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close this bookProductivity and Quality Management: A Modular Programme - Part II: High Potential Productivity and Quality Improvement Areas (APO - ILO, 1997, 630 p.)
close this folderMODULE 21: PRODUCTIVITY BY MAINTENANCE
close this folderUNIT 4: Preparing for implementation
View the document(introduction...)
View the document4.1 Maintenance planning
View the document4.2 Equipment documentation
View the document4.3 Spare parts and stores
View the document4.4 Corporate policy for maintenance training
View the document4.5 Exercise on maintenance organization and information flow

(introduction...)

UNIT 4: LEARNING OBJECTIVES

Once you have learnt this unit you will be able to:

1. Understand and apply maintenance planning methods.

2. Set up a documentation system for equipment, spare parts and stores.

3. Formulate maintenance policies, design a maintenance system and train a maintenance specialist.

4.1 Maintenance planning

The planning of maintenance work concerns daily maintenance, the repair schedule, preventive and design-out maintenance, periodic overhauls, planned replacements and the activities of the central workshops. In this section we will detail the planning of preventive maintenance and lubrication and also the planning of overhauls and major repairs.

Planning of preventive maintenance

The preventive maintenance file contains all the information necessary for preventive maintenance work. This information includes the work study (work specifications), details of the machine to be inspected, job planning, inspection schedules and checklists. A distinction is made between the following types of information:

- job instructions - the preventive maintenance card;
- programming of preventive maintenance - work programming;
- scheduling of preventive maintenance jobs - workload planning;
- inspection of the work.

The preventive maintenance card separates the work into mechanical, electrical and instrumentation work. A card is made for each machine, assembly or sub-assembly. Instructions are given for each periodicity, starting with the highest one. These instructions should be clear, precise and simple.

Based on the preventive maintenance programme for each machine, detailed planning will be undertaken for all the machines. Preventive maintenance planning will take into consideration the time necessary to carry out all the jobs for each sub-assembly indicated in the programme. It will also consider the periodicity of the inspections.

Planning of lubrication

The lubrication file contains all the information necessary for carrying out lubrication, including work specifications and lubricating points, planning and inspection. A distinction should be made between the following elements:

- work instructions - the lubrication card;
- lubrication planning - work programming;
- the lubrication workload schedule - workload planning.

Planning is carried out for lubrication which exceeds two weeks. It is based on the lubrication programme and is in line with preventive maintenance planning, because most lubrication activities which exceed two weeks coincide with periodic maintenance.

Planning of overhauls and major repairs

The various operations in maintenance work can consist of a number of complex tasks. This is especially the case for overhauls and major repairs. Planning must respect a particular sequence and interdependency. This means that certain tasks are consecutive, while others can be done simultaneously. Several methods exist for the planning of overhauls and repairs, including the PERT method (programme evaluation and review technique). The methods are based on calculating the critical path of all tasks to be executed; this can be done very easily today by using existing microcomputer programmes.

4.2 Equipment documentation

The objectives of technical documentation

The lack of equipment documentation is a major problem faced by maintenance services in production plants. Equipment documentation is necessary to ensure maintenance management, repair work, manufacture of spare parts, rapid troubleshooting, work safety, the correct selection and management of spare parts and efficient staff training. Unfortunately, when purchasing production equipment, technical documentation is frequently neglected by both supplier and customer.

Complete documentation is expensive. For a new factory it can vary between 8 and 22 per cent of the value of the equipment. In order to lighten expenses for existing plants, full documentation should only be prepared for priority equipment. In any case, investment in setting up or improving technical documentation will only be justified if the documentation is used efficiently. For this, the documents must be updated regularly and dispatched judiciously.

Content of equipment documentation

Technical documentation can be divided into three types:

- study and engineering;
- construction and start-up;
- exploitation.

We have paid most attention to the third type, which is vital for the efficient running of the factory, because most of the documents concerning engineering, construction and start-up are little used once the factory is in production.

Equipment documentation is classified in four different types of file, established by zone, department or production line: these are the general file, the machine files, the utilities file, and the standard files. All the documents should be presented in hard-cover A4 binders. The different headings are separated by numbered insertions so that each heading is easily accessible.

a) General file

This file consists of:

- technical specifications for the installation;

- flow sheets showing the machines and apparatus, and information concerning raw materials, consumption of fluids, etc.; the plant layout and section drawings of installations showing clearly the connections between the different machines;

- operation and service instructions.

In order to obtain an overall view of the equipment belonging to the installation, an ‘inventory of machines’ will be set up including the machines, apparatus and important accessories.

b) Machine files

In the machine files a distinction is made between the important/complex machines and the simple ones. The file of an important or complex machine is composed of eight headings under which the equipment documentation is classified. The same sort of classification is used for simpler machines and equipment but the content will be reduced.

