Grease Plant
GREASE MANUFACTURING PROJECT
Outstanding characteristics of greases manufactured in our projected grease kettle or say grease plant are:
| Purity | Complete absence of corrosive or abrasive ingredients that would be harmful to Bearings. Only highest quality fats are recommended to obviate rancidity. |
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| * | Uniformity | Raw materials and Finish products Quality Control, Uniformity in Process Parameters, consistency in all physical and chemical properties. Lube oils and Recommended are carefully selected to give excellent lubrication characteristics. The process parameters have been finalized and adopted after large number of Production batches. |
| Stability | Retention of homogeneity throughout their use and in storage. | |
| * | Extra Qualities | Extra desirable qualities have been imparted to the greases— either by way of special manufacturing processes or by Addition of necessary additives. |
1. What is Grease?
Grease is a fine dispersion of an oil-insoluble thickening agent – usually soap in a fluid lubricant which is generally mineral lubricating oil. The soap is made up of fatty acid, tallow or vegetable oil saponified with alkali which can be hydrated lime, caustic soda, lithium hydroxide or aluminum hydroxide. The lubricating oil component is refined base oil-naphthenic, of medium viscosity index, or cylinder oil stock.
Structurally grease is a “water-in-oil” emulsion. Its appearance is smooth, mostly translucent, soft or hard.
Properties essential for performance of grease are structural stability, lubricating quality, low and high temperature performance (which are provided by the selected lu be oil base stock), where as properties such as water resistance, high temperature quality, resistance to break down through continuous use and ability of grease to stay in place are provided by the soap.
Additives eg. Graphite, modified clay, asphalt, oxidation and corrosion inhibitors, extreme pressure additives melybdenum disulphide etc. are used to impart specific properties as required by end application.
2. Types of Greases, applications and properties
2.1 Calcium Base : Used for simple bearings, general purpose machinery and chassis lubrication for normal temperature applications. At about 80 deg. C. water binding the oil and soap is lost so they separate and lubrication property is lost. Calcium based greases are water resistant and are low in cost.
2.2 Soda Base : Used quite generally for ball and roller bearings. Exceptionally good for sealed for life bearings. Exceptionally good for sealed for life bearings. Suitable for high temperature conditions up to 175 deg. C. Soda base greases are soluble in water. They have natural anti-corrosion and good rust protection properties. They do not separate at high rotational speed. Their cost is moderate.
2.3. Aluminum Base : Their characteristics are similar to calcium base greases – water resistance and normal temperature applications. They have exceptional stringiness and adhesive properties. Generally they are semi fluid products, clear and transparent. They are used when adhesiveness is important.
2.4. Lithium Base : Having combination of exceptionally good “lubricity”, high temperature stability, with good water resistance. These greases are selected for multipurpose industrial and automotive application. They are stable up to 175 deg.C. Where many types of machines or equipment are in operation over widely varying conditions, an inventory of several greases and grades must be maintained if only single purpose greases are used. Here lithium base multipurpose greases are attractive – offering in a single product-combination of many advantages of single use greases. Cost of lithium base is moderately high.
2.5. Barium Base : Not much in use due to high cost and time and other manufacturing factors to produce to produce soap. They have outstanding shear stability and have multipurpose applications similar to lithium base greases.
2.6. Extreme Pressure (EP) : EP agents are added to conventional greases for use where unit pressures are high or where shock loads may be encountered. EP agents are lead, chlorine, sulphur or phosphorus compounds. Molybdenum, disulphide (Moly) is widely for automotive lubricating greases.
2.7. Complex Soap: Conventional soap such as Calcium soap plus salt of low molecular weight acid such as calcium acetate provides thickener system of unique properties/characteristics eg. superior anti-wear, extreme pressure, good oxidation stability, resistance to melting at high tempera getable oil saponified with alkali which can be hydrated lime, caustic soda, lithium hydroxide or aluminum hydroxide and good water resistance. They are suitable for plain and antifriction bearings in temperature range from -20°C to 130 deg. C and for centralized systems.
They are useful for exhaust fans bearings, textile print flame dryers, glass annealing conveyor bearings, wire rolling guide bearings etc.
UNIT PROCESSES AND UNIT EQUIPMENT IN GREASE MANUFACTURING
- Pumping of raw material from storage tanks into day tanks
- Raw materials measurement by volume or weight using weighing scales, meters, tank gauges etc.
- Preparing the soap by heating and premixing fat and lube oil in kettles with counter rotating scraper
stirrer operated by motor and reduction gear. - Cooling of the prepared soap and balancing with oil to prepare grease in a cooling kettle.
- Formation of grease structure by dispersion in a milling machine under controlled moisture and temperature,
parameters. - Deareation using deareator.
- Filtering through filter.
- Filling using weigh scales/filling machines.
- Instrumentation – indicators/recorders for temperature and pressure.
- Pumps- gear and centrifugal for lube oils, vegetables oils, liquid soap and grease at various stages
of
manufacturing. - Material handling equipment like hoist, pallet trucks, and fork lifts to handle solid fats, additives, alkali,
drums etc. - Safety and fire protection devices.
- Lab equipment
- Utilities like hot oil system, cooling system, air compressor, water etc.
BRIEF OUTLINES AND MANUFACTURING PROCESSES
1. LITHIUM BASE GREASE
Reaction of lithium hydroxide with fatty acids is quite rapid, so open kettle can be used. The process involves following steps.
1.1. Heating the fatty acids to melt and mixing with 10-20% of the total lube oil as performula.
1.2. Addition of water solution of lithium hydroxide while mixing and starting of heat.
1.3. Saponification will take about 2 hours.
1.4. After reaction is complete, full heating to dehydrate the mass.
1.5. Dispersing the lube oil in soap to form grease.
1.6. Homogenizing using grease mill or homogenizer.
2. SODA BASE GREASE
Reaction of caustic soda with fatty acids is rapid, hence open kettle can be used. The process involves following steps:
2.1. Heating the fatty acid to melt and addition of part of lube oil.
2.2. Addition of caustic lye while mixing.
2.3. Heating to start reaction. Controlling the foam by anti-foam compound.
2.4. Full heating when foam subsides, to cook soap and complete the reaction.
2.5. Testing the fibrous soap and adjusting reaction.
2.6. Dehydrating the soap at about 175 deg. C. Addition of balance lube oil when soap melts.
Testing and adjusting penetration.
2.7. Cold milling in the kettle or in a grease mill to get smooth, paste like structure.
Note: Product is taken out hot at 80°C to 90°C.
3. CALCIUM BASE GREASES
As calcium hydroxide is a mild alkali, the reaction with fatty acids/vegetables oils, requires pressure cooking and high temperature for complete saponification in least time. The process involves following steps:
3.1. Heating the fat (if solid) to melt.
3.2. Addition of hydrated lime while mixing.
3.3. Addition of partial quantity of lube oil and a little water. Closing the pressure kettle.
3.4. Hearing to start reaction and cooking under pressure approx. 0.21 atm to 0.28 atm at 150°C.
3.5. Releasing pressure and discontinuing heating.
3.6. Addition of balance quantity of lube oil (retaining 5%) slowly, ensuring that it is fully absorbed
by soap.
3.7. Addition of water to form grease structure.
3.8. Testing for consistency (penetration) and adjusting as required by addition of the retained 5% oil.
