Archive | Motors & Drives

24

7:32 pm
June 25, 2017
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Stepper Motion-Control Products

1706mtprod09pA line of motion-control stepper products includes controllers, stepper motors, and integrated controller/drive, and integrated drive/stepper motor, and an integrated controller/drive/stepper motor. Produced in conjunction with Advanced Micro Controls Inc., the products, when combined with an IDEC FC6A PLC and its embedded motion-control macro instructions, allow users to implement single- and multi-axis motion control in a wide range of applications. Macro instructions embedded in the PLC WindLDR programming software can be configured with drag-and-drop commands to perform control of as many as12 axes.
IDEC Corp.
Sunnyvale, CA
idec.com

13

7:30 pm
June 25, 2017
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Gear Motors

1706mtprod08pA line of gear motors based on the company’s Sigma-7 servo motors provide precise servo motion to a wider variety of automation applications, especially to uses that require high torque at low output speeds. A new set of gearheads is designed to pair precisely with every servo motor in the line, creating solutions from 50 W to 15 kW. Five gear ratios are available, from 3/1 to 50/1.
Yaskawa America Inc.
Waukegan, IL
yaskawa.com

365

6:39 pm
May 15, 2017
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Understand Motor/System Baselines

Want to get the most from your electric motors? Think of St. Louis-based EASA (Electrical Apparatus Service Association,  easa.com) as a treasure trove of practical information and its members as a “go to” source for help with specific applications. Consider this insight on motor/system baselines.

— Jane Alexander, Managing Editor

According to EASA’s technical experts, changes in motor/system vibration readings provide the best early warning of developing problems in a motor or system component. Other parameters to monitor may include operating temperature of critical components, mechanical tolerances, and overall system performance, including outputs such as flow rate, tonnage, and volume.

Motor-specific baselines incorporate records of electrical, mechanical, and vibration tests performed when units are placed in operation or before they’re put in storage. Ideally, baselines would be obtained for all new, repaired, and in situ motors, but this may not be practical for some applications. These baselines typically include some or all of the following:

randmLoad current, speed, and terminal voltage

Changes in these parameters usually indicate that a vital system component is damaged or about to fail. Other electrical tests may include insulation resistance, lead-to-lead resistance at a known temperature, no-load current, no-load voltage, and starting characteristics.

QUICK TIP: Some changes in the current and speed may be normal, depending on the type of load.

Motor current signature analysis (MCSA)

This test diagnoses squirrel cage rotor problems, e.g., broken bars or an uneven air gap. It’s more accurate if a baseline is established early in the motor’s life.

Mechanical tests

These normally consist of measuring shaft runout (TIR) and checking for a soft foot.

Vibration

Although overall vibration readings can be used as baseline data, Fast Fourier Transform (FFT) spectra in all three planes at each bearing housing are preferred (see “Vibration Analysis” on page 22). Shaft proximity probes can be used to determine sleeve bearing motor baselines.

Infrared thermography

This tool can detect changes in the operating temperature of critical motor components, especially bearings.

New-motor baselines

Comparing factory terminal winding resistance and no-load amps with data taken under load can be useful when monitoring the condition of a new motor or troubleshooting system problems. Factory baselines are often available from the manufacturer or its website. The accuracy of factory data depends on how it was obtained, but it’s usually sufficient for field use.

Baseline data for a newly installed motor could reveal an error, e.g., misconnection for an incorrect voltage, and prevent a premature motor failure. Rather than simply “bumping” a motor for rotation before coupling it to the load, operate it long enough to measure the line current for all three phases, as well as the voltage and vibration levels.

QUICK TIP: Comparing the baselines of a failed motor and its replacement could reveal application- or process-related weaknesses in the system.

Repaired motor baselines

Service centers usually provide no-load and/or full-load (when stipulated) test data for repaired motors, including voltage, current, and vibration spectra. Comparing these results with historical baselines and those obtained on site when the motor is returned to service may confirm the quality of the repair or possibly reveal underlying system problems. For example, increased vibration levels in on-site tests might indicate a deteriorating motor base or a problem with the driven equipment rather than a balancing issue with the motor.

With newly repaired motors that have been in operation for many years, baseline comparisons are invaluable in root-cause failure analysis and may even expose consequential damage from certain kinds of failures, e.g., a broken shaft. To correctly identify cause and effect and prevent recurrences, always investigate equipment failure at the system level. MT

For details on using motor/system baselines, as well as expert advice on a wide range of other motor-related issues, download Getting the Most from Your Electric Motors, or contact a local EASA service center.

