There are many sources of machinery health and production availability information available to an organization’s maintenance and operations staff. Two of the most commonly used sources of information are scheduled inspection of machinery and condition monitoring. In most cases, scheduled inspection of machinery has been managed through a plant (Read More) This paper will talk about the use of some new technologies to capture and retain inspection data, and methods that can be used to integrate inspection results and condition-based data. There will be several examples from organizations currently using these technologies, relating the challenges they have faced and the successes they have achieved.
In this paper, we will describe the methods and techniques that are covered by the term “equipment inspection”. The basic inspection process will be looked at, and we will discuss some of the drawbacks that limit the usefulness of manual inspection processes.We will then look at some tools that can be used to automate inspections, and how these tools can be used to ameliorate some of the issues of manual inspection.
We will then look at what is needed to bring the data collected by an automated inspection system into a general database system that can manage all types of machinery health monitoring data.
Finally, we will get feedback from some users who have actually applied these techniques, asking them why they felt this process is important, how they are doing and where they want to take this process in the future.
The Inspection Process
Inspections – A Valuable Tool
Inspection rounds have always been a part of the maintenance process. Having operations and/or maintenance staff go onto the plant floor, the garage or the engine room and check belts, fittings, seals, fluid levels etc. in an informal manner has been carried out since the Industrial Revolution. The more structured approach of scheduled, defined and documented inspection rounds was one of the fundamental concepts that came to be known as “Planned Maintenance”. Developed during the years of the Second World War, planned maintenance methods were applied as a means of assuring high levels of machinery availability. Over the next quarter century, planned maintenance and its numerous offshoots have been applied in all industry types in Europe and North America. At the same time, Japanese industry, faced with considerable challenges, developed a variant of planned maintenance now known as Total Productive Maintenance (TPM). As with planned maintenance, frequent inspections are a fundamental tenet of the TPM process.
“A very important aspect of TPM is the establishment of autonomous maintenance. The purpose of autonomous maintenance is to teach operators how to maintain their equipment by performing:
Replacement of parts
Early detection of abnormal conditions
As with most of the Lean Manufacturing techniques and tools, autonomous maintenance is based on education and training. It is about raising awareness of the operators on the knowledge and understanding the operation principles of their machines.” Kunio Shirose, TPM Consultant
Inspection processes can therefore be operations-driven or maintenance-driven; often they are a combination of both. The management of an inspection program is just as likely to be under the control of operations / production as maintenance.
Implementation of Inspection Procedures
An inspection program can be implemented as a separate program in and of itself, or as part of several broader programs. Given the different implementation methods, inspection rounds follow similar patterns, even across different types of industries. If the inspection rounds are formally scheduled at all, the scheduling is handled by the planned maintenance system. In many cases, since inspections are carried out on a daily or per shift basis, they are not scheduled as work orders; they are treated as part of the daily routine. Sometimes inspection results are entered back into the maintenance system (CMMS), but this is unusual – in most cases they are not.
Traditional inspection data collection tools are clipboards and check sheets. A series of check sheets are created for the inspector to follow. They can range from very informal (“if you see a problem, make a note on this form”) to very specific (“Check Sheet PMP-1A is specifically tailored for motor driven pumps in the finishing room. Please complete all sections. Use an X in the check boxes, not a tick mark.”) Typically, the only review mechanism available to determine if the work is being done is to read/review the check sheets.
In some programs, results are keyed into programs like Excel / Access etc. This requires either 1) clerical staff support, or 2) the use of maintenance / operations personnel to enter the data. These efforts are often subject to interruption or even abandonment if clerical support becomes unavailable or if the inspection sheet data entry becomes too heavily backlogged.
Challenges to Inspection Procedures
There are a number of challenges to the manual inspection process. Inspection programs using check sheets are difficult to monitor – many inspection rounds never get carried out, and it’s difficult to determine if they haven’t been carried out.
The data collected on inspection check sheets is highly prone to error – entries are illegible, different inspectors use their own terms to describe problem conditions, meter values are transcribed incorrectly.
This is difficult for the person reviewing the inspection results, and even more difficult if those results are required to be entered into a database or a spreadsheet.
Another source of error is simply that there is often confusion about which machine train is being inspected – especially in process industries where there is lots of identical equipment in operation.
The inspection check sheet offers little additional support to the inspector when he/she discovers what may be a problem – there isn’t any way to review previous inspections or query the check sheet for further help.
Finally, the inspection check sheets need to be reviewed by someone capable of taking the next step – either ordering work to be done or more tests.
