Tribology originates from Greek word TRIBOS meaning "a rubbing" or friction and word LOGOS – science. Tribology is scientific discipline which researches appearances and processes on interacting surfaces that are in relative motion, i.e. in direct or indirect contact. Basic aim of tribology is to study conditions for optimal conducting of production processes, for energy consumption reduction, reduction of maintenance costs due to machine wear and increase of mechanical system reliability.
In other words, tribology is the study of lubrication.
The quantity of lubricant in the bearing is recommended by bearing manufacturer. However, in rare cases the necessary quantity of lubricating grease is over one half of maximum possible quantity that is possible to be filled into the bearing.
NLGI - NATIONAL LUBRICATING GREASE INSTITUTE - is the association which defines lubricating greases quality and directly determines type of lubricating greases according to consistency (hardness). In practice, lubricating greases are divided into: semifluid, soft, medium hard and hard lubricating greases.
If it is the manual lubrication then nothing drastic happens, but in central lubrication big problems, even great damages may happen.
They are always used when equipment producer or when application conditions require that: in very low temperatures, very high temperatures, significant influence of water and moisture, impurities, significant presence of vibrations, high speed of revolutions in assembly blocks and very high loads.
FAM lubricating greases do not have negative impacts on common sealing materials.
Yes, they are compatible with the standardized ones.
SAE - Society of Automotive Engineers - society that prescribes standards that define engine oil viscosity. Based on these standards, oils are sorted in accordance with viscosity grade which directly influences the application of the oil.
The oils marked with letter "W" (winter) are monograde oils for winter operating conditions (eg. SAE 5W, SAE 10W, SAE 15W...). Among other things, standard efines oil properties in low and in high temperatures, thus reliability of engine start is provided as well as fast engine oiling and oil behaviour during full exploitation. Oils without letter "W" (eg. SAE 10, SAE 20, SAE 30, SAE 40 ...) are monograde oils for summer operating conditions, with properties required for such application. Combination of properties of the two oil types (winter and summer) resulted in multigrade oils which are applied for wide temperature range of operating conditions (eg. SAE 5W-40, 10W-40, 15W-40 ...).
API - American Petroleum Institute - institution that defines engine oil quality levels worldwide. There are two groups of standards:
Letters are added with S and C. Alphabetical growing order indicates higher oil quality.
ACEA - European Automobile Manufacturers' Association - issues three types of standards:
Apart from the mentioned letters arabic numerals are added. Growing order indicates higher oil quality.
EURO - Exhaust emission is defined by regulations known as EURO standards. This is the area with very strict demands particularly in diesel engines. For example, EURO III standards were published in 2000., EURO IV standards were published in 2004., EURO V standards were published in 2008., and EURO VI standards are expected in 2011.
ILSAC - Association of Japanese car manufacturers, Ford, General Motors and Daimler Crysler publish their own requirements by which necessary engine oil quality level is defined, and they are in accordance with API and ACEA specifications.
For example, ILSAC GF-5 corresponds to quality API SN. Certainly, together with the mentioned standards and specifications, famous car manufacturers have their additional requirements for engine oil quality.
The first and basic prerequisite is to observe the recommendations of motor vehicle manufacturer and those recommendations must be observed. The following also must be taken into account: age of the vehicle, engine condition, driving modes and fuel quality. Of course, change periods differ for different oil qualities, which also must be taken into account.
This dilema is solved to a greater degree during engine oil selection. Besides the mentioned criteria for selecting engine oil, attention should be paid to oil consumption during exploitation (which is measurable), change in oil smell, possible change in engine sound, increase of engine operating temperature and start itself. These and other empirical observations may be very helpful when determining oil exploitation period for specific vehicle, of course in absence of laboratory checks.
Compared to mineral oils and to a lesser extent to semisynthetic oils, generally speaking, synthetic oils have better properties regarding:
Legally speaking, engine oils of different producers, with the same viscosity grade and the same base (mineral, semisynthetic and synthetic) must have the ability to be mixed, i.e. must be compatible. In practice, in such situations one must be careful and such situations should be avoided. Oils of different viscosity grades and different bases should not be mixed.
Yes, it can be done after changing the old oil and oil filter. Their mixing is not recommended.
No, if the old oil and filter are changed. Their mixing is not recommended.
It is environment friendly, the driving is more economical, the combustion is better and more complete and engine oil contamination is lower.
With application of high quality oils small saving in fuel consumption can be expected.
That hazard exists only if sealings are not produced from material defined in accordance with world standards for indicated purpose.
