Archive | July, 2002

236

1:33 am
July 2, 2002
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Communication Is the Mortar of Maintenance Excellence

Getting a program to stick requires communication with all affected parties.

Identifying the key elements to a maintenance excellence program and putting them together with a little communication mortar will form the foundation of a maintenance improvement effort. To focus on a few elements, planners must be assigned, a computerized maintenance management system (CMMS) must be implemented, and spare parts managed. Work management processes must be defined, preventive and predictive maintenance programs must be developed, and maintenance performance tracked. Training is also a key element in this process.

In all these efforts, communication to and among all affected parties must take place. Without this key ingredient, the maintenance excellence effort will not take hold.

Maintenance planners
When proposing the idea of maintenance planners, considerable effort must be expended to sell this concept to upper management who often is operations born and bred. To simply express the desire to add or reassign people to planning because maintenance thinks it is a good idea will usually fall on deaf ears. An important part of this task is to effectively communicate the “opportunity” to this part of the organization.

This opportunity is production capacity increases and worker efficiencies/reductions that will be achieved by making this change in organizational structure. Industry statistics and maintenance history records, if they are available, can be used to calculate these gains. Planned maintenance is three times more effective than unplanned maintenance. Well-planned maintenance also prevents re-work, which can affect equipment uptime. Quality of the product can be affected by poor maintenance practices. These are just a few examples that can be used to calculate the opportunity.

The true savings garnered by implementing maintenance planning can be significant, but beware, especially in communicating these numbers to an already skeptical group. Poor past performance by maintenance departments working in an unplanned reactive mode can be responsible for this skepticism. A detailed action plan should be developed which will show how planners will be selected and what their responsibilities will be in the organization. Realistic yet conservative savings and improvement projections will help get upper management into the mix.

CMMS
To make these new planning groups effective, the next element of maintenance excellence that must be well communicated is the need for a CMMS. Planning groups can function without one, but not very efficiently. To achieve maintenance excellence, a CMMS is a requirement. Communicating this need is one of the most daunting tasks because upper management often lacks understanding of what a CMMS does for the maintenance organization.

Another hurdle is the cost. Application service provider (ASP) models may help since this software can be leased for a low monthly fee instead of a capital investment. Considerable time should be spent outlining all the functions and capability that a CMMS will bring to the company. Equating this tool to a production control computer system can be a good analogy. The information needed to manage the maintenance process is similar to the important information a process control system brings to the production process.

Outline what each module can do to enhance the maintenance organization’s ability to manage the maintenance process and increase production capacity. These figures will be needed to calculate the return on investment (ROI) or payback. Make sure this payback can stand up to an audit down the road.

Spare parts management
Another key element needed to achieve maintenance excellence is spare parts management. Depending on the situation, the resources and infrastructure required to manage and house these important assets may need to be identified. Again industry statistics can be used to calculate these savings, or there may be historical data for the plant.

Spare parts management can be a huge undertaking if parts are not presently inventoried in the plant. Communicate to upper management how a spare parts inventory and control system will make the planning system more effective and efficient. Time saved not having to look for parts, money saved not buying duplicates, and eliminating/selling obsolete spares can add up to a substantial return on investment.

Work management process
The next step is to focus on identifying the best work management process for the organization. To obtain buy-in by all parties, they all need to be involved. The communication mortar used here will help bring the parties together. In many cases this is a complete culture change. Some maintenance people will not want to be part of this activity because they are comfortable with things the way they are now. Operations personnel may feel this process is just for maintenance personnel. All these people must be involved in defining this process.

Simple flowcharts can facilitate these discussions. The charts must show how communication between maintenance, planning, and operations cements the work management process. This process must be treated with the same importance as every other business process in the organization.

After defining the process, the roles and responsibilities of those involved must be defined. Job descriptions should be developed for each member of the organization. These roles must be defined with emphasis on the interaction with all groups involved. Daily and weekly meetings with operations and maintenance must be set up to facilitate communicating priorities and scheduling maintenance activities. The planning group should facilitate these meetings. With priorities identified, the planning group can now be certain what jobs to plan first. Work that has been properly planned can now be scheduled.

Preventive maintenance programs
Preventive maintenance (PM) programs must be developed or optimized if already in place. Once again, communicating the need for this element is important. Developing a comprehensive PM program can be time intensive and must use key resources in the organization.

High delay areas are a good place to start to identify the need for PM tasks. Defining equipment criticality also will help identify which equipment needs preventive tasks developed first. Bringing the appropriate parties together to develop these programs will not only ensure that the program is comprehensive, but also educate those who may be unfamiliar with a proactive approach to maintenance.

Predictive maintenance programs
Similar to the effort required for a comprehensive PM program, a good predictive maintenance program often can be the cornerstone of equipment reliability.

