Maximizing Uptime and Efficiency with Wireless Vibration Monitoring

The Need for Monitoring

According to the United States’ Department of Energy’s (DoE) Federal Energy management Program, studies show that reactive maintenance

is still the predominant maintenance strategy in the United States. This means that more than 55% of maintenance resources and activities in the average manufacturing facility are still reactive in nature. Why is this a problem? According to the DoE’s Advanced Manufacturing Office, inefficiencies in reactive maintenance processes cost the economy as much as $2.5 Trillion per year. Additionally, according to Energy Matters, a magazine published by the DoE, $750 Billion is needlessly spent every year on maintenance programs due to poor repair and maintenance practices.

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Maintain SavingsFacility Maintenance Saves Time and MoneyHow do we define maintenance? Merriam-Webster defines maintenance in the following way: “to keep in an existing state, preserve from failure or decline.” This definition implies two things. First, maintenance is a proactive, not reactive, process. Second, maintenance is a process that is undertaken to keep a machine in proper working order. So, given this definition and the staggering numbers in the previous section, why do the majority of manufacturers in the United States insist on a reactive maintenance program? Simply put, reactive maintenance is perceived to be the cheapest maintenance solution.

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Maintenance Solutions

Reactive MaintenanceReactive maintenance can be defined as a “run it till it

breaks” method of maintenance. The perceived advantages to reactive maintenance include lower cost and less maintenance staff. However, the cost savings of this maintenance method are only perceived. In reality, we are spending more money. How is this possible? First, while waiting for the machine to fail, we are actually incurring more cost because we are shortening the life of the equipment leading to having to buy replacements on a more frequent basis. Second, there is an increased cost due to unplanned downtime of equipment. Third, labor costs associated with repairs will be higher because the repairs will most likely be more extensive than if we had not allowed the equipment to run to failure. Fourth, we run the possibility of secondary equipment failing when the primary piece fails. Finally, since we are running the equipment until it fails; we will need a large inventory of replacement parts, a cost which can be reduced under more proactive maintenance strategies.

Preventative MaintenanceIn the DoE’s Federal Energy Management Program’s O&M

Best Practices Guide, preventative maintenance is defined as, “Actions performed on a time- or machine-run-based schedule that detects, precludes, or mitigates degradation of a component or system with the aim of sustaining, or extending its useful life through controlling degradation to an acceptable level.” To give an example, most of us perform preventative maintenance on our cars when we take them in for an oil change every 3,000 to 5,000 miles. While preventative maintenance is not the optimal maintenance program it does extend the life of equipment. (See Figure 1) And, although, preventative maintenance does not prevent catastrophic failures from occurring, it will decrease the number of times that they occur along with allowing the equipment will run more efficiently, both of which translate to cost savings. As a matter of fact, studies have indicated that a preventative maintenance program can have a cost savings between 12% and 18% over a reactive maintenance program.1

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Predictive MaintenancePredictive maintenance uses data collected on how a machine

is functioning to determine whether or not repairs are needed. To use the car oil change example, predictive maintenance would be comparable to the owner of the vehicle disregarding the recommended oil change frequency and instead having the oil analyzed at regular intervals to determine its actual condition to see if an oil change was needed. By doing this, the car driver may be able to extend the oil change further. According to the DoE’s Federal Energy Management Program, “a well-orchestrated predictive maintenance program will all but eliminate catastrophic failures.” With a predictive maintenance program, maintenance activities can be scheduled, replacement parts can be ordered only as required, minimizing on site inventory, and operation of equipment can be optimized, reducing energy costs and improving factory reliability. In fact, studies estimate that a predictive maintenance program can save a plant between 8% and 12% over a preventative maintenance program2 (or, 20% to 30% over a reactive maintenance program). Furthermore, surveys indicate the following savings for industrial plants that implement a well-run predictive maintenance program:

lReturn on investment: 10 timeslReduction in maintenance costs: 25% to 35%lElimination of breakdowns: 70% to 75%lReduction of downtime: 35% to 45%lIncrease in production: 20% to 25%

Reliability Centered MaintenanceRealizing that not all factory machinery is created equal,

reliability centered maintenance (RCM) combines aspects of reactive, preventative, and predictive maintenance to form the best possible maintenance solution. RCM realizes that different machines are designed and operate differently, have different rates of failure between one and another, and have different levels of importance to the operation of a facility. Also, RCM takes into account that facilities do not have unlimited financial and personnel resources. While RCM is very reliant on predictive maintenance, it takes into account that inexpensive and/or unimportant machines may just be better left to a reactive maintenance approach.