The different headings comprise the following documents, separated by numbered insertions:

1. Technical documentation: machine record card/layout drawings/description of functioning

2. Installation and start-up: foundations and installation/transport and handling/instructions for assembling/commissioning

3. Instructions for operation: safety instructions/operation/instructions for tuning/troubleshooting

4. Service instructions: maintenance/lubrication

5. Drawings and nomenclature: mechanical/electrical and automation/instrumentation/hydraulic/pneumatic and other fluids

6. Recommended spare parts

7. Prospects and catalogues

8. Control certificates and commissioning reports

c) Utilities file

The utilities file deals with the distribution network of energy and fluids, such as electricity, compressed air, water, steam, and gas. The drawings and documents dealing with machines which produce energy and fluids can be found in the appropriate machine files. The utilities file also contains eight headings, which are:

1. Technical characteristics
2. Description of the installation
3. Exploitation manual for the installation
4. Maintenance
5. Prospectus and service manuals for apparatus and devices
6. List of recommended spare parts
7. Drawings and diagrams
8. Control certificates and commissioning reports

d) Standard files

Documentation for standard apparatus and accessories (valves, motors, pumps, measuring devices, etc.) for machines or installations, is classified in the standard files. There are three types of standard file: mechanical, electric/automation and instrumentation. These files also contain the same eight headings as above, but the content is simpler.

Management of equipment documentation

The coding structure of equipment documentation corresponds to different sections of the factory; a code is given to each machine, assembly, sub-assembly and apparatus. This permits the allocation of maintenance expenditure to each machine and makes it possible to follow up interventions which have been carried out. It is an invaluable tool in maintenance management. This coding is also used in filing and administering the technical documentation.

The room in which technical documentation is stored should be dust-free and dark so that the documents do not deteriorate. Drawings should be stored in drawers, according to codification number and size (A0 to A4). The machine files, standard files and utilities files should be stored in metal cabinets, according to the file number. Catalogues of standard and commercial parts and products will also be stored in metal cabinets. Filing will be carried out alphabetically.

Each modification, however small, must be recorded immediately on the original documents and made known to the users. This updating is important because it mainly concerns the drawings (electrical, mechanical, etc.). It must be carried out by the methods section together with the drawing section of the CMPO. Each modified drawing will carry a new index. The updates are also noted on a sheet in each machine file. In this way it is possible to see at any time if the plan or document in one’s possession is the latest and most up-to-date version.

Basic terms of reference for equipment documentation

The terms of reference for documentation to be supplied by the manufacturer should be available. These are added to the terms of reference that deal with general and detailed conditions of purchase.

The objectives of the terms of reference are:

- to determine which documents, drawings and diagrams are to be delivered by the supplier;

- to define the standard format and other requirements which the above documents should satisfy;

- to define the form of presentation in order to obtain uniform documentation which is easy to classify and consult;

- to define the delivery conditions for documentation (where, when, how, number of examples, originals, etc.);

- to determine the responsibilities of the supplier and to fix penalties if the contract is not fulfilled.

Improvement actions in the plant

At plant level, the following short-term improvement actions are recommended:

- centralize all technical documentation in one area of the plant;

- code and classify the documentation, create a system for updating and dispatching;

- specify priority machines with a high risk of production bottlenecks and make up detailed machine files for them;

- establish standard terms of reference for technical documentation which must be imposed on equipment suppliers.

4.3 Spare parts and stores

The following common problems are typical of spare-parts management:

- a wide variety of equipment manufacturers and little effort made to standardize machinery and components, resulting in a large investment in spare-parts stock;

- poor selection of spares to be stored;

- incorrect designation of spare parts;

- lack of a uniform in-plant codification of parts;

- inefficient or non-existent stock management, due to a lack of systems or a lack of information;

- lengthy reordering delays due to internal delays in the company, delivery delays, delays in payment, customs delays;

- lack of hard currency in some countries for imported spare parts, which obliges plant management to reduce its stock:

- random allocation of import quotas in certain countries;

- poor storage due to inadequate facilities;

- poor knowledge of stock.

In addition to the above problems, detailed contractual clauses concerning spare parts are often missing or unclear when purchasing equipment. Specific tender documents for spare parts rarely exist.

Techniques for reconditioning spare parts (protective coating through welding, metalization, application of antifriction metal, adhesives, Metalloc system, etc.) are little known and in many countries almost no effort has been made to develop them. Nevertheless, they represent a cheap way to make up for the lack of spare parts. Finally, very little action has been taken in the field of specialist training for the selection, coding and designation of parts and for stock management.

