Industrial Lubricants & Lubrication system

Industrial Lubricants & Lubrication system
General Introduction of Lubrication
a. What is lubricant?
Lubricant is a substance, which is used in between two matting parts, so that they can
move without any friction & they can keep them cool.
In any machine or equipment, it is always seen to use lubricants.
There are many machine/ equipment used in industries.
So, huge quantity of lubricants is used in industries.
Wide selection of lubricating materials is available.


b. Basic types of lubricants:
solid
semi-solid
liquid
Gaseous


c. what are the functions of lubricant?
To reduce friction
To prevent wear
To prevent adhesion
To aid in distributing load
To cool the moving elements
To prevent corrosion


d. What is lubrication?
The process of applying lubricants is called lubrication.


e. Conclusion:
Different lubricants have different properties.
Great care is to be taken in choosing lubricants
Methods of application are also to be properly selected.
Inadequate use of lubricants can damage a machine or equipment.
Any maintenance personnel are required to be well conversant in using lubricants
During down time as well as in running condition.

Solid Lubricant, Lubricating oil & their properties

a. Introduction
Solid lubricants & lubricating oils are applied between two moving parts to minimize friction & wear. Different types of lubricants are used in different machine/equipment. As such is importance to know their properties properly.

b. Solid lubricant
* Graphite
· Purified graphite consists of 99.9% pure carbon.
· It fills the irregularities of the material so that the surface often becomes much smoother.
· Powdered dry graphite is used lubricating specifically in fine mechanism.

* Molybdenum disulfide
· Also known as ‘molykote’ is a compound of one atom of molybdenum & two atom of sulphur.
· It reduces the friction between metals considerably. The coefficient of friction varies between 0.05~0.09 depending on load.


c. Lubricating Oil
* Base oil
· The mineral oils which are the product of the refinery can be sub-divided in order of increasing thickness. For example spindle oil, Cylinder oil, machine oil etc.
· Base oil can also be sub divided accordingly to their predominant properties, namely paraffinic, Napthinic, Aromatic.
· To obtain the write properties, some lubricating oils are made from more than one base oil. The base oil are mixed in carefully measured proportions with the necessary additives.
* Additives
· The additives or doves are chemical combination that improve the properties of base oils. In practice lubricating oils are used for a range of very different purposes. Turbine oils for example must have very high resistance to ageing. Engine oils must be proof against high temperatures & have a good detergent capacity.

d. Properties of Lubricating oils
· Colour
· Specific gravity
· Viscosity Index
· Pour point
· Flash point
· Ageing
· Foaming
· De-emulsification


Different Types of Grease & Their Properties

a. Introduction
· Grease is a semi-solid lubricant.
· Generally grease is used in low speed machines.
· Its retention capacity is more than liquid lubricant.
· It can be used at any angular positions of the rotating parts.
· It also protects the rolling elements from foreign particles, damp & water.
· So grease is also a vital lubricant.


b. Main Components of grease
· Mineral/Synthetic oil
· Soap/thickener & Additives
· A typical grease consists of approx. 80% oil, 10% thickener & 10% additives.

C. Main Properties of Grease
1. Dropping point
When grease is heated it becomes softer & gradually in liquid form. To determine
the dropping point, an amount of grease is placed in a nipple & gradually heated
until the first drop of oil falls. So, the dropping point of grease is the temperature
at which first drop of oil falls from the grease.
2. Consistency
when the quantity of soap is the grease & the viscosity of the oil are changed the
hardness or consistency of the grease also changes accordingly. The indication soft,
weak, hard for a grease can not be differentiated manually. Practically consistency of grease is expressed by the penetration value.
It is measured according to NLGI (National Lubricating Grease Institute) & ASTM
(American Society for Testing & Materials) - D217:
A round cup is filled with grease (25ºс) then a cone is dropping from a certain height. The deeper the cone penetrates, and then the grease is weaker. The resulting penetration is measured in tenths of millimeter, which is expressed as the work penetration value.

