Archive | Lubricants

856

3:23 pm
January 4, 2017
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Understand Motor and Gearbox Lubrication

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Over-lubricated bearings will produce excess heat through internal fluid friction that can easily be detected with an infrared camera. Photo: Fluke Corp.

Among other factors, motor and gearbox lubrication programs require understanding and a controlled lubrication approach.

By Ken Bannister, MEch Eng (UK)CMRP, MLE, Contributing Editor

When a driven component is required to operate at a speed different than that of the attached motor (driver), a designer can choose from two basic power-takeoff speed-reduction/increaser methods. The first uses pulleys or sprockets of different diameters mounted to the motor and driven shaft, with power transmitted by a connective belt or chain. The second design connects the motor to the driven component through a gearbox, with the motor connected to the gearbox input shaft and the driven device connected to its output shaft.

When viewed in a maintenance-management-system database for lubrication purposes, belt/chain-drive motors and motor/gearbox units are rarely handled with separate PM work orders. Rather, the lubrication requirements are integrated as line items on a much broader machine PM work order. This is fine for sub-fractional and smaller horsepower motors. Larger, more expensive (and re-buildable), motors—usually 20 hp and more (there is no set rule to this)—require treatment as a separate entity from the parent machine, with their own asset numbers and PM/lubrication regimes, so as to compile work-history files. Furthermore, in the case of  motor/gearbox combinations there are two specific entities, one electro-mechanical (motor), the other purely mechanical (gearbox), that are best treated individually when assessing and managing lubrication needs.

Assuring motor and gearbox reliability is the result of good alignment practices and, more importantly, effective lubrication practices.

Bannister on Lubrication

Accompanying this article is the first of a new series of monthly lubrication podcasts with Ken Bannister. This month, he provides additional information about factors involved in lubricating motors and gearboxes.

Motor lubrication

Motors are electro-mechanical devices that turn electrical energy into mechanical energy. Motor magnets and windings are wound on and around a central shaft. This shaft is simply supported by two or more rolling-element bearings at each end of the motor frame and housing. These bearings are the only lubrication points on a motor, and are virtually always grease lubricated. With rare exception, fractional- and small-horsepower motors use sealed bearings and make no provision for external bearing lubrication. If the motor is balanced, aligned, and not overloaded, it should deliver a long life with no additional lubrication. This is not usually the case with larger motors, which are often subjected to heavier and often more variable loads, requiring larger bearings.

Depending on the motor design and manufacturer, external grease fittings usually are installed on motors rated at 5 hp and become much more prevalent on 20-hp units. When motors become more powerful and heavier, they place more load on the bearing points, therefore requiring grease replenishment on a more-frequent basis.

If a motor is to operate at peak efficiency, its bearing cavities (the available space between the balls, raceways, cage, and seals) need only be filled to 30% to 50% capacity, at any time. Because the bearings are hidden behind end plates, they are lubricated “blind” and are often subject to overfilling—especially with manual greasing. When this happens, the grease has nowhere to go except through the bearing cavity into the winding! Grease-filled windings lead to premature failure and a rapid decrease in motor energy efficiency, evident by the rise in motor’s amperage draw.

To alleviate this condition, larger motors are designed with a drain-plug or screw in the end cases that, once opened, will allow excess grease to flow through the bearing and out of the motor end case. If this is kept closed during the greasing process, excess grease will channel directly into the motor windings. If your motor has a grease fitting but no drain plug, use extreme caution not to over-lubricate, as the excess will make its way into the winding.

Over-lubricated bearings will produce excess heat through internal fluid friction that can easily be detected with an infrared camera. This can also be achieved by adding contaminated grease with a dirty grease nozzle or through cross contamination with a non-compatible grease.

Grease-gun inconsistency can be ironed out through use of a single-point auto lube (SPL) setup to deliver a small amount of lube on a continuous basis for as long as a year, depending on the size of bearing and lube reservoir.

SPL manufacturers have setup guidelines based on bearing size and altitude (atmospheric pressure is relational to constant-pressure grease flow) for initial setup, which can then be fine-tuned by monitoring amperage draw and/or bearing temperature. These signatures will be unique to each motor and will differ based on size and load.

