Dr. Nihat Çankaya
Necmettin Erbakan University
Meram Vocational School Department of Food Processing

1. INTRODUCTION

Unexpected breakdowns and downtimes in grain mills cause more trouble for today's mills due to their high production tonnage. These malfunctions cause a decrease in production capacity and delays in shipment. In general, the production costs due to malfunctions are much higher than the expenses for the elimination of the malfunction. In fact, some malfunctions cause quality fluctuations that can reach customers. The material dimension of such problems will never be determined clearly. However, reducing the unexpected failure rate is not an easy task considering the number of personnel, the time that the machines stop for maintenance and the maintenance costs. In this study, how a successful mill maintenance management can be done under the overwhelming pressure of increasing competition conditions and the contribution of advanced technology to maintenance management are explained.

2. NECESSITY OF MAINTENANCE ACTIVITIES

The level of maintenance activities to be carried out in the mill or in any industrial facility is determined by the negativities that will arise in the absence of maintenance. All working electrical and mechanical parts have an expected life according to the working conditions. In addition, they need functions such as lubrication, which must be done routinely in order to fulfill their functions. If these activities are not carried out, the machines will not be able to continue their work and will stop at an unexpected time. Failure to stop the production unexpectedly due to a malfunction in the machines is called a breakdown stop. Failure stops are serious problems for production. Some of the problems caused by fault stops are listed below.

•Products cannot be delivered to the customer on time.

•Due to the stop and re-start of production, quality fluctuations occur until the system is back in order, and the rate of second quality and scrap products increases.

•Energy consumption increases.

•During the downtime, the production team remains idle and labor costs increase.

•With a small budget to be allocated for maintenance, downtimes are significantly reduced. If this budget continues to increase, the downtimes will not continue to decrease at the same rate (Figure 1).

•The resulting malfunctions cause significant damage to the machines. For example, a problem that can be solved by changing only one bearing during the maintenance period, in case of failure, also disrupts the machine housings, causing an incomparable increase in maintenance costs. For this reason, while determining the targeted breakdown time rate and the budget allocated for it, other costs caused by the breakdown should also be taken into account (Figure 2).

3. BASIC MAINTENANCE TERMS

The main purpose of maintenance activities; it is to ensure the elimination of downtimes that will cause the production to stop unexpectedly. Today's maintenance management is evaluated under the following three main headings. These; It is named as Failure Maintenance (Repair of Unexpected Failures), Periodic Maintenance (Planned Maintenance) and Preventive Maintenance (Proactive Maintenance).

Failure maintenance includes repairing and re-commissioning the malfunctioning machine. The occurrence of the malfunction is due to the inability to perform the desired maintenance. However, some malfunctions occurs due to unavoidable conditions, too.

Periodic maintenance is the classical solution method applied to prevent unexpected downtimes, and it is the maintenance of the machines at regular intervals in order to ensure the smooth operation of the machines. In this maintenance, life parts such as bearings are replaced. The abrasions in the machines are detected, the problems that cause this are eliminated. The missing oils are added or replaced. Moving parts are lubricated.

Preventive maintenance, on the other hand, is the whole of activities carried out to completely eliminate the need for periodic maintenance, to extend the maintenance period, to make repairs by predicting the points where malfunctions may occur, and to reduce maintenance costs. It is an activity in which technology is also used intensively, and it is the highest point of today's maintenance philosophy. It is the type of maintenance that should be taken as a basis, especially for businesses that work 24 hours a day. The philosophy of the activities to be carried out within the scope of preventive maintenance, which is a proactive approach, can be listed as follows.

1) The primary goal is to identify the equipment in need of maintenance and replace them with maintenance-free equipment. An example of this is the elimination of oil change by replacing oily vacuum pumps with oil-free vacuum pumps.

2) If the need for maintenance cannot be eliminated for technological or financial reasons, changes should be made to extend the period of periodic maintenance. An example of this is the doubling of the oil change period by using synthetic oil instead of changing the oil every year using mineral oil.

3) By using high technology, the potential for disruption should be determined in advance and the need for planned maintenance should be postponed as much as possible. An example of this is the use of Jetmaster type artificial intelligence-based advanced control devices in jet pulse filters. Thanks to this device, problems in filter bags can be detected just in time. Bag change times can be determined by measuring clearly. Thus, the maintenance period is extended as much as possible, but maintenance is carried out before a malfunction occurs that may stop production.

Figure 3. A Jetmaster device with artificial intelligence technology.

4) Risk analysis should be done by listing all the malfunctions that may occur while the maintenance plans are being created. The frequency of these failures and the damage to production should be scored. According to the value obtained from the product of these two values, priorities are determined and malfunctions are ranked. Then, all the risks in this list should be tried to be completely eliminated, if this cannot be done, maintenance activities should be planned to reduce the risk. Points with a risk value above the determined threshold should be defined as critical control points. These risky points should be checked periodically against possible malfunctions and records should be kept.

4. CAUSES OF MALFUNCTIONS

The main reasons for the failures that cause unexpected breakdown stops can be counted as failure to establish an effective maintenance management system, not operating the maintenance process effectively, not keeping records properly, lack of qualified maintenance personnel, not allocating sufficient time and personnel for maintenance. Another important reason is that the personnel who are closed to innovation and development cannot keep up with the current technology. Some of these problems are the formation of operational blindness in the personnel working in the same enterprise for a long time, the inability to follow the technological developments and innovations in the sector by the operating personnel. Failure to make timely lubrication and bearing changes is one of the clearest reasons for failure. Some unavoidable reasons are the preference of machines that are more prone to malfunction due to being cheaper in the first purchase, the aging of the machine park, the old technology and the equipment that can easily break down. Quality problems and energy fluctuations that may occur in the electrical network, manufacturing errors in the equipment used can also be evaluated within this scope. 

