4.4 Standardization of Maintenance Activities
Since maintenance encompasses such a wide range of complex activities, from daily routine maintenance through equipment inspection and repair to corrective maintenance, good results cannot be achieved if people try to do it on their own. It is essential for each company to create a comprehensive set of maintenance standards embodying the
experience and technology relevant to their particular circumstances. This is also a prerequisite for accumulating and disseminating maintenance techniques and skills.
(1) Types of maintenance standard Maintenance standards can be classified broadly into three types according to their particular function: maintenance management standards, equipment maintenance standards, and maintenance work standards. Table 6.6 gives further details of these.
Table 6.6 The Three Main Types of Maintenance Standard
(2) Standardisation issues, and key points for improvement
1 There is no point in having standards unless they are put into practice. Each company must do its own careful research, ensuring that it formulates standards appropriate to the levels of organisation, management and technology that it possesses.
2 Maintenance management standards
• The overall operation and management of maintenance must be standardized to ensure compatibility among the various individual maintenance systems, since this is what these systems are based on.
• Maintenance management standards often focus on how to get things done, without clearly specifying who is responsible for what. It is particularly important to base the maintenance standards on giving responsibility for managing the maintenance of individual equipment units to the production lines, under the umbrella of Autonomous Maintenance.
3 Equipment maintenance standards
• When preparing inspection standards, the most important thing is to decide what is to be inspected and how often it is to be inspected. Before this can be done, the MTBF figures for each part of the equipment must be analysed and efforts made to extend its working life through corrective maintenance (see Figure 6.12).
• It is not efficient to maintain all units to the same level. Standards should be created for the most important items of equipment first.
• Inspection standards should be written in a format that helps data recording and avoids having to create separate record sheets. If necessary, they should also include drawings and photographs to indicate the inspection points clearly.
• Standards for assessing and restoring conditions should be stated in terms of specific values and quantities in order to eliminate differences in the way different operators do the job.
• It is important to establish substitute characteristics by looking at how changes in quality characteristics relate to equipment performance, how deterioration relates to failure and so on, in order to reduce the number of items that must be inspected while still achieving the maintenance objective.
4 Keep maintenance standards up-to-date
Maintenance standards are a barometer indicating the level of maintenance technology achieved. However, as the company’s organisation and operations become more efficient, and improvements are made both to the equipment and to the technical and managerial methods used to maintain it, maintenance standards can easily become
outdated. They are also valuable teaching materials, so, besides making sure that easily followed procedures are in place for revising existing standards, writing new ones, and discussing what additions and modifications (both technical and managerial) are required, clear and precise rules should be laid down for revising the standards
thoroughly at least once a year.
(3) Maintenance Planning
1 Why are maintenance plans needed?
A company must have maintenance plans and schedules to ensure that the maintenance program is advanced efficiently, reliably and cost-effectively in harmony with the firm’s production schedules and maintenance capabilities. Maintenance plans and schedules should cover the items listed below:
• Maintenance tasks to be carried out regularly, as a matter of routine (cleaning, checking, lubricating, replacing components, adjusting).
• Periodic inspections and shutdown maintenance.
• Restoration or repair work arising from checking or inspection.
• Corrective maintenance (for improving product quality and enhancing operability, maintainability, safety, and cost effectiveness).
• Improvements for correcting failures and stopping them from recurring.
2 Maintenance plan sub-categories
As Figure 6.17 illustrates, the overall maintenance plan can be divided up according to the maintenance functions and time intervals involved, into maintenance plans prepared by the department responsible for overseeing the maintenance function, and a series of work schedules prepared by the department actually responsible for carrying out the work.
Figure 6.17 Maintenance Plan Sub-Categories
Figure 6.18 A Typical Effective Maintenance System
(4) Daily countermeasures
In the best of all worlds, the maintenance department will fulfill its role down to the last detail by rapidly gathering all information relating to each equipment failure (or minor stop that is the fault of the equipment), identifying the true causes behind it, finding and installing a permanent solution, and ensuring that the problem never recurs by deciding who will be responsible for the appropriate maintenance and revising the maintenance standards accordingly. It is particularly important to identify the true causes of failures.
Figure 6.19 shows a typical format of a maintenance record used for doing this. The key points to note in implementing daily countermeasures are listed below.
