricants, which can come into occasional, technically unavoidable, contact with foods. Designation class for lubricants which may not come into contact with foods. United States Department of Agriculture
USDA
The viscosity of an oil as a measure of the internal friction is determined using different measurement devices depending on the product. The kinematic viscosity is determined using the Ubbelohde viscometer at +40°C and at +100°C in order to be able to determine the viscos-ity reduction at higher temperatures.
Viscosity
VKA is the abbreviation for Vierkugelapparat (four ball tester for luboils) by means of which the welding load and
wear is measured in the event of punctual contact. DIN 51350 describes the test process. The welding load [N]
is the point at which the welding of the individual balls with one another occurs. The wear characteristic value [mm]
is the average diameter of the spherical caps which is formed at a constant load following a defined testing time.
VKA Water resistance
There is a static and a dynamic test to test the behaviour of lubricating greases towards water. It is investigated how the influence of water affects the lubricating grease at different temperatures (DIN 51 807).
Wear
Arises after penetrating the lubricating film if the sliding partner touch one another and rub against one another.
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