Vibration monitoring, thermography, and oil analysis should be performed at regular intervals and tracked through the CMMS. When problems are found, followup work orders should be generated and routed through the work management process. Communicating impending failure can allow maintenance to plan and schedule the needed overhaul or replacement of the equipment.

Training
Training is needed in all facets of this effort in order for it to be successful. Training costs money and takes time, but both are well spent.

Maintenance planners must be trained on how to use the CMMS to its full potential, and they also may need to learn basic planning skills. Inventory management training may be needed if spare parts and materials are not presently controlled.

A lot of the training comes in the form of communicating what maintenance excellence is, and how it will be achieved using a well-defined maintenance process. People must be trained to run a production process and the same is true for the maintenance process. Straying from standard operating procedures will produce a substandard product on a production line. Straying from the maintenance process will produce mediocrity. There is no shortcut to maintenance excellence.

Performance tracking
The best way to communicate how the maintenance excellence effort is going is by first choosing a few key performance indicators (KPI) or metrics. Some examples are Percent Planned Work, Preventive Maintenance Completion Percentage, Maintenance Man-Hours per Production Unit, Backlog Weeks, Schedule Compliance, and Percent Delay.

All parties involved should agree to these measurements, and goals must be set. Elevating these indicators to the level of other corporate metrics will give them the importance they need and deserve. Weekly and monthly reporting of these statistics will keep progress (or the lack thereof) in front of those who are in a position to keep the effort on track. The old adage is true; what gets measured, gets done.

Good communication in each element of maintenance excellence will turn this effort into a way of life in your organization. Communication mortar cures slowly, so be patient. Maintenance excellence is not built in a day. MT


Randy Heisler is area manager of maintenance planning and cost control for Wheeling Pittsburgh Steel, Steubenville, OH; (740) 283-5718

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560

10:41 pm
July 1, 2002
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Spot Size Ratio Value Affects Accuracy

Thermographers who traditionally have relied on IFOV values should consider using ratio values instead.

As the art and science of infrared thermography has matured, infrared test equipment has evolved. Technological advances during the past 15 years have enabled equipment manufacturers to design infrared imagers capable of providing real-time noncontact temperature measurements. The evolution of modern imaging radiometers has progressed to the point that most commercially available infrared cameras are now capable of providing noncontact temperature measurements.

When using a radiometer to measure object temperatures, several important factors must be addressed. Among these are target emittance, atmospheric attenuation, spectral response of the imaging radiometer, and measurement spot size. While spot size is not defined in currently published standards, it is generally defined as the area from which radiometric or temperature data are derived.

For accurate temperature measurement, the spot size of the radiometer must be smaller than the target being measured. Should the spot size be larger than the target, error will be introduced into the measurement. The amount of error will be dependent upon a number of factors, none of which can be corrected for by any means including radiometric software.

Lack of spot size information
While many nonimaging radiometers now employ a laser sighting system to project relative spot size onto the object being measured, no such sighting system exists for imaging radiometers. As such, it is impossible for a thermographer to visually gauge the spot size of the imager in use. In fact, many thermographers mistakenly believe that imaging radiometers are capable of producing accurate temperatures equal to the pixel size of the imager.

Although many modern infrared imagers are capable of measuring temperature, infrared equipment manufacturers generally do not provide information regarding spot size or how to calculate it. In contrast, nonimaging radiometers have always expressed spot size as a distance to target ratio such as 50:1. Applying this ratio, at 50 in. from a target, the spot size would be 1 in. This methodology provides a simple and quick means for calculating spot size at any distance from the target.

To date, manufacturers of infra-red imagers continue to apply the “slit response function test” to imaging radiometers. From this test, the only figure consistently reported is the milliradian angle at 50 percent of the radiance received by the imager; this is known as the instantaneous field of view (IFOV). The results of the slit response function test enable a user to calculate minimum target size or the distance at which there is a 50 percent probability of detection of a target.

IFOV problems
Applying the slit response function test values poses several problems. Among them are:

  • Because the slit response function test is a measure of the visual performance of an infrared imager, it has no bearing on the temperature measurement accuracy of an imaging radiometer.
  • Slit response values do not state the geometric configuration or orientation of the target tested.
  • The slit response test values do not specify the orientation of the detector during testing.
  • Since quantitative thermographers are interested in accurate temperature readings, temperature measurements based upon 50 percent accuracy are of little or no value to them.

spot_size_tableBy following the “Guideline for Measuring Distance/Target Size Values for Quantitative Thermal Imaging Cameras” published by the Infraspection Institute, the authors were able to calculate spot size ratio values for several modern imaging radiometers for varying percentages of accuracy. See “Table 1 Distance to Target Ratio Values for Imaging Radiometers.”

