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