Gearbox lubrication

Gearboxes are self-contained mechanical devices that allow power to be transmitted from an input shaft to an output shaft at different speeds through the meshing of different-sized gear sets held on each shaft. The gears and shafts are supported on bearings contained within a sealed “box” that also serves as a reservoir for the lubricating oil. Gearbox dimensions can range from palm-sized to room-sized. With few exceptions, all are oil lubricated.

Depending on the style and size, gearboxes employ a number of methods to move the lubricant over the gears and bearings, the most popular being:

• Splash lubrication. This is a common gearbox-lubrication method in which the reservoir is filled part way with lubricating oil to ensure partial coverage of all the lower mating gears. At speed, these gears use surface tension on their teeth to “pick up” lubricant and transfer to other gears and bearings through meshing and by “flinging and splashing” the lubricant in all directions within the sealed reservoir.

• Pressure lubrication. This method is frequently found on mid- to large-sized gearbox assemblies that use a gear-driven pump, typically located inside the gearbox, to work in conjunction with the “splash” method. Pressure-lubrication systems draw lubricant from the reservoir through a pickup-filter screen and pump oil at pressure through an internal piping system to bearings and gears that would be difficult to service with splash lubrication.

• Mist, or atomized, lubrication. This approach, reserved for the largest of gearboxes, uses a vane-style pump that picks up lubricant from the reservoir and “slings” it at a plate, causing it to atomize into a micro-drop mist. The mist saturates all of the mechanical components within the sealed gearbox.

In all three lubrication methods, choosing the correct oil viscosity and additive package is most important. Typical to all gearboxes is the need to ensure:

No cross-contamination of lubricants occurs during oil top-ups or change-outs. Label your gearbox with the correct oil specification.

No dirt or water contamination is allowed into the gearbox.

The drain, fill, and breather caps are always tightly in place.

The gearbox is regularly wiped clean of dirt and debris that will act as a thermal blanket and unnecessarily heat up the oil.

The gearbox is not over-filled creating churning (foaming) of the oil that can rapidly deplete the anti-foam additive, causing the oil to oxidize. This requires attaching low- and high-level markers to the gearbox sight gage.

If you have all of the above practices in check, make enquiries regarding the use of synthetic gear oils. These not only last longer but can cut your energy consumption as much as 4%. MT

Ken Bannister is co-author, with Heinz Bloch, of the recently released book Practical Lubrication for Industrial Facilities, 3rd Edition (The Fairmont Press, Lilburn, GA). As managing partner and principal consultant for EngTech Industries Inc. (Innerkip, Ontario), he specializes in the implementation of lubrication-effectiveness reviews to ISO 55001 standards, asset-management systems, and training. Contact him directly at kbannister@engtechindustries.com, or telephone 519-469-9173.


learnmore2“A Real-World Approach to Electric Motor Lubrication”

“The Inner Life of Bearings, Parts 1 and 2”

264

4:05 pm
July 11, 2016
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Use These Steps to Introduce New Lubes

Part of of the process equipment of the mechanism close-up.

The process of introducing new lubricants to your plant calls for great care, communication, and attention to details.

By Ken Bannister, MEch Eng (UK), CMRP, MLE, Contributing Editor

New lubricants are introduced into plant environments every day. There can be several reasons behind this type of move: a purchase-cost-reduction or purchase-bid program; new equipment for which the manufacturer’s specified lubricant isn’t currently stocked on site; promotion of a specialty lubricant as a way to solve a specific equipment problem; or some form of lubrication-management initiative. Unfortunately, most new lubricants are introduced in an informal, non-controlled manner with little or no communication between the reliability/maintenance, engineering and/or purchasing departments—or much consideration of the impact that the new product can, and will, have on the maintenance and operation of the physical plant.

With no structured lubrication program in place, the mixing of lubricants—greases and oils—can be endemic. This situation is a major cause of lubricant and premature bearing failure due to the cross contamination of base oils and/or additive packages. For example, a product containing acidic additives added to one containing base or alkaline additives can very quickly neutralize a lubricant’s effectiveness and protection ability, often resulting in catastrophic failure. Anyone who has toiled over implementing a lubrication-management program knows that allowing a new lubricant into a plant environment must be formalized and controlled. This process is not necessarily easy.