Figure 1: By Using predictive maintenace, machines can either be more efficiently maintained because parts can be serviced, or replaced, as needed. (Source: Romero et al., “Feasability Study of a Rotorcraft Health and Usage Monitoring System (HUMS),” 1996)

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Vibration Monitoring as Part of Your Maintenance Strategy Vibration is defined as “a periodic motion of the particles of an elastic body or medium in alternately opposite directions from the position of equilibrium when that equilibrium has been disturbed.” Put another way, vibration is simply a back-and-forth movement. Many parts of industrial machinery vibrate and each machine has its own vibration pattern.

What causes a machine to vibrate? There are three main factors that cause machine vibration. These factors include repeating forces, looseness of machine parts, and resonance. Repeating forces act on a machine in much the same way that waves slapping the sides of a moored boat may cause the boat to rock and can indicate an imbalanced, misaligned, worn, and/or improperly driven machine. Looseness is caused by loose parts or excessive clearances of machine parts. Resonance is a repeating force that matches the rhythm of the natural back-and-forth movement of the machine and can cause rapid and catastrophic damage to a machine.

Using vibration monitoring systems we can detect how much a machine is vibrating, and, if the machine is vibrating outside its normal parameters, it could indicate a potential problem. Vibration monitoring can be used to discover a wide range of problems including:

lImbalancelMechanical looseness/weaknesslEccentric rotorslRotor rublMisalignmentlSleeve-bearing problemslResonance problemslRolling element bearing problemslFlow-induced vibration problemslGear problemslElectrical problemslBelt drive problems

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The Importance of Monitoring Machine Vibrations

Why is it important to monitor machine vibrations? The simple answer is vibration monitoring allows for the monitoring of the “health” of a machine. Since not all machine failures occur at predicted times in a machine’s life cyle, if a machine’s health can be monitored, it is possible to detect problems that are starting to develop and therefore fix them before they become more severe. (See Figure 2) Early detection and maintenance is important because it can lessen the likelihood of more severe and costly machine damage, help save on power consumption, reduce machine unavailability, help prevent delayed shipments, help prevent the accumulation of unfinished goods, help prevent unnecessary preventative maintenance, help reduce quality issues, help reduce occupational hazards, and help maintain company image.

For example, in a case study cited in the DoE’s Federal Energy Management Program’s O&M Best Practices Guide, vibration monitoring saved one company over $6,300 for a single machine. Through vibration monitoring, improperly sized shaft bearings were discovered on both the pump and motor ends of a 200-hp motor/pump combination. Repair costs were less than $2,700, while continued operation would have led to a machine breakdown and replacement costs over $10,000.

Figure 2: Over 80% of machine failures are random (see column titles), indicating that predictive or reliability centered maintenance with some form of machine monitoring is preferred over preventative maintenance. (Source: Wheeler, “Align Facilities Engineering Objectives with Business Goals to Improve Results and Eliminate Wasted Time and Money,” 2007)

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4Jim Ralston, “Improving Plant Production with Wireless Condition Monitoring,” 26 March 2012 <http://www.automation.com/resources-tools/ articles-white-papers/condition-monitoring/improving-plant-production-with-wireless-condition-monitoring>

Monitoring MethodsTraditionally machine vibration monitoring is performed in

two ways. Machines can either be periodically monitored by utilizing a temporarily mounted sensor and a portable analyzer machine. Or, machines can be continuously monitored by permanently mounting sensors and wiring them into a high end diagnostic system in the plant. (See Figure 3) The advantage of a portable system is that it can cost less to procure and install (since there is no permanent wiring required, however, if a facility decides to hire an outside firm, this option can even be costly, running between $600 and $1,200 per day3) while still providing some level of predictive monitoring. The disadvantage of a portable system is that machine values don’t follow a schedule and there is a very real possibility that a machine can develop problems or even fail between the periodic assessments. Permanently mounted sensor systems attempt to address this issue but they do so at a very high cost. Acquiring and installing a permanent system can run into the hundreds of thousands of dollars when you factor in the cost of the sensors, diagnostic machine and software, and the installation and maintenance of long wire runs that are necessary to both power the sensors and collect the vibration data. These costs can dramatically affect the return on investment (ROI) of continuous machine vibration monitoring for predictive maintenance and put such systems beyond the financial reach of most companies. Utilizing wireless communications for vibration monitoring can help.