344

4:47 pm
May 15, 2017
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Beware Self-Inflicted Reliability Problems

modern manufacturing industry and mechanization concept, abstrac

Think of this expert advice as a reality check for your operations and take action accordingly.

By Jane Alexander, Managing Editor

The root cause of poor reliability can come from many sources, including aging plant assets, poor design decisions, even disregard for reliability by those who built and/or installed the equipment. Then, there are the many other reasons outside of your control that could be contributing to the reliability problems your site is experiencing today. While any reliability-improvement initiative will require that all of those issues be addressed, according to Jason Tranter of Mobius Institute (mobiusinstitute.com, Bainbridge Island, WA), operations must first deal with those of the “self-inflicted” variety.

Don’t think you have self-inflicted reliability problems? Tranter begs to differ. It’s a bitter pill to swallow, but yes, you do,” he said. “That’s good news, though, since it is much easier to deal with the self-inflicted root causes than the inherent reliability problems you adopted.”

What does Tranter mean by self-inflicted? To determine why equipment fails prematurely and/or why you experience slowdowns, safety incidences, or quality problems, he explained that personnel could go through a detailed reliability-centered maintenance (RCM) analysis process, or perform root-cause failure analysis (RCFA) after each failure occurs. “Better yet”, he said, “they can learn from the experience gained at thousands of plants around the world and consider some of the most common root causes of equipment failure.”

Focusing on rotating equipment, Tranter outlined those types of problems as follows, starting with the most obvious and working backward to their root causes.

#3. Cause of Reliability Problems: Imperfect operating and maintenance practices

Most of the equipment in a plant or facility, i.e. motors, pumps, fans, compressors, and turbines, is designed to run for many, many years without unplanned downtime. While those types of assets may incorporate some components that wear out, many items, such as bearings and gears, are designed to provide years of trouble-free operation. This, however, assumes that all of the parts were installed correctly, the components are precision aligned, the bearings and gears are correctly lubricated, all fasteners are tightened to the correct torque, there is no resonance, belts are tightened to the correct tension, and the rotors are precision balanced.

It also assumes that the equipment is operated as designed. Pumps, for example, should be operated at their best efficiency points (BEPs). “If you are unsure these types of situations are occurring,” Tranter cautioned, “then they almost certainly are.” He pointed to several areas where seemingly minor issues could be causing serious problems:

1705fvibration2

Just 5/60th of a degree of angular misalignment can cut bearing life in half. (Reference: Harris, Tedric A., A Rolling Bearing Analysis, John Wiley & Sons, New York, 1984.)

Shaft alignment. When two shafts are “collinear” (no angle or offset between their centerlines) it reduces stress on the bearings, couplings, shafts, and the rest of the machine components. Research has revealed that just 5/60th of a degree of angular misalignment can cut bearing life in half (see Fig. 1).

If you use laser alignment with appropriate tolerances, and you remove soft foot, then this will not be a source of poor reliability. By the way, just because your vibration analyst does not detect misalignment does not mean that your machines are precision aligned.

The life of a bearing is inversely proportional to the cube of the load.

The life of a bearing is inversely proportional to the cube of the load.

Balancing. When you balance to ISO 1940 grade G 1.0, the cyclical forces on the bearings, shaft, and structure are minimized and you gain reliability. If you do not have a balancing standard, then unbalance will be a root cause of failure. If you wait until the unbalance generates “high” vibration, then you will have reduced the life of the equipment and supporting structure. That’s because the life of a bearing is inversely proportional to the cube of the load (see Fig. 2). Tranter noted that, while this calculation sounds very complicated, it basically means that if you double the load, a bearing’s life will be reduced to an eighth (23).

Tiny 3-µm particles cause more damage than 40-µm and 10-µm particles (Reference: A Study by Dr. P. B. McPherson)

Tiny 3-µm particles cause more damage than 40-µm and 10-µm particles (Reference: A Study by Dr. P. B. McPherson)

Lubrication. When you correctly lubricate bearings and gears, whether with grease or oil, and that lubricant is free of contaminants, you will achieve maximum life. But if bearings are not adequately greased, their life will be reduced. If the oil is contaminated, the viscosity is incorrect, or additives are depleted, then the life of gears and bearings will be greatly reduced.

Research was performed to determine which particles caused the greatest damage. It wasn’t the 40-µm particles or the 10-µm particles, it was the tiny 3-µm particles (see Fig. 3).