1 The failure phenomenon (what has actually occurred) must be ascertained accurately by examining the actual equipment and materials in the actual spot where the failure happened. Causes are particularly hard to identify in the case of intermittent faults, or failures that automatically correct themselves, but the source of the problem will always lie somewhere. To pinpoint that source, it is essential to subject to close scrutiny the structure of the equipment and components, their individual properties, and the conditions under which they are used.
2 Identifying causes requires the causal structure (whether it consists of single, multiple or complex causes) to be investigated in relation to the equipment mechanisms. P-M Analysis is useful for studying complex causal relationships.
3 Possible improvements are studied with the aim of increasing reliability at diagnosed weak points in the equipment, and proposals for preventing recurrence are put forward.
4 The previous three points are crucial for preventing breakdowns from recurring. They should not be left up to individual maintenance workers, but rather require a comprehensive design review process that draws on the technical knowledge and skills of department, area and line managers, as well as designers.
5 The ‘right-first-time’ rate for the action taken against equipment failures should be monitored with the aim of ensuring that countermeasures are actively promoted, permanent solutions are implemented, maintenance standards are revised where necessary, and all improvements are consolidated rapidly and securely.
Figure 6.19 Maintenance Record (example)
(5) Managing the actual maintenance work
1 Delays can occur in the supply of components. An order may simply be forgotten, deliveries may come in late, or components may turn out to be defective. Components must be managed reliably to prevent problems like these.
2 Tasks will be left uncompleted or done late if there are not enough staff. If this is the case, either the workload for each person or trade should be estimated and steps taken to reduce it (for instance, by employing more contract workers), or a priority ranking should be assigned to each item and the schedule reviewed. It is important to set up a
system that includes provision for subcontracting, to enable extra staff to be drafted in rapidly if the work falls behind schedule. The particular characteristics of the maintenance work must be taken into account when bringing in labor from outside.
3 Large-scale maintenance tasks, in particular, often take up a great deal of time, as they require lengthy preparation, and collaboration between different trades. To prevent delays and waste of labor, a PERT chart (see Figure 6.20-1) or other planning tool (such as a Gantt chart – see Figure 6.20-2) should be used to create an individual work schedule for this type of job.
4 Periodic shutdowns, and repair tasks relating to specific breakdowns, both present an opportunity to make improvements such as extending equipment life, improving maintainability, shortening repair times, etc. These improvements might include:
- Treating the surfaces of shafts and axles to reduce wear
- Introducing easily replaceable components and units
- Replacing permanent cable and pipe joints with quick-release ones
5 Maintenance work necessitates a lot of moving and carrying, but there are many ways in which it can be made more efficient, e.g. by improving the storage, location and method of transportation of tools and materials, the assignment of maintenance personnel to tasks, and so on (the operating efficiency of maintenance work is generally
around 30 – 40%).
6 Before individual maintenance tasks are actually started, every effort should be made to reduce the time and cost required. This can be done by employing various analytical methods, such as time and motion studies, performance monitoring, standard time data, or experience-based estimates. At the same time, the maintenance system should state exactly who is responsible for managing the work on site and ensuring that it is completed on time and within budget.
(6) Managing the preparation and implementation of maintenance schedules
• Ideally, the production department should be responsible for drawing up maintenance schedules in cooperation with the maintenance department, based on the systems it (the production department) has developed for managing its own equipment.
• Annual maintenance work schedules should be drafted for selected key machines only, to enable them to be maintained effectively using the limited financial and labor resources available. The units chosen should be reviewed annually, as their importance may vary with changes in the production schedule, modification of existing equipment or the introduction of new equipment, or as a result of the benefits achieved through good maintenance.
• When drafting a maintenance schedule, it is important to find ways of reducing the overall maintenance burden. Appropriate maintenance intervals should be determined by examining historical records of periodic inspection and repair work, and improvements should be introduced to extend those intervals wherever possible.
• Once completed, a maintenance schedule may still be affected by changes in the production schedule or other factors, and items may well have to be added during its implementation. It will only serve its purpose if fine-tuned in response to these changes. Amendments can be highlighted by using a different color.
• For the monthly maintenance schedule, a card index system should be set up for tasks repeated at fixed intervals, whilst special individual forms are used for other tasks. Weekly and daily progress can then be monitored by using a card rack.