An essential part of any quality lubrication-management program is an initial consolidation process that reviews and documents all current lubricant products on site, where they are used, and how they are stored, handled, transferred, and delivered to minimize contamination of lubricants and bearings. This essential engineering process, performed by the lubricant manufacturer, looks for opportunities where more modern, often less expensive, products can be standardized for use across the site to replace all redundant, unsafe, and out-of-date oils and greases, and minimize the number required to operate the plant safely and effectively. In many facilities, the number of lubricants stocked and used after consolidation can be less than half the original count. For this standardization to begin, the consolidation process must determine all possible lubricant compatibility issues and propose suitable engineered lubricant change-out/flushing operating procedures.

Once a list of new lubricants is finalized, the plant must take the following steps to formalize the program:

  1. Prepare a formal approved-lubricant list for purchasing-department personnel and set up a blanket purchase-order for the approved products.
  2. Inform all affected stakeholders of the impending change(s) to an approved-lubricant list.
  3. Remove all non-approved lubricant stock from the plant.
  4. Develop a stock rotation/control procedure for all approved lubricants.
  5. Obtain up-to-date MSDS sheets for all approved lubricants and remove all non-approved MSDS sheets.
  6. Purchase dedicated (color-coded) storage and transfer equipment for all approved lubricants.
  7. Purchase labels for all approved lubricant reservoirs.
  8. Change all lubrication filters.
  9. Develop a lubricant change-out flushing procedure and systematically change out all non-approved lubricants in all machine reservoirs; re-label reservoirs.   
  10. Update lubricant-inventory-control software with lube specification, supplier, manufacturer, code numbers, min/max levels, and inventory-turn rate.
  11. Update affected preventive-maintenance (PM) job tasks in the CMMS (computerized maintenance-management system) to reflect new lubricant changes.
  12. Update any recommended changes to PM schedules in the CMMS.
  13. Update equipment manuals to reflect new lubricant changes.
  14. Update Bill of Materials (BOMs) in the CMMS.
  15. Update changes to the lubricant disposal procedure.
  16. Update any changes to reporting requirements in the CMMS.
  17. Perform staff training for change awareness, product handling and safety issues, and product disposal.
  18. Inform production.
  19. Develop a new-lubricant trial/approval procedure for any non-approved oil or grease introduced into the plant.

After a consolidation program has been implemented, only approved lubricants can be brought into the plant for regular use. This policy, however, does not exclude introduction of a new lubricant into the plant on a trial basis. Should a new lubricant trial be required, a formal request must be made to the reliability/maintenance group by completing a “Lubricant Trial Request Form.” That group, in turn, will oversee the lubricant trial.

Typical trial-request-form attributes

A good trial-request form should have enough relevant information to enable the trial to take place and collect enough relevant data from which a yes/no approval decision can be made upon the trial’s completion. The form must elicit answers to all of the W5 questions—Who, What, When, Where, Why, and How—and document the test results. (This translates to seven sections total.)

  1. Who? Contains the name, title, department, and contact details of the trial requestor, as well as details of the lubricant supplier and manufacturer name and primary contact persons. It also provides the person(s), title(s), and department performing the trial.
  2. What? Contains the trial lubricant specification data that will include its name, oil or grease, base-oil type, viscosity, VI (viscosity index) rating, additives, virgin-oil sample datasheet #/attachment, MSDS sheet, expected compatibility issues with other approved products, seals, and production raw materials.
  3. When? Contains the expected trial duration, along with commencement and completion dates.
  4. Where? Contains equipment type or specific
    equipment number of the machine on which the lubricant is to be tested.
  5. Why? Details reasons for the lubricant trial, in what way it will benefit the trial equipment and expected results, such as temperature reduction, energy reduction, life-increase expectation of lubricant and/or bearing surfaces and sustainability, and what bearing-failure reduction the trial is expected to accomplish.
  6. How? Documents the actual test procedure specifics, including lubricant disposal after the test and the conditions to be tested, i.e., amperage draw, temperature of bearings/lubricant, and lubrication-system pressure (cold and hot running).
  7. Results? Details findings data and conclusions relevant to the test, including before and after data readings, photos, infrared images, vibration readings, risk/benefit analysis, a return-on-investment statement, and a recommendation for approving or not approving the lubricant for purchase and use in the plant.