The information contained in Table 1 was derived using the normal lens supplied with each imager. Using telephoto or wide-angle lenses on any imaging radiometer will change ratio values proportionate to the magnification power of the lens. For example, using a 2x telephoto lens will effectively double the ratio values in Table 1; use of a 2x wide-angle lens will effectively halve the listed values.

Several interesting observations were made from the data obtained during testing:

  • Spot measurement size for the radiometers tested varied considerably from the theoretical values obtained by using published IFOV values.
  • In some cases, the visual IFOV was up to five times smaller than measurement spot size calculated from Table 1 values.
  • Target shape influences spot measurement size.
  • Some imaging radiometers had lower values when the target was horizontally oriented; others had lower values when the target was vertically oriented.
  • Most imagers performed worst on circular targets.
  • For some imaging radiometers, the on-screen crosshair did not always define the center of the measurement area.
  • Using electronic zoom did not change measurement spot size.
  • The distance to spot ratios listed in Table 1 can be used to calculate the maximum distance for accurate temperature measurement. For greatest accuracy, one should be conservative in applying these numbers.
  • Spot measurement size varies linearly as distance to the target increases or decreases.

Calculate target size, distance
The distance to spot ratios listed in Table 1 can be used to calculate either the minimum target size or maximum distance at 98 percent accuracy.

To calculate the minimum target size at a given distance, divide the distance from the camera lens to the target by the listed value that corresponds to the shape of the target.

Minimum Target Size = Distance/Listed Value

For example: You want to measure the temperature of a circular target 10 ft away with Imager #3:

Circular Spot Size =10 ft (120 in.)/212 = 0.566 in.

To calculate the maximum distance for a given target size, measure or estimate the size of the target and multiply the listed value by the target size to obtain the maximum distance.

Maximum Distance = Listed Value x Target Size

For example: You are inspecting a 1 in. circular target with Imager #6. How close should you be to measure the temperature?

181 x 1 in. = 181 in. or 15.08 ft

Applying the figures in Table 1, thermographers can develop simple diagrams similar to those commonly used for spot radiometers.

Compare IFOV, spot ratio values
Since many thermographers have long used IFOV values to calculate spot size, it is interesting to note how greatly this method differs from our results. The formula is as follows:

Spot Size = [IFOV (in milliradians)/1000] x Distance to target

Using the published IFOV values for Imager #2 at 30 ft (360 in.) from target, we calculate:

(1.3/1000) x 360 in. = 0.468 in.

Using IFOV value does not consider target shape nor does it state a percentage of accuracy. In fact, this value is derived with the radiometer receiving only 50 percent radiance from the blackbody simulator. IFOV values do not relate to spot size since they are a measurement of individual pixel size. Most imaging radiometers require more than one pixel for accurate temperature measurement. Since detectors vary among manufacturers so will the number and orientation of the pixels required for accurate temperature measurement.

Using the calculated ratio values from Table 1 for Imager #2 at 30 ft (360 in.), we calculate:

Vertical rectangle: 360 in./175 = 2.057 in.

Horizontal rectangle: 360 in/379 = 0.949 in.

Circular: 360 in./144 = 2.500 in.

These spot sizes vary considerably from that calculated by using the IFOV value. As stated earlier, spot size must be smaller than the target in order to accurately measure target temperatures. Radiometric software cannot correct temperatures obtained with an incorrect spot size.

Conclusion
Using IFOV values does not provide meaningful data with respect to spot measurement size of an imaging radiometer. The Infraspection Institute’s “Guideline for Measuring Distance/Target Size Values for Quantitative Thermal Imaging Cameras” can be used to calculate distance to spot ratios for any imaging radiometer. This test can be set up with a minimum of equipment and facilities and provides meaningful data about an individual radiometer’s accuracy. Knowing a radiometer’s accuracy enables a thermographer to better understand his limitations when measuring temperatures.

Thermographers who traditionally have relied on IFOV values should consider using ratio values instead. This is especially true for anyone performing remote infrared inspections of small targets such as overhead power lines or substation components. In these situations, thermographers performing quantitative inspections should consider moving closer to subject targets or using a telephoto lens. MT


Warren C. Garber is a staff instructor and R. James Seffrin is director of the Infraspection Institute, 425 Ellis St., Burlington, NJ 08016; (609) 386-1281


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197

8:29 pm
July 1, 2002
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The Plan Stage: Aligning Maintenance with Business Goals

In my last Viewpoint (“Maximizing Asset Reliability Requires Reliability Driven Maintenance,” April 2002), I introduced a maintenance business process which I call the Reliability Driven Maintenance Process and identified its four stages: plan, assess, improve, and control.

In the plan stage, the maintenance strategy is aligned with the business goals of the organization. The assess stage analyses the performance of the asset. In the improve stage, work identification strategies are used to identify appropriate actions to address the causes of failures in a timely manner. Companies then move into the control stage for planning, scheduling, execution, and follow up.

