Lubricant SelectionSabita Mishra

Tribological System

Before the proper lubricant can be selected, the tribological system must be identified. This system includes the following:Type of motion SpeedTemperatures Load Operating environment.

Lubrication Selection Criteria –

Service temperature rangeSpeed factor (ndm)Hydrodynamic lubricationElastohydrodynamic lubricationExtreme pressureEmergency lubricationFretting

Lubrication Selection Criteria – Other Specialized Reasons

Design lifeLubrication equipmentAcceptable relubrication intervalsCostSpecial certifications such as NSF registrationBiodegradability

Reason for Use of Specialized Materials

• Temperature extremes (too much heat, too much cold)

• Pressure extremes (too much load, inadequate surface area, inadequate surface speed)

• Environmental extremes (moisture, particulate, corrosive gases, high vacuum)

• Process issues (incompatibility with process chemicals, risk of process contamination)

• Installation and design issues (limited access, dangerous access)

Reasons for Lubricant Brand Change

Consolidation (Reducing the total number of brands or products)

Unsatisfactory historic performance (Current lubricant fails to deliver performance needs relating to reliability, energy, economy etc.

Reduce lubricant costCurrent product has been discontinued by the supplierCompany wide lubricant supplier change (sometimes

due to a recent merger/acquisition event)

Synthetic Fluid Categorization

Advantages of Synthetics Outperforms mineral oil at very high and low operating

temperatures Improved energy efficiency due to better low temperature

properties Higher oil film strength with some synthetics Extended warranties by some equipment manufacturers Lower engine hydrocarbon emissions Extended drain intervals in some applications Biodegradability with some synthetics Natural detergency Higher viscosity index Fire resistant (Phosphate esters)

When to Use Synthetics

When equipment performance demands exceeds capabilities of mineral based fluid

When synthetic properties can become problem solvers

When life cycle cost savings can be releasedWhen safety and environmental issues can

be enhanced

Lubricant Selection Chart

Lubricant Changeover Options

Lubricant Changeover Problems and Risks

Incompatibility with previous lubricant Incompatibility with internal sediment, sludge or varnish Incompatible with machine internal surfaces Incompatible with machine operating conditions and

exposures The new lubricant has performance weaknesses or

drawbacks The equipment is old with high machine duty and

criticality Unknown additive chemistry Complex lubricant formulations

Lubricant Survey Overview Lubricant technical selection practices Lubricant application practices Oil analysis program practices Condition control practices Lubrication practices standardization (SOPs) Long term lubricant stability Lubrication survey and lubricant vendor selection Consolidate lubricants Set lubrication preventive maintenance (PM) frequency Root cause mapping and correction Program effectiveness reporting Program management and personal development

Lubricant Survey Overview (Cont’d)

Eliminate unnecessary oil changes Eliminate premature aging of lubricants Verifying, defining lubrication practices Verifying, defining re-lubrication activities like volumes,

frequencies, route sequences, machine upgrades etc. Purchase necessary lubrication equipment and tools Perform financial analysis review and establish a cost basis Reduce the number of lubricants in use and thereby reduce the

chances for mis-application and cross contamination Contamination control practices Upgrading knowledge level Develop a lubrication manual

Storage and Handling Survey Overview

Lubricant delivery, storage and handling practices should be followed

Wasteful practices of products, duplication and excess inventory should be eliminated

Storage room temperature extremes should be avoided Fluctuating temperatures should be avoided Containers should not be stored in a humid environment First in first out (FIFO) system should be maintained such that

stocks are rotated properly All new drums should be filtered to an appropriate level. Use a

ß3=200 filters for lubricants below 150 cSt @ 40⁰C. Use ß6=100 filters for lubricants above 150 cSt @ 40⁰C

All drums and containers should be labeled and color coded and filtered drums should be labeled as such with the date of filtration.

Storage and Handling Survey Overview

Filtered drums should be fit with an appropriate air filter to offer air flow a path of least resistance allowing moisture and solid particulate to be captured prior to entering the drum.

When new oil is transferred to the top-up container, it should be transferred through a filter.

Oils should be stored in fluid storage racks Fluid storage racks should have oil and air filtration Proper dispensing containers should be used and stored in an explosion

proof cabinet Drums should be stored horizontally and covered to keep excess

moisture and dirt from settling on them. The openings (bungs) should be at 3 and 9 o’clock positions to minimize the amount of breathing in the drums

Drums should be fitted with dispensing taps with covers