By the time you can see water in oil, the life of the bearing has been halved.

By the time you can see water in oil, the life of the bearing has been halved.

According to Tranter, personnel may think that if they can’t see water in oil then the oil must be fine. Sadly, that is not correct (see Fig. 4). By the time water can be seen in the oil, the life of the bearing has been halved. “We could continue the discussion,” he said, “but suffice it to say that there is a great deal we can do to avoid problems that arise due to imperfect maintenance and operating practices.”

#2. Cause of Reliability Problems: Desire and organizational culture

It’s one thing to understand all of the above root causes. “It’s another,” Tranter observed, “to obtain approval to establish standards and purchase all of the tools, such as laser-alignment systems, that enable technicians and operators to do their jobs correctly. But owning the tools and having standard operating procedures won’t solve the problem.” As he put it, the problem will only be solved when technicians and operators want to use those tools properly and are given the time and encouragement to do so.

Thus, the issue of “desire” and its link to organizational culture must be considered as a root cause of self-inflicted reliability problems and addressed accordingly.

#1. Cause of Reliability Problems: Inadequate management support

Tranter believes a strong case could be made that the root cause of all failures derives from lack of senior-management support for a culture of reliability. Without their support it will be impossible to change the culture and thus change behavior.

“Think about initiatives to improve safety at your plant,” he said. “If senior management didn’t support them, would those initiatives have been successful? Senior-management support leads to people being employed in safety roles, investment in training and tools, and posting of signage that provides warning and feedback on progress, among other things. It also keeps sites from cutting corners that would risk safety, and it makes it clear how important safety is to the future of the organization.”

According to Tranter, the type of management support that drives safety at a site needs to be leveraged to drive reliability improvement. “Everyone within the organization,” he said, “needs to understand that reliability is critically important to the organization and that senior management will stand strong when shortcuts that compromise reliability are available.” Without adequate senior management support, he concluded, meaningful culture change won’t occur, and reliability-improvement initiatives won’t be able to eliminate self-inflicted root causes of problems. MT

Jason Tranter, BE (Hons), CMRP, VA-IV is CEO and founder of Mobius Institute (Balnarring, Victoria, Australia, and Bainbridge Island, WA). For more information on this topic and other reliability issues, including vibration monitoring and training and certification of vibration analysts, contact him at jason@mobiusinstitute.com, or visit mobiusinstitute.com.

Where Does Condition Monitoring Fit?

By Jason Tranter, Mobius Institute

Condition monitoring plays several crucial roles in the battle against self-inflicted reliability problems. For example, providing an early warning of impending problems minimizes the impact of premature failure, and detecting and eliminating the root causes ensures that we achieve the greatest life and value from our precious assets.

Many plant personnel, however, believe that if they have a condition-monitoring program in place, equipment reliability will be optimized. That, unfortunately, is not true.

Most detected faults are avoidable. While it is important to get an early warning, it is much more important to avoid the problem in the first place. Condition monitoring can help by detecting the root causes of failure, including misalignment, unbalance, lubrication issues, and looseness, among others. If those problems are cost-effectively nipped in the bud, then we avoid future failures.

Another way condition monitoring plays a role in plants is in acceptance testing. As part of the purchase agreement, condition-monitoring specialists can perform tests to ensure the new or overhauled equipment is “fit for purpose.”

You may be surprised at how many problems you actually bring into your plant.

304

7:42 pm
April 13, 2017
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Top Tips For Maintaining Air Compressors

Use these tips to improve air-compressor performance and increase uptime.

Use these tips to improve air-compressor performance and increase uptime.

Air compressors and their output are valuable assets on which countless plants depend for efficient daily operations. Regular attention to and proper management of the health of these critical equipment systems can save time and money in all manufacturing systems.

John Skalka, service manager for Sullair (Chicago) offers several tips for maintaining your site’s air compressors. According to Skalka, following these procedures to help monitor and maintain air-compressor performance can result in reliable equipment and reduced downtime.

—Jane Alexander, Managing Editor

Maintain filters and separators.

Proper maintenance of a compressor’s consumable filters and separator elements will not only help to ensure maximum unit uptime, but also maximize its efficiency and performance.

Air intake and oil-filter maintenance should be conducted every 2,000 hr. Monitor the oil filter for contamination and wear metals, leading indicators that air-end maintenance is required.

Air/oil separator elements should be changed every 8,000 hr., along with compressor fluid. Proper air/oil separator maintenance will ensure oil carryover stays within the manufacturer’s specifications.