The NLGI classification of grease consistency
NLGI Consistency Number Work penetration(1/10 mm), 25ºс Appearance
000 445-475 Semi-fluid
00 400-430 Semi-fluid (Very Soft)
0 355-385 Semi-fluid (Grease gum)
1 310-340 Soft (Grease gum)
2 265-295 Medium: Common grease(Grease gum)
3 220-250 Medium hard (Grease cup)
4 175-205 Hard (Grease cup)
5 130-160 Very hard (Grease cup)
6 85-115 Block type


Different types of grease & their properties
Name of Grease
NLGI
No.
Drop
Point
(ºC)
Work penetration
At 25 ºC
Usable
Temp.
Range(ºC)
Remarks
a) Ca-base
Normal

Heavy


Underwater

0

2


000

93

100


80

355

265


450

-12~60

-12~60


-40~60
Soft & water resistant suitable for chassis lubrication

Good mechanical stability & excellent water resistant

Very soft, with exceptional resistance to wet conditions
b) Na-base
2
150
270
-30~80
Not suitable at wetted area less costly
c) Li-base
Multipurpose
Li-complex

2

2

150

260

280

265

-30~105

-40~150
All purpose bearing & wheel lubrication
High performance bearing grease at high temperature
d) Bentone base
3
Indefinite
245
-7~260
High temp. grease with anti-oxidation inhibitors
Others







Different types of lubricating oil & their place of use
a. Introduction
The lubricating oils most commonly used today are composed of base oil & additives.
Base oils are prepared by several available refining processes from natural occurring hydrocarbon. Hydrocarbon oils are used because:
· They are available in a range of viscosity that gives a wide choice of load, speed & temperature condition of the designer.
· They give a low coefficient of friction & have low compressibility.
· They are reasonably effective in carrying away heat
· They are inexpensive lubricants.

Additives are chemicals, which are frequently blended with petroleum or synthetic oils to modify or enhance certain characteristics relating to performance. Their concentrations in finished lubricants may vary widely, from only a few parts per million to appreciable percentages.


b. Types of lubricating oils

Hydrocarbon lubricating oils fall into two main categories:
· Paraffinic oils have high pour points (because of the wax they contain), high viscosity indexes & resistance to oxidation.
· Naphthenic oils have low pour points relatively low viscosity indexes & oxidation stability.

Synthetic base lubricating oil may cost several times as much as hydrocarbon oils but they are necessary for some specialized applications, like aircraft gas turbines where resistance to degradation at temperature of up to perhaps 300 ºC is necessary.

Lubricating oil also can be classified by its viscosity, the type of performance tests it can pass, the type of mechanism for which it is intended & the industry in which it is used. Here we discuss the most common lubricating oil categories & their place of use:

C. Circulating Oils
· Circulating oils are used in systems where oil is circulated to many individual bearing in order to remove large quantities of heat & contaminants.
· These are probably among the highest quality lubricating oils available today.
· They are obtained over a comparatively wide range of viscosities, i.e. from around 21 to 550 centistokes viscosity at 100 ºF.
· In this category are included steam turbine-grade oils, hydraulic oils, steel-mill circulating oils, paper machine circulating oils, heavy-duty internal combustion oils.
· Circulating oils contain additives to enable resist oxidation & to retard rusting in the system.
· They also usually contain foam dispersant.

d. Gear oils
· These are be straight mineral oils of widely varying viscosity or compounded oils containing, extreme-pressure (EP) additives to improve the film strength & load carrying ability.
· Straight mineral oils for plant service range normally from SAE 80 to 250. They are suitable for enclosed gear sets of spur, bevel, helical, spiral bevel, herringbone, or annular type where there is provision for splash or force-feed lubrication.
· They lower viscosity grades are used for low temperature service, the heavier grades, i.e. SAE 140 or 250, being selected for service, which will normally range above 100 ºF.
· Automotive gear oils often have higher EP performance & lower pour points than industrial gear oils.
· Industrial gear oils often have superior resistance to oxidation & rusting.

e. Engine Oils
· Engine oil meet different levels of performance requirements of the American petroleum institute (API).