It is important to use visual management techniques for monitoring progress. The cards should first be inserted into an annual maintenance calendar and then allocated successively to monthly maintenance calendars according to the month in which the task is to be carried out. This displays the maintenance schedule visually, and allows progress to be monitored and delays seen at a glance by removing cards as they are completed.
Figures 6.21 illustrate a system of this kind.
In other words, the key priorities are to ensure that the maintenance schedule can be revised easily in response to changes in the production schedule; to reduce administrative paperwork by using cards to record information on completed maintenance tasks; and to incorporate this information into the maintenance standards and use it for MP design.
Figure 6.21 Determining Inspection Frequency (Example)
4.5 Creating and Managing Maintenance Budgets
(1) Maintenance cost categories
For accounting purposes, maintenance costs are treated as a specific item of expenditure, and are generally divided into the subcategories of material costs, labour costs, outsourcing costs and so on. However, in managing the maintenance budget, costs should be classified as indicated below, since this will provide much more valuable information for management purposes (see Figure 6.22).
Classify maintenance costs by:
- Routine maintenance costs
The costs of the labour, materials, etc. required to carry out routine maintenance tasks designed to prevent the equipment from deteriorating, such as cleaning, checking, lubricating and adjusting.
- Equipment inspection costs
The costs of the labour, materials, etc., required to inspect equipment for the purpose of identifying abnormalities or evaluating operational performance.
- Repair costs
The costs of the labour, materials, etc. required to repair and restore equipment.
2 Maintenance method
- BM (breakdown maintenance) costs
- PM (preventive maintenance) costs
- CM (corrective maintenance) costs
- Material costs
This category covers the cost of all materials used for maintenance, such as spare parts, general materials, consumables, lubricants, jigs, tools, etc. It is important to break these costs down in further detail.
- Internal labour costs
This includes not only the labour costs of maintenance staff, but also the relevant labour costs of operators performing Autonomous Maintenance.
- Subcontracting costs
The cost of using subcontractors to do maintenance work.
4 Size of job -e.g. large maintenance projects and small miscellaneous jobs 5 Trade -e.g. mechanical, electrical, plumbing, instrumentation, etc.
(2) Problems in creating and managing the maintenance budget
1 You are not ‘given’ a budget; you have to take it!
Financial investment is needed if equipment performance and efficiency is to be improved in order to reduce overall maintenance costs and increase profits, and the decision on how and where to spend this money is not the responsibility of the finance department alone. Clear policies and plans for the medium and long term should be drawn up, stating what benefits will be achieved by what spending. These plans and policies will then provide an essential foundation for creating a detailed maintenance schedule and a budget framework based on it (see Figure 6.22).
2 This means that each expense needs to be categorized according to its precise purpose, both in the proposed budget and the actual expenditure record, and a special effort must be made to reduce it by implementing improvements with the aim of lowering the overall cost. This must be done even if a special temporary budget has to be set up for the purpose.
3 The individual benefits of each item in the improvement plan must be detailed, and the ROI (return on investment) should be estimated in order to justify the proposal.
4 It is pointless having a plan if it is forgotten or allowed to fall behind. Important plans, such as improvement plans, therefore need to be made traceable by incorporating them into the annual maintenance calendar, clearly indicating the person responsible and the work processes involved.
5 Budgets are not cast in stone
Production conditions change all the time; new improvement requirements emerge, and existing ones change, on a daily basis. If there is neither the budget nor the staff to get these improvements done, then the maintenance situation will not advance. It is important to calculate the expected costs and benefits (i.e. the return on investment), always considering the prevailing business environment, and use this information as a weapon for obtaining approval for the necessary changes to the annual schedule (i.e. the maintenance calendar) and budget, and for removing potential obstacles to implementation.
6 Delays in implementing the plan, or failure to achieve the anticipated benefits, are often due to lack of technical capability during the preparation and implementation phases. Qualified people from relevant departments must be employed from the outset to make the most of the technical information available, from both internal and external sources. It is up to managers to ensure that this takes place.
7 Results must always be evaluated and used for selling the benefits of maintenance, since it generally has too low a profile.