Figure 3: Smart Diagnostics wireless sensor compared with a wired sensor.

3United States, Department of Energy, “Operations and Maintenance Best Practices: A Guide to Achieving Operational Efficiency.”

5United States, Department of Energy, “Industrial Wireless Technology for the 21st Century.” Dec 2002, 27 March 2012 < www1.eere.energy.gov/industry/sensors.../wireless_technology.pdf>

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Wireless vs. Wired MonitoringPermanent machine monitoring has traditionally been

performed using wired sensors. With costs for wiring vibration sensors ranging from $10 to $40 per foot, wire installation costs are a driving factor that limits the affordability of vibration monitoring. Wireless sensors address this cost issue. Additionally, wireless sensors offer to simplify sensor installation, reduce maintenance associated with wiring faults, permit new sensor locations that would not have otherwise been accessible with wired sensors, and offer greater flexibility in that sensors can be easily installed, or removed, as required.

A case study at a coal power plant illustrates the advantages of wireless versus wired monitoring. The plant was looking to monitor their cooling fans at the base of their cooling towers. The monitoring system was easy to install, however the towers lacked infrastructure to connect them to the plant’s Ethernet network. Fiber optic cable could be pulled through the towers, however it was estimated that it would cost the plant $100,000 (see sidebar) and take over six months to install. Instead the plant decided to investigate using wireless and found out that it would only cost a small fraction for the cable and could be installed in three weeks.4

In summary, wireless sensors have the promise to make vibration monitoring practical for most companies.

However, with all of the upsides to wireless monitoring, it does not come without its drawbacks. To begin with, battery life has traditionally presented usability problems because battery replacement is an additional maintenance activity that can offset the savings provided by wireless sensors. Energy harvesters have been proposed as a solution to this problem; however, they can be expensive, with a successful harvester often costing up to $1,000. Furthermore, traditionally, wireless sensors have been limited by the usable bandwidth available for transmitting vibration data. Either a limited amount of data could be sent over a narrow bandwidth or more data could be sent over a wider bandwidth but battery life would greatly suffer.

Solving this power versus bandwidth challenge in order to deliver viable wireless vibration monitoring has been a key focus of KCF Technologies’ research efforts over the past 10 years.

According to the DoE, wireless sensors cost between $500 and $5,000 installed.5 That’s between half of a percent and five percent of the cable installation estimate in the coal power plant case study.

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KCF’s “Smart” SolutionWelcome Smart Diagnostics, KCF Technologies’ wireless

machine vibration monitoring solution. Smart Diagnostics provides all the cost advantages of wireless vibration monitoring plus it addresses the battery life versus bandwidth tradeoff. As a result KCF has made automated condition monitoring affordable for far more industrial equipment owners than has previously been possible.

Widespread adoption of harvester-powered industrial wireless sensors represents an enormous opportunity for cost savings and process efficiency improvements. Industrial wireless sensors promise to be a major contributor to U.S. and global economic health in the coming decades. However, installations have consistently lagged forecast predictions for two reasons: 1) lack of turn-key solutions that are easy-to-install and use; and 2) power. The first challenge is being addressed by some companies and the installed base of wireless sensors is rapidly increasing, but solutions are still needed which can transmit a full spectrum of vibration data at low power. This power challenge can be solved either with very low-power sensors which are limited to measuring and transmitting simple state variables (temperature, pressure, etc.), or with energy harvesting solutions that generate sufficient power to transmit vibration spectrum data.

While research abounds in projects aimed at creating low power sensors and energy harvesting technologies, no company has yet offered a working, cost-effective, industrial-grade solution. Through more than a decade of technology research and development in Department of Defense (DoD) and industrial applications, KCF Technologies has developed the Smart Diagnostics product suite to address these challenges.