Filler

Introduction:
The original purpose of adding filler to the fibre furnish was as a cost saving diluents with the quantity limited by the commensurate loss in strength properties. Now this use has become secondary to the selection & incorporation of designed fillers to achieve specific improvements in paper quality. Depending upon the performance characteristics of the particular filler as well as the % added these materials can enhance the physical, optical, price. Performance & esthetic properties of the finished paper.
The more common practice is to choose materials that provide the opportunity for both cost & quality improvement.

Functions of fillers:
Fillers can be useful in most types of paper they are especially beneficial in printing & writing papers. The addition of fillers can contribute the following properties to paper.
Better formation & sheet structure through improved fibre distribution & the fill in of void areas.
Improved texture & feel resulting from a smoother surface & more uniform composition.
Increased opacity from both the filler per se & its impact on fibre debonding.
Better prinlability for a number of reasons including a more uniform & smoother surface for receiving the impression. Less showthrough because of higher opacity increased & more rapid acceptance of ink as well as faster ink setting. Reduced ink penetration, feathering & strike through, improved dimensional stability.
Cost savings interrelated with the type & amount of filler used.

The performance of a filler is dependent upon essentially two factors, the properties of the material & the manner in which it is used.

Important characteristics of filler pigments:
Particle size & shape, specific surface area, light absorbing properties, particle charge, refractive index and abrasion are some of the more important characteristics of filler pigments.
Particle size: the optical properties of any pigment are strongly affected by the particle size distribution & the degree of agglomeration of the pigment. Results show that a narrow particle size distribution promotes good light scattering efficiency.
The mie theory predicts that the maximum scattering of light is obtained by spherical particles one half the wavelength of light or approximately 0.2 to 0.3 μm in diameter.
Spherical Particles→ Plastic pigment, titanium dioxide etc
Non spherical particles→ clay, talc, precipitated CaCO3 etc.
Particle shape : When particles deviale from a spherical shape their optimum equivalent spherical diameters may be outside the range predicted by the Mie theory. Also the packing orientation of the pigment will greatly influence its alignment within the fibre matrix of the sheet.
Specific surface area: the particle size, shape & degree of agglomeration all influence the specific surface area of a pigment. The pigment surface area aids in light scattering & also influences the strength & printing characteristics of the paper.
Effect on paper strength: filler pigment will tend to cause a reduction in the strength properties of the sheet. Min general the higher the specific surface area the weaker the paper will be at an equal degree of loading. The primary cause of this weakening effect is related to the pigments interfering with fibre to filler bonding within the sheet.
Abrasion: highly abrasive pigments will cause excess wear of both paper machine wires & printing plates; cutter & trimmer knives in the converting area of the mills are also susceptible to excess wear. The abrasiveness of a pigment is principally caused by two factors. The crystalline nature & hardness of the pigment is of importance to the abrasiveness of the pigment (strength of the atomic bonds, spatial arrangement, impurities etc) along with its physical properties (size, particle size distribution, shape surface area etc). Impurities such as quartz can cause severe abrasion problems & large particles tend to be more abrasive than smaller particles of the same crystalline form.


Types of filler
Kaolin clay: 39% Al2O3, 46% SiO2 & 13% H2O remaining impurities.
CaCO3: Despite its high brightness & other benefits for many years the traditional acid paper marking systems in most instances precluded the use of CaCO3 as a paper filler. Aside from cigarette paper where the incorporation of high % of precipitation CaCO3 as a filler serves to control the paper porosity & burning rate, the uses for CaCO3 in the paper were quite limited.
TiO2: TiO2 has the highest refractive index of any white pigmentary material. Its extremely high price.
Talc: In the US the major use for talc in paper is to control pitch. Becase of its unique properties. There is a limited but growing interest in high purity talc as a paper filler.
Unfortunately in commerce the term talc, perse , is commonly used to cover a wide range of mineral mixtures. Some of which contain very little pure talc. Most of these materials are not suited for use in paper & therefore are not refrred to in what follows