Automated Inspection Methods
Even with the substantial challenges presented by manual inspection methods, the results are highly beneficial. Plants that have implemented these programs report substantial returns on investment and increased asset availability. The benefits of a properly managed inspection program have led to the adoption of new technology to reduce or eliminate some of the difficulties of paper-based inspections.
What is automated inspection?
Automated inspection involves the use of portable instrumentation to electronically capture the inspection results at the machine itself.
Inspection rounds, instead of being printed out as check sheets or work orders are downloaded to handheld computers, just like routes are downloaded to a vibration data collector. Instead of carrying a clipboard from machine to machine, the operator carries the handheld computer, entering observational and meter data into the computer.
The operator can either follow the machine order set in the handheld computer (walk the round) or the operator can choose to follow his own route, and use a bar code, touch button or RFID (radio frequency identification) scanner to identify the machine that is being inspected.
If the operator wants to make a note, he/she is able to use the pen and/or the keyboard to enter a note directly into the handheld computer.
Once the round is completed, the data is uploaded into a workstation (once again, just like uploading a vibration route). The operator is able to produce reports, generate alarms etc. At least one system exists that allow the automatic generation of corrective work orders based on the data collected in the inspection rounds.
Until recently, clipboards and forms were the only really effective tool that could be applied to basic machinery inspection. Commercial–grade laptop computers are too fragile to be taken out onto the shop floor. Devices designed for other types of data collection, such as vibration analysis, are rugged enough to be taken into the plant, but they are too expensive to be broadly deployed to operators, and they are not flexible enough to collect the data sets needed for effective inspection. In the last three years, a new type of device, the industrial handheld computer, has been applied to the inspection process. These units combine the ease of use of consumer grade PDA’s such as the Palm and the Pocket PC with the ruggedness of industrial instrumentation. They are generally equipped with touch screens and pens, like the consumer PDA’s. Some units also come equipped with keyboards.
The industrial handheld marketplace is relatively new, and highly competitive. As such, handheld computer hardware has been the focus of considerable research and development, with the happy benefit (for the users of this technology) that the price / performance ratio of these units has dropped considerably since their introduction.
Advantages of automation
Direct Data Capture
All data is captured at source, minimizing the possibility of error and eliminating the need for keypunching.
Using pre-defined pick lists (Figure 3) and comments ensures consistency of data throughout the plant, improving the ability to use inspection data as a decision support tool.
Proper Machine Identification
Industrial handheld devices can use integrated bar coding or other identification tags (RFID, touch button, etc.) to ensure that the operator is collecting data about the right machine.
Improves Field-Level Decision Making
The operator can have alarms, historical trends, on-alert instructions and machine schematics downloaded into the handheld device or available through a wireless link. This allows the operator to receive further instructions in the event of an alarm while he is at the machine.
Automatic Escalation of Detected Problems
Manual inspection methods require someone (either the person doing the inspection or the person reviewing the inspection check sheets) to notify the maintenance planner of the existence of a problem. Electronically recorded inspections can automatically notify the CMMS to schedule follow-up work to confirm or fix the problem.
If the inspector detects a problem and remedies it (adds lubricant, cleans up a spill etc.) he now has to record that this work was carried out in the CMMS. Handheld devices can allow the inspector to record.
Any work done while performing the inspection round – even on machines that are not in the inspection round. “What Gets Measured, Gets Done” The recording of data collected during inspections ensures that the inspections and basic care routes are carried out, and that missed or skipped inspections are apparent immediately.
Integrating Inspections With Condition Monitoring
Inspection programs are one of the most powerful tools available for moving plants away from breakdown maintenance into a planned/preventive maintenance regime. Predictive maintenance programs are being carried out with considerable success in every type of industry around the world, and are seen as logical extensions of the inspection-driven preventive maintenance program.
The methodology of PM-based inspections and predictive maintenance programs are fundamentally the same – create a list of items to check, and then go out into the plant and check them on a routine basis.
The underlying purpose of PM-based inspections and predictive maintenance programs are also fundamentally the same – look for situations that are out of the norm, and then arrange for some action to be taken to bring them back into line. Information collected by the inspection process can be very helpful to reliability personnel who are looking for machines that are operating abnormally. Conversely, the operations and maintenance can find reliability evaluations very valuable when developing maintenance and production schedules. It stands to reason that there would be considerable benefit in bringing all machinery health data (including inspection results) together into a single “common area”. All interested parties within the organization (operations and maintenance, specifically) could have easy access to that data.
Although there are many similarities in the data sets gathered by inspection processes and condition monitoring processes, there are several key differences that need to be addressed before an effective integration can take place.