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The Smart Diagnostics SuiteKCF Smart Diagnostics Solution Suite is a family of products,

that includes energy harvesters, sensors, and software, that companies use to implement predictive maintenance processes as part of a balanced reliability centered maintenance system. Industrial strength in design, yet affordable, the Smart Diagnostics systems open up the opportunity to implement sophisticated condition based monitoring on a broad array of equipment and brings the technology into financial reach of small and medium sized organizations.

At the core of the Smart Diagnostics solution family is the Smart Diagnostics Vibration Monitoring System (VMS) which consists of powerful, easy to use software, and low power wireless vibration sensors that enable users to visualize the operating state of vibrating equipment in order to predict when to perform maintenance. The vibration sensor node is small (less than 70 grams) and delivers high fidelity vibration data (3 kHz vibration bandwidth). The VMS software provides a simple interface to configure frequency monitoring bands with “warning” and “alarm” thresholds. The system generates alarms when observed vibration exceeds these thresholds. In addition VMS provides easy to read charts that show both the trending over time of peak vibration in the monitoring bands as well as full vibration spectrum of each sensor sample.

In order to ensure high bandwidth, high reliability wireless communication at the lowest possible energy budget KCF’s Smart Diagnostics sensors utilize a proprietary super-efficient wireless protocol. Compared to traditional protocols, KCF’s protocol is optimized to use short power-on times, short on air times, and ultra-low power acknowledgments which minimize the time that the sensor node is on while still transmitting full dynamic vibration spectrum over the air on a frequent basis using only using only the power available from energy harvesters. (See Figure 4) The protocol operates in the 2.4 GHz Industrial, Scientific, and Medical (ISM) frequency band for data bandwidth, and comfortably coexists with other wireless networks operating in the same band (i.e. WiFi) due to its small packet size and very low overheads. The VMS network consists of wireless sensor nodes, wireless receivers and collection server nodes that connect seamlessly into a company’s network backbone. These characteristics make this protocol ideal for implementing wireless sensors in a plant environment.

Figure 4: Energy consumed per communication comparison between Smart Diagnostics sensor and reciever and standard sensor and reciever. (Source: Loverich,“Energy Harvester Power Wireless Sensors for Extreme Temperature,” 2011)

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Energy HarvestersBatteries are included with the sensors, but are not required.

While the Smart Diagnostics wireless sensors will operate effectively for eight or more years* (compared to approximately four to five years with other sensors5) using an on-board 3.6V AA battery, they will operate virtually indefinitely using energy that is scavenged from the environment. To harness energy from the environment KCF complements its wireless sensors with a family of Smart Diagnostics Energy Harvesters designed to scavenge energy from:

lHeat: works at low temperature gradient (10-15° F) easily power the Smart Diagnostics sensors from the temperature difference between the open air and the surface of a common industrial motor,

lLight: works indoors or outdoors on the cloudiest of days (<500 Lux) making it great for powering sensors on equipment on roof tops and in other outdoor or higher light indoor environments, and

lVibration: works at low vibration levels (200-1600 Hz) and is less sensitive to variation in vibration making it ideal for harvesting power from industrial compressors, fans, and gear boxes.

The harvesters are all designed to deliver near continuous power to wireless sensors or other low power devices. They can be mixed and matched so you choose the right harvester for the environment. The harvesters leverage KCFs patent pending technology to ensure rapid charge up for initial sensor readings and long energy storage of excess harvested energy to ensure sensor operation for times when environmental energy is not available. Like all products in the Smart Diagnostics suite the harvesters are engineered to be very robust -- suitable out-of-the-box for installation in harsh industrial settings.

*With an approximately one measurement per hour duty cycle.

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So, there you have it…

Strategic advantage is derived from optimizing and managing the risk of catastrophic machine failure better than your competitor

does. KCF Technologies’ Smart Diagnostics vibration monitoring sytstem helps manufacturers do that by bringing high quality machine prognostics within their reach thus allowing them to maximize the productive utilization of their equipment while reducing both the risk of failure and unnecessary scheduled downtime and maintenance costs.

The Smart Diagnostics Vibration Monitoring System’s Deluxe Starter Kit

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KCF Technologies336 South Fraser StreetState College, PA 16801814-867-4097www.kcftech.com

sales@kcftech.com

Published May 2012Copyright 2012 KCF Technolgies