Selection of spare parts to be kept in stock

The stock in a maintenance store can be divided into three types of article:

- specific parts of an installation, machine or device. These are manufactured specially for the equipment and are not interchangeable with parts from another make (for instance machine frames, valve-lovers, spiral gears, switch-contacts, piston-rings, connecting-rods);

- standard parts which correspond to international standards and/or which are interchangeable with parts from another make. The manufacturer of the parts is not necessarily the manufacturer of the equipment on which they are installed. Examples of standard parts are bearings, 0-rings, lip-seals, fuses, cocks and fittings, roller-chains, V-belts, etc.;

- maintenance consumables and current store items which are generally found on the market. These include sheetmetal, iron castings, nuts and bolts, pipes, building materials, sealing compounds, cleaning products, rags, glues, lubricants, grinding paste, etc.

The selection of parts to be stored is based on a study of the equipment components and related factors, including:

- parts subject to wear;

- parts which rarely wear out but which must be in good condition for the machine to function;

- stress on the equipment and its components in relation to the degree of utilization;

- the lifetime of the equipment;

- the technical level of operators and maintenance personnel;

- the motivation of personnel;

- the management and care of production equipment;

- the general organization of the company and of maintenance in particular.

Stock levels depend on the availability of a rational stock management system, thus allowing a strict follow up of consumption. If this system does not exist from the very beginning, initial supplies should be increased.

Parts designation and codification

Without a uniform and common language, it is impossible to centralize spare-parts management and stores for different production areas. Therefore it is vital to set up a single designation and codification system for spare parts and current store items. Correct designation is indispensable in order to:

- avoid stocking identical parts under a different name, in different places in the store and consequently to avoid ‘false’ stock-outs (an item is thought to be out of stock but the same part is available under a different label);

- ensure easy filing in the purchasing department and the stock management section;

- develop a common language between users, purchasers and suppliers;

- allow the supply of standard parts from the world market and not only from one supplier according to a standard (international, national, company or in-house) for parts.

A coding system has to meet the following requirements:

- a code number must correspond to one item only;

- an item must correspond to one code number only;

- a code number must be final. A change of code number is a constant source of confusion and should be avoided;

- the code number must be logical, i.e., given according to a system reflecting the main characteristics of the item which has to be coded.

A system which generally provides good results in industry is based on codification according to the nature of the spare parts. It starts with a broad classification of products into ten classes (from 0 to 9). The classes are then divided into families, sub-families, groups and subgroups. A code number of eight figures is enough even for very large stores.

In order to proceed with codification, a grid should be set up, adapted to the equipment in the company. This must be done by the spare-parts management and stores service, assisted by a methods section and/or the technicians in charge of job preparation.

Spare-parts management

The function of stock management (or stock administration) is to ensure the availability of spare parts according to demand. The basic parameters of stock management are monthly consumption, unit price, delivery time, reordering level, minimum stock level and maximum stock level. When considering reordering quantity and frequency rational stock management means that the total of purchase price, acquisition cost and owner costs is kept to a minimum, with:

- acquisition cost: all administration costs in connection with purchasing

- owner costs: all costs resulting from stock composition and conservation (interest loss on invested capital, storage costs, personnel costs, distribution and conservation costs, etc.)

The system chosen will depend on the nature of the item, and its average consumption. In general two main categories can be established:

- consumables and non-durable items, current store items, standard parts, certain specific parts. These items are used often, their lifetime is limited and they are subject to wear. They are called fast movers;

- items which are rarely used, but which must be kept in stock, in case of unexpected breakdown, incident or wear. A prolonged stoppage of the machine can occur if they are not in stock. They are called ‘buffer parts’ or ‘slow movers’.

It is evident that stock in the first category will have a fast turnover, whereas stock in the second category will be ‘resting’. The criterion for classifying an item is its monthly consumption. If consumption exceeds 25 per cent of stock, then an item will be listed as a fast mover; if less than or equal to 25 per cent it will be listed as a slow mover.

In order to avoid stock-outs due to a longer delivery delay then expected or due to accelerated consumption, a ‘safety stock’ or ‘minimum stock’ is determined. This stock is expensive because it is permanent, it takes up precious storage space, it uses capital and it causes owner costs (conservation, personnel, etc.).

Management of fast movers is mainly based on the quantity to be ordered, which takes into account the utilitarian price (Pu) of the item (unit price increased by transport and handling costs, etc.), the interest on invested capital (i) and sundry costs (d) (storing, personnel, etc. expressed as a percentage of average stock).