Remember that use of OEM service parts and lubricants in compressor maintenance will help ensure optimal equipment performance.

randmSample oil.

Regularly acquiring and analyzing oil samples helps monitor the condition of the compressor lubricant, as well as the unit itself. A robust oil-sampling and monitoring program will alert the user to fluid degradation resulting from increased viscosity, ingestion of chemicals or particulate, and high water content. It can also identify the presence of wear metals, which is a sign of bearing degradation, prior to catastrophic failure.

Oil-condition monitoring makes it possible to change the lubricant only when necessary to maintain peak performance. Samples should be drawn quarterly, during routine service maintenance on a compressor.

Remember to always draw your samples through a clean oil-sample port or from the center of the oil sump. Doing so will ensure that the results are free from particulate contamination.

Keep variable-speed drives clean.

Many of today’s compressors are equipped with a variable-speed drive (VSD) that increases efficiency and reduces energy consumption. While VSDs are electrical components, they are not completely maintenance free.

Most VSDs contain cooling fans and heat sinks that can accumulate dust and dirt during regular operation. Maintenance activities will help them run cooler and prolong their service life.

Eliminate the guesswork.

For plants that are unable to ensure regular compressor maintenance with in-house resources, outside support is available. Check with your local air-compressor sales and service center about plans that allow skilled, factory-trained technicians to routinely service your compressor(s) and related air-system equipment.

Finally, keep in mind that proper maintenance will help you realize years of reliable service from your compressor. MT

Sullair, part of Accudyne Industries (Luxembourg and Dallas, accudyneindustries.com) has been developing and manufacturing air compressors since 1965. For more information, visit sullair.com.

625

2:58 pm
March 13, 2017
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Keep Stored Gear Reducers Service Ready

When gear reducers and other capital spares are improperly prepared for storage, their service readiness can be seriously compromised.

When gear reducers and other capital spares are improperly prepared for storage, their service readiness can be seriously compromised.

Are your statically stored gear reducers service ready? That’s the first of several questions from Dillon Gully of Motion Industries (headquartered in Birmingham, AL, motionindustries.com). He has good reason for asking. In conducting borescope inspections of statically stored internal-gear reducers for customers, Motion Industries personnel discovered as many as one-third of these assets sitting on shelves in a failed state.

Next questions: Are you willing to gamble the OEE (overall equipment effectiveness) and profitability of your facility on gear reducers and, for that matter, other capital spares that might not be service ready? What would you tell your boss if a critical spare were to fail within mere hours? Think this scenario doesn’t apply to you? How can you be sure? Gully offers some advice for achieving peace of mind.

— Jane Alexander, Managing Editor

Effective management of capital spares involves up-front identification of these assets and making sure they are in service-ready condition prior to preparing them for long-term storage. Unfortunately, many operations don’t follow through on this process once purchased units arrive on site. According to Gully, these steps are the only way to support the reliability of stored spares.

Capital spares can be defined as any item that is critical to production, promotes safety, decreases downtime, and/or prevents environmental issues. Gear reducers certainly qualify. The best way of verifying that these assets won’t fail as soon as they’re put into service is to inspect them before they are stored away—perhaps for years. Minimally invasive borescope inspections are a particularly good inspection method.

In a borescope inspection of a gear reducer, a camera scope visually inspects the condition of bearings, gearing, and internal components. The procedure can be accomplished through a plughole, which prevents contamination of an asset, if it is, indeed, ready for service. (Compared to the cost of replacing a failed bearing, costs associated with borescope inspections are also minimal.)

randmStorage planning

While information gleaned from borescope inspections can be used to confirm service readiness—or help identify steps for making a spare service ready—it can also help determine how to prevent these units from improper storage.

Corrosion, i.e., rust and contamination, are two, of many, causes of failure in gear reducers. When borescope inspections identify the presence of these failure modes, steps can be taken to correct them before the equipment is put into storage, as well as prevent those problems from recurring during storage.

Once a plan to prevent failures in stored spares is developed and implemented, it should be consistently followed. Every unit that will be stored, for whatever period of time, should be carefully protected. Preventing rust and contamination is a great start in protecting asset reliability and, thus, ensuring service readiness.

An ongoing process

Keeping stored spares in service-ready condition requires management accountability. Someone must be assigned responsibility for these assets, and expectations should be clear and realistic. It’s the responsibility of that designated person to ensure all spares are properly prepared and maintained. Identifying failed spares and bringing them back to service-ready condition is an ongoing process. As Dillon Gully emphasizes, “It should not be done one time and then forgotten.”

