Types of Industrial Lubricants Explained: Grease, Oils, Synthetic vs Mineral

Industrial lubricants are essential for the maintenance and protection of moving parts in machinery.

If you use the right lubricants, you can reduce friction and wear. It can also help you remove heat, seal out contaminants, and keep the parts moving smoothly.

When it comes to lubricants, you will notice that there are quite a few options available.

You should be careful to pick the best one out of them as per your application.

Read on and let’s explore how you can do it.

Greases

Greases are thick, jelly-like lubricants made by dispersing a thickening agent in lubricating oil. The oil provides the main lubricating properties, while the thickener gives grease its semi-solid consistency for sticking to surfaces. Greases stay in place longer than oil.

Some common thickeners used in grease include:

• Soap thickeners - Most widely used due to good versatility. Made from fatty acids combined with metal hydroxides. Lithium, aluminum, calcium, and sodium soaps are common.
• Clay thickeners - Providing stability at high and low temperatures. Bentonite and kaolin clays are often used.
• Polyurea thickeners - Known for oxidative stability and water resistance. reaction of amines with isocyanates forms these polymers.

Greases have the advantages of sealing out contaminants like dirt and moisture as well as resisting leakage from bearings and joints. They also require less frequent application compared to oils.

Disadvantages include limited heat transfer capability and a tendency to oxidize at high temperatures over time.

Common grease consistencies classified by NLGI grades:

000: Fluid like oil, used where frequent lubrication is difficult 0: Soft, like bearing and motor greases 1: Light viscosity, for ball joints and chassis parts 2: Moderate viscosity, all-purpose automotive grease 3: Thick, tacky, suited for open gears and slides

Oils

Lubricating oils make up a large share of industrial lubricants, using base oil combined with packages of additives.

They spread readily to coat surfaces with a film for reducing friction and wear. Ease of pumping and circulating gives oils better cooling abilities than greases.

Industrial oils come in varieties ranging from lightweight fluids to thick gear lubricants, with specifications meeting international (ISO), regional, or proprietary standards. Categories include:

• Hydraulic fluids: Transmit power in hydraulic equipment. Balance viscosity, compressibility, cleanliness, and material compatibility.
• Gear oils: Protect enclosed gearboxes under heavy load stress. Withstand high pressures and temperatures while reducing wear.
• Compressor oils: Lubricate rotary and reciprocating air compressors. Resist oxidation while sealing clearance spaces.
• Turbine oils: Designed for steam, gas, and hydro turbines. Provide thermal and oxidation stability at temperatures exceeding 200°C.
• Circulating oils: Lubricate bearings and gears in circulation systems. Resist formation of deposits while promoting cooling.
• Refrigeration oils: Specifically for ammonia and halocarbon refrigeration compressors. Balance miscibility, viscosity, stability and material compatibility.
• Slideway oils: Accurately guide machine tool parts like lathes. Stay viscous to resist wash off.
• Heat transfer oils: Transfer heat indirectly in high temperature fluid systems. Withstand thermal stress avoiding breakdowns.
• Textile oils: Condition fibers, minimize breaks and control friction on textile machinery.
• Process and rust oils: General oils for nonspecialized lubrication, corrosion prevention, and process requirements.

Synthetic vs Mineral Oil Base Stocks

The base oil makes up the main component of lubricants before additives are blended in. Industrial lubricants use either mineral oils, synthetics, or semi-synthetic blends as bases.

Mineral Oils

Derived from crude oil refinery processes, mineral oils provide good versatility and compatibility. Types include:

• Paraffinic mineral oil: Composed of n-paraffins. Offer excellent stability but poor cold temperature properties. Used for turbines, hydraulics, gears.
• Naphthenic mineral oil: Contain cycloparaffins. Provide low viscosity indices but good low temperature fluidity. Used in turbine oils and process oils.
• Aromatic mineral oil: Made of alkylated aromatics. Poor oxidation stability but good solubility properties. Used as process oils.

Synthetic Oils

Wholly synthesized from select chemicals, synthetics demonstrate improved performance capabilities:

• PAOs (Polyalphaolefins): Made by oligomerizing linear alphaolefins. Provide exceptional stability, useful temperature range and viscosity index. Common as compressor, gear, bearing and hydraulic lubricants.
• Esters: reaction products of acids and alcohols. Resist oxidation and hydrolysis while providing solvency. Best as turbine oils, refrigerants, and for extreme conditions.
• PAGs (Polyalkylene glycols): Polymerization of alkylene oxides. Excellent low and high temperature properties. Main use is polyurea greases due to water solubility.

Semi-Synthetic Oils These blend the desirable properties of mineral and synthetic oils. Adding a synthetic component can enhance mineral oil performance. Conventional gear oils, for example, may be enhanced with PAO or ester to achieve greater EP performance. Costs are lower compared with 100% synthetics.

Final Words

With many machineries lubricant options, from low viscosity hydraulic fluids to adhesive open gear greases, the most suitable lubricant depends on your operating conditions and application requirements. OEM specifications should be followed closely. Within specifications, semi-synthetic and full synthetics can offer performance advantages over mineral oils in terms of stability at temperature extremes, extended oil life, reduced deposit formation, and efficiency. Consulting an experienced lubricant specialist is invaluable for matching the optimal lubrication product to your needs. Proper oil analysis will then validate performance over time.