Broader Scope Of Data
The technologies used in condition monitoring are, for the most part, equipment-centric. Tools such as vibration analysis, lubricant analysis, ultrasonic testing etc. are primarily concerned with the health of the equipment being tested.
Inspections also focus on the health of the machine, but they can be equally concerned with environmental, quality and performance issues. In a single inspection round, data may be collected on bearing surface temperature (a condition monitoring process), the amount of fluids being consumed by a particular machine (an environmental process), the amount of power consumed versus product produced (performance) and the amount and reasons for scrapped product (production quality).
Anyone attempting to integrate inspection data with condition monitoring data (especially if they are trying to bring inspection data into a condition monitoring software) needs to recognize the broader scope of inspection surveys.
2) Numeric Versus Non-Numeric Data
Condition monitoring data is primarily numeric in nature (thermography data and analytical ferrography images are notable exceptions). Most condition monitoring systems reflect this fact – they are designed to import, store and alarm on numbers. For the most part, text-type data handling is an afterthought.
Inspection data sets can have numeric values (meter readings, counts, etc.) but a substantial portion of inspection data is non-numeric. Notes, single selection pick lists, multi-selection checklists, etc. are all fundamental elements of an inspection check sheet. In addition, it is necessary to be able to specify alarm conditions based on these lists – for example, being able to raise an alarm if the inspector identifies a fault in a pick list.
Record of Compliance
Another area of difference between condition monitoring data collection processes and operations-based inspection is the emphasis placed on record of compliance. Most condition monitoring programs do not have a heavy emphasis on compliance record keeping – because it’s not really necessary. When data is being collected once a month or even once a week, a simple overdue measurement points report will suffice to let you know if any points are being missed. The same level of tracking is usually enough for oil samples, thermography readings etc.
In the operations inspection world, readings/observations are often recorded once a shift, sometimes even more frequently. A missed point is quickly masked by the inspection done by the next shift. If these readings are being used to calculate metrics such as OEE or average productivity by shift, missed readings can skew the values of these metrics. Therefore, inspection systems require the ability to track and trend, not just the inspection data itself, but the record of compliance in collecting the inspection data. A high level of compliance is needed before metrics generated from the inspection data can be used with confidence.
Common Data Infrastructure
Bringing information from inspection programs and condition monitoring programs together effectively requires a common data infrastructure. Put simply, it means that every system that is used to collect data on a building, a machine train within the building, and/or a component within the machine train must use the same identifiers. These identifiers include location id, machine id, component id, and bar code value (if bar coding technology is used). If multiple technologies are used to gather data on individual bearings (like vibration and temperature) the method used to identify bearing location (drive end / non drive end, inboard / outboard, A-B-C-D etc.)
Given that some inspection data does not focus specifically on equipment (for example, environmental surveys) that common data infrastructure must allow data collection points to be applied to facilities, processes, and a number of other entities beyond the equipment.
Common Result Delivery Method
Setting up a common data infrastructure and making sure that your inspection database system can handle both numeric and non-numeric data will not amount to much benefit if you can’t analyze or report on condition monitoring and inspection data in a unified fashion. All of your data management systems should at least have the ability to expose their data in a readily accessible fashion so that common reports can be generated. This can range from the ability to export data to something like Crystal Reports™ or Microsoft™ Excel™, or it could be a more advanced capability such as XML that allows data to be accessed by a wide variety of reporting tools.
Inspection rounds have always been a part of the maintenance process, and, thanks in part to TPM, they are also now seen as an operations tool as well. There are a number of challenges to programs based on the traditional inspection check sheet. Some of these challenges are include error-prone data, confusion about machine train identification, no access to previously collected data and often-ignored data review requirements.
Automated inspection involves the use of portable instrumentation to electronically capture the inspection results at the machine itself. Some of the advantages of using inspection instrumentation are:
- Direct data capture
- Proper machine identification
- Improved field-level decision making
- Automatic escalation of detected problems.
- Record of repairs carried out
- Improved ability to ensure inspections are carried out.
It is perceived that there is considerable benefit in bringing condition monitoring data together with inspection results into a single “common area. Although there are many similarities in the data sets gathered by inspection processes and condition monitoring processes, there are several key differences that need to be addressed before an effective integration can take place.
Inspection data sets have a broader scope than machine condition monitoring data sets.
Inspection data sets have a substantial amount of non-numeric data – condition monitoring data is primarily numeric in nature.
The system should offer some form of record of compliance with the data collection schedule – an area of significant importance for operations-based inspections.
Some form of common data infrastructure is needed to make sure that inspection findings can be matched up to condition monitoring findings
Some form of reporting or analysis tool that can access and combine the inspection and condition monitoring datasets into a unified report.
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