This plan for reliability can lower the probability of failure and bring a welcome degree of certainty regarding your stored gear reducers and other capital spares. MT

Working as an analyst for Motion Industries’ service center in Pensacola, FL, Dillon Gully has been conducting vibration and borescope inspections and managing capital spares for three years. For more information on these topics, visit motionindustries.com or bearings.com.

358

3:56 pm
February 8, 2017
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How to Start a Predictive Maintenance Program

IIoT motorsDevice and equipment advances, on display in our MT IIoT web section, is past the early adoption stage, but operations and maintenance (O&M) teams are still wrapping their arms around predictive maintenance programs. A recent interview with ARC Advisory’s Ralph Rio via SAP’s Enterprise Asset Management discusses this very issue and more.

Excerpt below:

Q: So how do people begin moving toward predictive maintenance – how do they get there?

Ralph Rio: The first thing people need to do is to educate themselves to understand what is available from a technology standpoint. People just entering this area are no longer “early adopters” so there is plenty of information out there. Get comfortable with the platforms and the business processes.

Sometimes technology education is coming from your machine builder (OEM) with improved data acquisition capabilities. From this post, “Are Smaller IIoT Applications The Next Wave for End Users?” and discussion with Erl Campbell at Aventics, MT found out how this is working:

“By actually monitoring the spool position, the machine can track exactly how each valve performed during a motion cycle: where that valve started, whether it fully shifted or only partially shifted, and its final position. These data points help machine builders and end-user operators correct issues that may affect overall packaging quality and integrity,” the white paper states (written by Erl Campbell.

Campbell added in a recent interview that the company is working on whether the (valve) reliability data should communicate with the factory floor or maintenance. Is it going to be some kind of wireless communication or will techs plug into the manifold and download that data?

>> For more on how to create a predictive maintenance program with Ralph Rio

1601Iot_logoFor more IIoT coverage in maintenance and operations, click here! 

269

9:40 pm
January 13, 2017
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Properly Align Variable-, Fixed-Pitch Sheaves

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Variable-pitch sheaves are frequently used in air handlers. According to a blog post by Stan Riddle of VibrAlign (Richmond, VA, vibralign.com), they allow design engineers to increase or decrease the speed of the driven machine and, thus, provide:

• changes in motor amp draw to maximize efficiency

• increased or decreased static pressure and air flow.

Normally, a design engineer will specify the use of a variable-pitch sheave on the driver and a fixed-pitch sheave on the driven machine.

Performed on a single-belt machine, proper sheave alignment is simple, if a good sheave-alignment tool is used. When multiple belts are used, as they often are, proper sheave alignment can become more complex. A variable-pitch sheave can be adjusted to increase/decrease the sheave diameter. However, doing so also changes the sheave width, depending on the adjustment.

In his post, Riddle referred to a customer who was attempting to perform a sheave alignment on an air handler. The unit’s motor had a variable-pitch sheave, but the fan sheave was fixed. The customer stated that he could align one belt, but not the other.

As Riddle described it, the customer was struggling because the width of the fixed-diameter sheave was 1 5/8 in., but the width of the variable-pitch sheave was 2 3/8 in. Consequently, only one set of grooves could be aligned, meaning the other was out of alignment.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The solution

Riddle wrote that the solution to the customer’s problem was simply to split the difference between the width of the two sheave diameters, as shown in the following equation:

2 3/8 in. – 1 5/8 in. = 3/4 in. ÷ 2 = 3/8 in. offset on each groove

randmRiddle also noted that it’s important to keep in mind this approach will probably not align the components sufficiently to eliminate sheave and belt wear. In fact, such wear can’t be eliminated. Still, when it comes to aligning multiple V-belts on an equipment system, splitting the difference between the diameter width of a variable-pitch sheave and that of a fixed-pitch sheave to which it is aligned will make the belts wear evenly.

Variable-pitch sheaves are normally used to balance a system and achieve proper static pressure and speed. When that’s determined, according to Riddle, the variable-pitch sheave should be replaced with a fixed-pitch sheave of the proper diameter to match the desired speed and pressure. Once both sheaves are fixed-pitch, proper alignment can be achieved. MT

—Jane Alexander, Managing Editor

Stan Riddle, a technical trainer for VibraAlign, has spent more than 36 years aligning industrial machinery. For more information from him and other technical experts with the company, visit vibralign.com.

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