The most important issue is environment protection (pollution of water, air and soil must be prevented). All oils must be collected, stored and processed in legally prescribed manner.
Cost structure indicates that lubricants are not big expense. For example, total costs of the car that passes 20.000 km annually, are composed as follows:
Structure of variable expenses is as follows:
Expenses of lubricants which amount to 1% of variable costs are very low i comparison with all other costs. Therefore there is no reason to skimp on choosing the lubricant.
On the contrary, oil quality has special effect on total maintenance costs and with careful selection significant savings can be achieved.
Proper selection of high quality modern engine oil provides the following:
In very worn out engines, OEM recommendations are relative in a way. Good solution can be the application of oil which is one viscosity grade above the recommended one. Depending on worn-out degree, lower oil consumption is achieved, better working pressure and sealing. Besides that, potential smaller entering of fuel into oil is achieved and better engine protection is achieved. Often, viscosity grades 20W-50 and 20W-60 are very good solution. Naturally, period of oil exploitation under given circumstances is shortened. Shortening of change period is in the range of 20% to 40% of the prescribed one.
For heavy duty operating conditions in relatively new machines, if longer oil change period is required, semisynthetic and synthetic oils are better option. In contrast to the mineral oils, these oils are more resistant to high temperatures, oxidation and polymerization as well as to acidic combustion products. Their coke value is much less and they have better shear stability, therefore they keep the necessary viscosity longer. They are, certainly, applicable to new mechanization where appropriate viscosity grades are prescribed. Change intervals in such oils are significantly higher and they are economically more payable.
Generally speaking, the ration of engine oil change interval of the same or similar specifications is:
mineral : semisynthetic : synthetic = 1 : 1,5 : 2
Considering that price ratio is more favourable, it is easy to find economic reasons for application of better quality oils.
When choosing between monograde and multigrade oils, in most cases multigrade ones should be selected. Multigrade oils have stable viscosity and they are applicable in all weather conditions. They have the advantage in different driving modes and their temperature is more stable. Monograde oils are applicable in unified exploitation modes, primarily in stationary engines.
Similar recommendation is valid also for transmission oils. Wherever it is possible, multigrade transmission oils should be applied. The most frequently applied grades are SAE 80W-90 and SAE 85W-90.
Oil filter is important factor which significantly influences oil change period. Very frequently it is the weakest point in the oil system, which is sometimes forgotten. Besides the efficiency of filtering and letting oil into circulation flows, which is very important in engine lubrication, oil filter keeps the particles of metal wearing which may have catalytic effect on the process of oil degradation.
Basic functions of cutting fluid are cooling, lubrication and chips removal. By cooling and lubrication the temperature which occurred during cutting process is controlled, tools and by chips removal, tool wear is reduced to minimum.
The selection of suitable (optimum) metalworking product for certain machining process is complex problem. When solving it, multidisciplinary approach is necessary and the following things must be taken into consideration:
Material machinability defines the degree of easiness with which it can be machined and it depends on:
From the viewpoint of material machinability, products with good cooling properties are used:
Emulsions and low concentrate content solutions are used here.
Products with good lubricating properties are used:
Cutting oils or emulsions are used as well as high concentrate content solutions.
When selecting metalworking product, attention should be particularly paid to their anticorrosion properties especially in operations of machining aluminium, copper and magnesium alloys.
Metalworking product must not stain (leave traces - stains) and must not cause corrosion on machining items, and not only on machined surfaces. Metalworking product should protect machining items from corrosion during cutting, during transportation from one machine to another in the production process and while machining item is waiting in the store house to be built into the product.
Acceptability, from the point of view of operator who performs the machining procedure, is very important characteristics of the metalworking product, which should be taken into consideration when selecting the product for certain machining process. Metalworking products must be clean, must have pleasant odour, during their usage poisonous vapours or gases must not appear and they must not harm the operator`s skin. Emulsions and solutions must be sufficiently stable and resistant to bacteria development, especially in summer months
There are primary and secondary requirements which should be met.
Tribological requirements are based on:
Lubricant with good tribological properties provides:
Ecological requirements are:
Economical requirements include:
When selecting metalworking product it is important to remember their enormous influence on life expectancy of the tools, energy consumption during cutting process, machined surface quality and machining costs.
Basic goal of every technical system operation is achieving long period of time in which the system works properly without failures. By adequate selection and regular application of lubricant, downtime and maintenance costs can be reduced
In order to make the right selection of cutting oil, the following thing should be taken into consideration: