Gary Patrick, senior consulting engineer at SKF, talks about bearings, condition monitoring, and devices provided by the company at SMRP 2016.
Modern rolling contact bearings, when installed and lubricated properly, can outlast the machines in which they function. In practice, though, less than 10% of all rolling-element bearings reach their full design life. As for the others, 30% of premature failures can be attributed to incorrect installation or damage done during (or prior to) installation. Continue Reading →
The company’s line of L-Jaw couplings includes a range of bore sizes and aluminum and stainless-steel hubs. The line is part-for-part interchangeable with industry-standard designs. An interchange guide is available. A wide range of sizes is offered with torque ratings to 6,228 in. lb. and bore sizes to 2 7/8-in. dia. Couplings can accommodate as much as 1 in. of angular misalignment and have an operating temperature range of –60 to 250 F.
TB Wood’s Inc.
Power producers are encountering many changes to their business model and remote monitoring — along with predictive analytics — is an attractive value proposition to end users. GE’s Predix platform offers SmartSignal, a software system that models historian plant data and constructs anomaly data to measure current conditions at a power plant. The modeling is called Variable Similarity-Based Modeling (VBM) technology and can be teamed up with GE’s Industrial Performance and Reliability Center (IPRC) to provide a comprehensive reliability solution.
This white paper introduces key concepts from the SmartSignal software and examines three power plant case studies.
Maintenance Technology’s IIoT page | Find out more about edge computing and other proactive maintenance approaches.
Learn the latest on the top five causes of failed motor bearings to help stop these problems in their tracks.
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.
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.)
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.
HD Enveloping is a high-definition vibration enveloping technique for detection of early-stage gear and bearing faults. A complement to traditional vibration analysis, the method detects, at a very early stage, machine problems that are generally difficult to find in good time with conventional non-enveloping techniques. Significantly extending the planning horizon for predictive maintenance, the method is said to be a boost to maintenance efficiency. The technique can be used with existing vibration transducer installations and integrates into existing industrial infrastructures while monitoring applications in the 15,000 to 20,000 rpm range.
The unit of measurement is HD Real Peak, a scalar value expressed in decibels. Representing the true amplitude levels found in the envelope signal, HD Real Peak is the primary value to use for determining the severity of a given damage. It is also used for triggering alarms. Using order tracking and symptom enhancement, applying FFT on the signal is very useful to determine the source of the signal. Spectrums and time signals provide a snapshot of machine condition to give the maintenance department a heads-up on potential problems. Straightforward setup uses a set of predefined filters, each designed to detect damages or anomalies in different stages of development.
Did you know that some simple cooling tower maintenance could help your facility save up to 15% on its electricity costs? Routine preventive maintenance also can help conserve water and extend the operating life of your cooling equipment.
Over time, the leaving-water temperature of a neglected cooling tower will rise, as will the energy costs to operate the equipment. (For every 2-degree F increase in temperature, those energy costs can increase by up to 6%.) A well-maintained cooling tower, however, will continue to function at its original optimum efficiency, keeping energy costs low.
To get the most from your cooling equipment, heed these maintenance tips:
#1. Check overall cooling and listen for any uncommon noises in the system to establish a baseline of possible issues.
#2. Before beginning any hands-on work, be sure to follow proper lock-out/tag-out procedures and disconnect motor switches to protect your safety and that of other personnel.
#3. To keep the system free of potentially problematic materials, inspect and clean debris from strainers.
#4. To avoid a build up of scale and increase capacity, inspect the water-distribution system and check for dry areas over the fill-coil section. If the surface isn’t fully wetted, check the nozzles for cracks and clogs.
#5. To ensure desired water filtration and prevent dirt from collecting in the system, flush dirt and debris from the cold-water basin through the tower drain or sump strainer. Basin-sweeper piping installed in addition to a filtration system will function as automatic maintenance.
#6. To conserve water and reduce air entrainment, be sure the make-up water supply is at the appropriate, pre-determined level.
#7. To prevent accumulation of solids in recirculating water, adjust the bleed rate according to your local water-quality and evaporation-rate regulations.
#8. To ensure optimal performance on a belt-driven system, fix any tension problems with the belt.
#9. To assure reliable service in a gear-driven system, routinely check for and maintain, correct oil level, oil quality and shaft alignment, per the manufacturer’s’ recommendations.
#10. Lubricate fan shaft bearings every three months, at a minimum. Consider installing automatic bearing greasers to eliminate monthly bearing maintenance.
When all is said and done
Keep in mind that maintenance frequencies will vary depending on the condition of the circulating water and the environment in which the cooling equipment runs. Among other things, it’s also important to remember that storing critical parts in inventory is a good strategy for reducing unplanned downtime. Consult your local equipment supplier regarding additional strategies.
The bottom line is this: As with other systems in a plant, good maintenance habits will go a long way in preventing failures and extending the life of your cooling equipment.
Information in this article was provided by Baltimore Aircoil Company, a leader in the design and manufacture of evaporative-cooling and heat-transfer equipment.
SKF has introduced an axial excluder seal that offers a high-performance alternative to conventional rubber seals for protecting the main shaft bearings on wind turbines.
According to the manufacturer, as an advanced first line of defense against any debris or contaminants the wind carries, this new seal can help operators reduce the risks of bearing failures and associated costs of downtime, repair and lost productivity.
Unlike conventional rubber seals that can be prone to excessive wear and subsequent failure, this axial excluder design (designated HRC1) is made of a proprietary SKF polyurethane material that exhibits excellent resistance to wear, abrasion, UV radiation and ozone.
Key features include a robust sealing lip to help reduce bending and minimize contact area, friction and wear; optimized flexibility and engineering geometry allowing axial displacement of + 2 mm; and integrated grooves to keep the sealing edge properly lubricated. The product also incorporates a stainless steel clamping band with a fast-lock mechanism to facilitate easy up-tower installation and fixation on the shaft in new installations, as well as retrofits.
SKF notes that early field trials have confirmed the HRC1 seal’s performance levels and durability. Seals were installed on 40 separate 2.5 MW turbines operated continuously under real-world conditions. After three months, an initial inspection revealed only normally expected run-in wear, with no dramatic changes six months later.
HRC1 axial displacement seals are available in standard solid and split versions for shaft sizes from 1m to 3m. Custom solutions can be developed.