Over the next several Viewpoints I will delve into each stage, discussing applicable supporting practices and technologies.

In the plan stage, the alignment of maintenance strategy with the business goals of the organization is accomplished by:

  • Reviewing current reliability practices and company goals
  • Identifying physical assets contributing to goals
  • Prioritizing to identify critical assets
  • Establishing targeted performance requirements

To review our current reliability practices we can perform a reliability assessment to compare our current performance and opportunities with world class maintenance practices. The assessment methodology I use is based on 10 years of global benchmarking research and consists of having focused interviews with all levels of the organization: plant floor personnel, supervisors and middle managers, and senior managers.

Once we understand where our reliability practices are in relation to best in class, we next need to understand what our company goals are. Quite often maintenance departments are executing strategies with no real understanding of what the company is expecting to accomplish. We then develop a plan to address deficiencies in our process and practices inhibiting our ability to achieve those goals.

Identifying our assets starts with having a good asset hierarchy. This hierarchy must be defined to:

  • The level at which maintenance is performed (parent-child relationships, definition of systems, subsystems, and components)
  • The level at which condition is monitored (condition information to be captured and trended)

Most companies have the first level covered because that is where they track costs. However, all too often, the second level is not adequately defined.

With a proper asset hierarchy, we then can prioritize to establish the critical assets that are going to be crucial in helping us to achieve company goals. This Equipment Risk Prioritization is expressed as Risk = Failure Consequence × Probability of Failure.

We can measure failure consequence against business performance criteria such as safety, environmental impact, quality, throughput or capacity, customer service, and operating cost. The result is a total consequence number for each asset. Many companies are assessing their consequence relative only to operating cost which means they are at risk in ways they are not even aware of.

Once we understand the total consequence of failure for each asset, we need to assess the probability of that failure occurring. Does the failure occur weekly or yearly? We then can assign a probability number which we multiply by our consequence number. The result is a relative risk number for each asset, clearly showing which assets are creating most of our problems. Those with the highest relative risk are most likely to impede our ability to achieve company goals.

The relative risk number identifies candidates for reliability improvement (by changing maintenance practices and/or equipment technology) and prioritizes capital projects.

The asset criticality number (a function of failure consequence only and independent of reliability) drives execution of the maintenance backlog.

The final step of the plan stage is to establish targeted performance requirements for these critical assets. What performance levels are these assets going to have to achieve in order to meet our goals?

The plan stage lays the groundwork for the rest of the Reliability Driven Maintenance Process and is the stage that most organizations are not doing. If your company is not doing something similar to what I have laid out here then you likely are not able to accurately determine what assets you should be spending your time and money on. MT
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242

7:00 pm
July 1, 2002
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Maintenance Information Systems For Midsize and Larger Organizations

EAM/CMMS software for maintenance and reliability organizations that require powerful and responsive information systems.

The information requirements of large plants have traditionally been satisfied by large software programs running on midrange and mainframe computers with terminals distributed throughout the plant. Today, many larger maintenance information systems run on multi-platforms using client/server, thin client, or browser-based applications. These systems help organizations implement their strategy to decrease downtime and increase the utilization of their resources, and can be viewed as a communication tool to help make better decisions.

Using these approaches, maintenance personnel can access information and work orders using personal computers (PC), Palm-type personal digital assistants (PDAs), or through a handheld computer running Windows CE served through a network by powerful computers running robust operating systems and databases. Other wireless and radio frequency devices to access information are also at hand.

In addition, some companies are acting as application service providers (ASP). Users pay a monthly per-seat fee to access the software through an Internet-enabled workstation. The ASP stores the program and the data on its server. Users always have access to the most current version of the program. This delivery method eliminates the need for on-site hardware infrastructure, system administration, and associated costs at the user’s end.

To meet the needs of the increasing number of companies that recognize the benefits of electronic transactions, some software suppliers provide web-enabled systems that support e-procurement within their own program or allow users to integrate their equipment asset management (EAM)/computerized maintenance management (CMMS) system with other vendor software.

Another growing area is EAM connectivity with programs having the ability to integrate with other plant ERP business applications and production automation systems.

The relational database manager used by a program is an important selection factor for organizations with other business or back office software. If the database managers are the same, it is likely that the EAM/CMMS can work with these other applications.

The database manager is a significant contributor to the performance of an EAM/CMMS. It handles procedures that otherwise would have to be written into the application software, adding to its complexity. Many EAM/ CMMS programs are written to run with a variety of databases. Other programs are written for a single database, which allows them to make better use of the features and development tools provided by the database. ODBC indicates compliance with Open Database Connectivity, an SQL-based interface from Microsoft designed for consistent ac-cess to a variety of databases. MT

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