Be sure to alert plant personnel whenever a lubricant trial is being performed. Communicate this fact by placing a placard or sign on the equipment that states “Machine Under Test with New [insert name] Lubricant.” (Specifically call out the name of the lubricant). Make operators aware of such tests and notify maintenance personnel of anything unusual regarding noise, vibration, smell, and leakage during the procedure.

Before proceeding with any lubricant trial, always consult with manufacturer(s) of your approved lubricants to establish:

  • whether they have already performed a compatibility test of the trial product with your approved lubricants.
  • if, as suppliers of your approved lubricant, they have a comparable product available to test, or that you may already stock. You should also contact trial-lubricant manufacturer personnel and ask if they have conducted any compatibility tests with your approved lubricants. If no testing has taken place, you can ask if any party is willing to test compatibility on your behalf.
  • In the case of new oils, when no compatibility information is available or forthcoming—and you are unable to establish compatibility—you can perform your own testing, as follows:
  • Take samples of both lubricants and blend three mixed samples in ratios of 50:50, 90:10, and 10:90.
  • Send the three mixed samples to an oil-analysis laboratory and have them tested for filterability, sediment, and color/clarity. Also ask the lab to perform an RPVOT (rotating pressure-vessel oxidization test) to determine the new lubricant’s resistance to oxidation, and a storage-stability comparison.
  • For accurate results, tests should be performed three times and the results normalized.
  • Ask the lab to assist you in determining any cross-contamination risk.
  • Share the test results with the manufacturer of the new lubricant and ask for a change-out/flush procedure.

Note that an RPVOT can be quite expensive to perform. Thus, in the case of non-critical equipment, and if you won’t need to complete a large number of lubricant changeovers, you could forego the RPVOT and simply ask the manufacturer of a new lubricant to recommend a neutral flushing oil.

In the case of new greases, similar steps are followed. The process starts by blending mixed samples of new and existing greases in 75:25 and 25:75 ratios, and sending them to an oil-analysis lab to test for consistency, dropping point, and shear stability.

If a new-lubricant trial is deemed successful, and none of your existing approved lubricants can perform the required job, the new product can be accepted as an “approved” lubricant. The acceptance process, however, calls for the reliability/maintenance group to once again go through the appropriate steps listed above to formally integrate the new lubricant into your plant. MT

Ken Bannister is managing partner and principal consultant for EngTech Industries Inc., (Innerkip, Ontario, Canada), an asset management-consulting firm now specializing in the implementation of certifiable ISO 55001 lubrication-management programs and asset-management systems. For further details, telephone (519) 469-9173, or email kbannister@engtechindustries.com.

236

8:03 pm
July 7, 2016
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Industrial Growth Partners Acquires Des-Case Parent

Screen Shot 2016-07-07 at 2.15.47 PMIndustrial Growth Partners (IGP), a San Francisco-based private equity firm, has acquired the parent company of  lubricant-contamination-control leader Des-Case Corp. (Goodlettesville, TN).

With a 20-yr. history in the industrial sector, and $2.2 billion in capital raised since inception, IGP has extensive experience building global manufacturing businesses. According to the company, it concentrates  on leading niche manufacturers of engineered products used in critical applications, and partners with their management teams to pursue strategic initiatives focused on achieving long-term shareholder value.

Screen Shot 2016-07-07 at 2.19.40 PMFounded in 1983 when it brought the first desiccant breather to market, Des-Case now provides an array of  fluid-cleanliness products, services, and training that improve equipment reliability and extend lubricant life in industrial plants around the globe. It, in fact, has enjoyed the growth-opportunity benefits of private-equity investments since 2013, when it was acquired by Pfingsten Partners L.L.C.

Screen Shot 2016-07-07 at 2.20.35 PMIn 2014, Des-Case announced its own acquisition of the visual-oil-analysis line of ESCO Products Inc., the well-known, family-owned, Houston-based manufacturer of various  fluid-monitoring technologies and distributor of Copaltite and Dow Corning products. The acquired portfolio included ESCO’s 3-D BullsEye Viewport, oil sight glasses, indicators and level monitors.