Failure of the top management to give importance to maintenance work, not providing the training needed by the personnel, the cost of the resources spent for maintenance in some sectors is higher than the cost spent for the breakdown, and therefore the stopping of the maintenance activities are among the reasons that cause malfunctions.

5. MAINTENANCE MANAGEMENT SYSTEM (MMS)

Today's competitive conditions force mills to engage in activities such as developing value-added products and improving product quality. Undoubtedly, a company that is still struggling with production disruptions and the quality fluctuations caused by these will not be able to focus on more qualified operations. In order to overcome these problems, an effective MMS should be established and implemented effectively. Some of the features that an MMS to be installed in mills should have are listed below.

•The MMS to be installed should be suitable for the sector. MMS should be supported by senior management and the necessary resources should be provided by management.

•MMS effectiveness should be measured with performance criteria and performance criteria should be determined realistically.

•A reward system should be applied to meet the performance criteria.

•The basic operation of the MMS must have been documented. MMS; It should be associated with ISO 9001, food safety, occupational safety, environmental management systems.

•MMS should be managed by a technical staff with industry experience.

•The maintenance process should be carried out by both technical and production personnel, but the main responsibility should lie with the production operators who use the machine.

•Maintenance should be recorded. These records should be easily accessible.

•The paperwork load should be as low as possible. Here, the document is the vehicle, and the actual maintenance to the machines is the purpose. Foreign management systems that will increase the paperwork load, not the maintenance activity, should be avoided.

•Routine maintenance should always be performed by properly trained production operators. Only operations beyond the merit of the production personnel should be performed by the maintenance team.

•Maintenance responsibility should be given to the production operator and the personnel should be ensured to take care of the machine at the maximum level.

•The maintenance team should consist of trained personnel with electrical and mechanical competence, including engineers. Personnel open to innovative development should be supported.

•Operational blindness is one of the most important obstacles hindering the maintenance process. Personnel who have seen new and different enterprises should be reinforced into the maintenance teams that have personnel working in the same enterprise for more than ten years.

•A part of the maintenance work should be provided from external suppliers, so that current developments should be followed.

•MMS should have a preventive maintenance philosophy, have a perspective that will completely eliminate the failure event and solve the problem radically.

•Technology should be utilized at the highest level in MMS. In particular, the resistance of the personnel who do not keep up with the development to technological development and change should be broken, and working with these personnel should not be continued.

•For the continuous improvement of MMS, the contribution of all personnel to the process should be ensured and the personnel should be encouraged to suggest corrective and preventive action.

6. PERFORMANCE CRITERIA FOR MMS

For an effective MMS, some performance criteria should be selected, targets should be set for these criteria and followed regularly. Some MMS performance criteria that can be used in the mill are given below.

1) Breakdown Time Rate: It is the ratio of the time stopped due to the malfunction to the total time until the production is completed.

2) Number of Replaced Bearings: There are many equipment in the mills, especially electric motors that require periodic bearing replacement. The number of bearings replaced in a year by the maintenance personnel is an important criterion that shows the intensity of maintenance activities.

3) Budget Used for Maintenance: Another parameter that shows the feasibility of maintenance works is the maintenance budget. Undoubtedly, maintenance can only be done within the budget. 

4) Number of Maintenance Personnel per Electric Motor: The number of electric motors in mills can be taken as a reference in the analysis of many basic criteria. This is a parameter that analyzes whether there is a sufficient number of maintenance personnel.

5) Number of Corrective and Preventive Action Suggestions per Personnel: It is a parameter that shows the support and contribution of the production personnel to the maintenance process.

7. AN EXAMPLE OF ADVANCED TECHNOLOGY USE IN MAINTENANCE ACTIVITIES

JETMASTER Advanced Controller and Fault Analyzer for Jet Pulsed Filters:

Technology is the most effective competitive element. Jetmaster advanced jet filter control and fault analysis system can be given as an example to the devices with artificial intelligence technology, which are used in maintenance activities and provide significant advantages to the business. These technological devices, which are widely used in most of today's large mills, provide great convenience to the production personnel. 

Thanks to this device, the pollution rate of the filter bags, the change time of the filter bags, perforation on filter bags, the filter bag drop, the inability of blowing of some filter bags, perforations at the diaphragms can be determined. In addition, air leaks, perforation of the filter tank, blower failure, blockage of the blower filter, lack of pressure in the filter air tank, late rise in the pressure of the filter tank, not reducing the pressure sufficiently when blowing into the filter bags are detected immediately. In addition, these faults are also monitored on the main SCADA screen of the mill, and there is no need for the personnel to go to the jet filter for a malfunction. Figure 1 shows a working Jetmaster device [1].

8. CONCLUSION AND RECOMMENDATIONS

Today's milling is on the eve of switching to unmanned production. In order to exist in the sector, production-related problems such as breakdown stops must be completely resolved. Because these problems prevent us from focusing on essential works. In order to eliminate manufacturing problems, a very effective MMS should be established and this system should be implemented effectively. The technology developing in MMS operation should be transferred to the mills rapidly, maintenance burden should be reduced and competitiveness should be increased thanks to artificial intelligence devices such as Jetmaster.

References:

[1] Çankaya, N., & Özcan, M. (2019). Performance optimization and improvement of dust laden air by dynamic control method for jet pulsed filters. Advanced Powder Technology, 30(7), 1366-1377.

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