Figure 6.22 Classification of Maintenance Costs
(3) Keys to reducing maintenance costs
It is not going too far to say that all companies have scope for reducing their maintenance costs, to a greater or lesser extent. The focus for cost-cutting will vary in each company, depending on the sector it works in and the equipment it uses, so it is hard to make sweeping generalisations, although VE (value engineering) often proves to be a very useful approach. Maintenance cost reduction is discussed from a general perspective below (see Figures 6.23 and 6.24).
1 Review frequency of periodic servicing
The different sections and components of a machine do not all deteriorate at the same rate, and the intervals for periodic servicing and overhaul are usually determined by the part having the shortest working life. Servicing intervals often become fixed out of habit, to once every 6 months or 10 months, for instance, and must be revised comprehensively from time to time. It is also important to move progressively from time-based maintenance to condition-based maintenance, by introducing equipment diagnostic techniques.
2 Bring subcontracted work in-house
Preventive maintenance tends to account for the largest share of maintenance costs, with outsourced repairs, in particular, representing the principal cost. If this is the case, and there is too great a dependence on subcontracting, then maintenance technology and skills will flow out of the company and it will be unable to build up its own body of preventive maintenance expertise. The key, therefore, is gradually to bring the subcontracted tasks in-house.
3 Review spare parts
Maintenance stores often contain a much larger stock of spare parts than the annual budget would appear to warrant. In some cases, valves, flanges, V-belts and seals are held in stock for as long as two or three years, and some of them deteriorate functionally even before they are used. Even when the stock of spares is controlled by the order-point method, the order points have often been decided several years before and are unsuited to the current situation. It is important to reduce the number of spares held permanently in stock, whilst increasing the number of those bought in as needed.
4 Make effective use of idle equipment
The old throwaway mentality meant that equipment was often discarded and replaced as soon as it began to get a bit long in the tooth, but we now need to be much more prudent about how we consume our natural resources. This means thinking carefully about ways to reuse or recycle equipment, rather than simply throwing it out. For instance, a plant may have a large number of pumps and motors that it no longer uses, but this does not mean they no longer have any value. It is worth exchanging information with other sites to see whether such equipment can be used elsewhere.
5 Reduce loss of energy and other resources
A quick tour of any site will always reveal energy losses of some kind, whether they result from leaking oil, air, steam or water, lights left on all the time, or furnaces or motors left running when not in use. There will also be many instances of wasted resources, such as raw materials being scattered, spilt or damaged.
6 Eliminate equipment losses
Equipment is also the source of considerable financial losses. After an unexpected breakdown, energy losses and yield losses will be incurred until the equipment is fully up and running again, and if a machine’s performance drops, it may start to produce quality defects. Such financial losses can be greatly reduced by introducing TPM and maximising equipment efficiency.
4.6 Keeping and Using Maintenance Records
Production and maintenance activities produce a vast amount of highly diverse information relating to maintenance management and maintenance technology. Recording all of this would be a daunting task, and unnecessary. In the end, information is used by people, so the aims of the maintenance records should be made clear, stating why the information is being gathered, what is being monitored, and how the information is to be used. The records kept should suit the purposes of the site that is keeping them.
4.6.1 Types of maintenance record and their objectives
Maintenance is implemented in a variety of ways, depending on the particular site’s policies and the level to which it is managed. Likewise, there are various different methods of recording maintenance data, and there is no single method that could be used in any situation. However, Table 6.7 shows the types of maintenance record considered to be the basic minimum in a typical factory, indicating the relevant maintenance function and objective for each record.
Table 6.7 Types of Maintenance Record and their Objectives
Figure 6.25 PDCA Flowchart for Data Recording
Figure 6.26 Failure and Maintenance Information (from a typical factory)
4.7 Main Activities in Building an Effective Maintenance System
The activities involved in creating an Effective Maintenance system can be broadly divided into the following two categories:
(1) Working with Autonomous Maintenance to develop strategies for reducing the frequency of failures while preventing their recurrence, at the same time as establishing preventive maintenance based on a maintenance calendar.
(2) Strengthening and enhancing various maintenance management activities in order to support the preventive maintenance system
Figure 6.28 The Development of Effective Maintenance (8-pillar)
Equipment breaks down every day and lowers production OEE, to avoid or reduce (eliminate) …