“I am honored and excited to be a part of writing the next chapter in the Des-Case growth story alongside our valued customers, partners and investors,” noted company president and CEO Brian Gleason. “IGP has over two decades of experience investing in the industrial sector with a proven track record of building world-class global businesses. We are looking forward to the partnership.”

Other than the report that Des-Case’s management team has retained a substantial ownership stake in the company, terms of the July 6, 2016 transaction haven’t been disclosed.

For more information on Des-Case, CLICK HERE.

To learn more about Industrial Growth Partners, CLICK HERE.

58

9:00 am
July 7, 2016
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Lithium Grease

CorrLube VpCI EP grease is lithium complex grease formulated with premium quality, severely hydro treated base stock. Said to provide excellent resistance to oxidation and with high temperature stability, it is suitable for operating and lay-up conditions. The formula is designed with properties that protect against salt water, brine, H2S, HC1, and other corrosive agents. It also incorporates Vapor phase Corrosion Inhibitors (VpCI) for areas not in direct contact with the grease. The grease remains effective in extreme operating conditions such as high temperature, high pressure, and shock loading, and aids in the suspension of solid additives such as graphite, molybdenum, and disulfide. Thicker film consistency allows it to operate on worn parts.
Cortec Corp.
St. Paul, MN
cortecvci.com

388

4:50 pm
February 24, 2016
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Prevent Motor-Bearing Failures

Learn the latest on the top five causes of failed motor bearings to help stop these problems in their tracks.

By examining a failed motor bearing and understanding the clues that various types of damage often produce, you can keep these problems from plaguing your motor fleet in the future.

By examining a failed motor bearing and understanding the clues that various types of damage often produce, you can keep these problems from plaguing your motor fleet in the future.


According to the bearing experts at SKF (Gothenburg, Sweden, and Lansdale, PA) these five damage mechanisms are the most common causes of motor-bearing failures. Understanding them as you examine a failed bearing can help you prevent their recurrence.

Electrical erosion
Electric erosion (arcing) can occur when a current passes from one ring to the other through the rolling elements of a bearing. While the extent of the damage depends on the amount of energy and its duration, the result is usually the same: pitting damage to the rolling elements and raceways, rapid degradation of the lubricant, and premature bearing failure. To prevent damage from electric-current passage, an electrically insulated bearing at the non-drive end is usually installed.

Inadequate lubrication and contamination
If the lubricant film between a bearing’s rolling elements and raceways is too thin due to inadequate viscosity or contamination, metal-to-metal contact occurs. Check first whether the appropriate lubricant is being used and that re-greasing intervals and quantity are sufficient for the application. If the lubricant contains contaminants, check the seals to determine whether they should be replaced or upgraded. In some cases, depending on the application, a lubricant with a higher viscosity may be needed to increase the oil-film thickness.

Damage from vibration
Motors transported without the rotor shaft held securely in place can be subjected to vibrations within the bearing clearance that could damage these components. Similarly, if a motor is at a standstill and subjected to external vibrations over a period of time, its bearings can also be damaged. To prevent these problems, secure the bearings during transport in the following manner: Lock the shaft axially using a flat steel bent in a U-shape, while carefully preloading the ball bearing at the non-drive end. Then radially lock the bearing at the drive end with a strap. In case of prolonged periods of standstill, turn the shaft from time to time.

Damage caused by improper installation and set-up
Common mistakes in installation include using a hammer or similar tool to mount a coupling half or belt pulley onto a shaft; misalignment; imbalance; excessive belt tension; and incorrect mounting resulting in overloading. To prevent these problems, use precision instruments such as shaft-alignment tools and vibration analyzers and other appropriate tools and methods when mounting bearings.

Insufficient bearing load Bearings always need to have a minimum load to function well. If they don’t, damage will appear as smearing on the rolling elements and raceways. To prevent these problems, be sure to apply a sufficiently large external load to the bearings. This is crucial with cylindrical roller bearings, since they are typically used to accommodate heavier loads. (This, however, does not apply to preloaded bearings.)

Source
SKF is s a global supplier of bearings, seals, mechatronics, lubrication systems, and services that include technical support, maintenance and reliability services, and engineering consulting and training. For more information on motor bearings and other technologies and topics, visit skf.com.

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