The economic quantity is calculated according to Wilson’s formula

where

Ma = average monthly consumption
Q = quantity per order acquisition cost per item

and

CA = the acquisition cost per item

This quantity should be tentatively considered as the correct quantity to store. It is rounded up to the next packing quantity or adjusted in relation to projected maintenance events such as big repairs or important overhauls.

It must be emphasized that the use of formulae for reordering should only serve as a guideline. They help the decision maker to take all the parameters into consideration but a considerable number cannot be translated into formulae. This is why permanent follow up and updating of the files are required.

Slow movers are not supposed to be subject to much wear. Therefore, it is the safety stock which is at stake if unforeseen breakdowns occur. In order to determine the quantity of slow movers to store, answers must be provided to two questions:

- what is the impact of a broken part on production?
- what are the possibilities of local repair or reconditioning of the part?

The quantity to be kept in stock can be decided on the basis of this information and taking into account the price of the items, as well as the type of reordering. In some cases zero stock may be acceptable (e.g. a repaired part can be used if the frequency of incidents permits it).

Different types of reordering are possible, both for slow movers and for fast movers:

- reordering based on a reordering level: each time stock reaches the level which equals the sum of consumption during the internal reordering period + consumption during the delivery period + the minimum stock, a quantity calculated by Wilson’s formula is reordered;

- periodical reordering: a consequence of reordering based on the reordering level is that orders are placed at variable dates. The disadvantage of this is that each item must be considered separately. Grouping would reduce the number of orders. The two main criteria for this grouping are the supplier and the geographical location;

- reordering in the case of low consumption: when consumption becomes very low, i.e., less than one unit per delivery period, the quantity to be stocked is calculated according to consumption during the time between two deliveries;

- reordering by contract: this is more a purchasing technique than a method of stock management. It consists of a contract with a supplier which specifies the quantity to be supplied over a certain period of time. The contract details all the purchasing conditions, particularly price and delivery period.

Regular stock analysis permits the tuning of spare parts management and should be an element of general policy. It determines the parts which need particular attention and which directly influence the efficiency of spare-parts management.

The process of stock analysis consists of putting the items in decreasing order of value (unit price). Subsequently a graph is drawn up: in abscissa, the cumulated items in the same order as above, and in ordinate the corresponding cumulated values (this method is called ABC-analysis).

The conclusion reached is that a major part of the capital invested is tied up in a small number of items. Studies aimed at reducing stocks of these items will make a considerable financial impact. This in turn will optimize stock management.

Storage systems

The following factors are essential to ensure optimal storage:

- spacious premises with well-designed storage systems, allowing easy access;

- suitable handling equipment in sufficient quantity;

- suitable shelves, bins, racks and other storage facilities;

- order and cleanliness;

- methods for conservation of parts (protection against dust, rust and humidity, suitable conditions for storing perishables).

From the organizational point of view, a centralized spare-parts management and stores service produces the best results. Auxiliary (buffer) stores in production areas are possible, but the stored items are then considered as being consumed.

4.4 Corporate policy for maintenance training

Objectives and prerequisites for maintenance training

The principal objectives of maintenance training are as follows:

- remedying as quickly as possible the lack of qualified personnel;

- adapting employees to their work;

- mastering imported technology;

- adapting the workforce to technological change;

- increasing productivity;

- bridging the gap between industry needs and academic training;

- keeping up with rapid changes in industrial society.

The following measures have to be taken before a training programme is launched:

- organization of maintenance in the company (organization chart, job descriptions);

- assessment of training needs;

- formulation of a training policy;

- planning of recruitment and training, with regard to the need for skilled workers;

- appointment of a head of training for follow up, checking and evaluation of results;

- administration of training and recruitment.

Assessment of training needs

Training needs are assessed on the basis of an in-depth analysis of maintenance practice in the company. In relation to the present inventory of production equipment, actual and future training needs are defined taking into account production programmes (load on the machines), reserves (margin to cover unexpected breakdown) and shut-downs for maintenance reasons. A maintenance policy for this production equipment, in relation to safety, price, and availability, will make it possible to estimate the amount of scheduled and unscheduled work. The time required can then be calculated from the maintenance programmes and periodicities for scheduled work and on estimates for unscheduled work. In this way the workload of the maintenance department can be predicted. The organization of work can then be defined including the organization chart, the information flow, management and quality control aspects. This will indicate the need for direct and indirect personnel, installations and spare parts. Detailed staffing tables can then be set up.

A comparison should be made between existing staff capacity and projected personnel needs. This will show the detailed training needs for workers (direct personnel) and for supervisors and engineers (indirect personnel). Training programmes should be drawn up on the basis of job descriptions and a vocational training analysis, including retraining and upgrading.

Development of appropriate training methods

a) Management training

Training of engineers and maintenance managers covers two fields: maintenance techniques and maintenance management. For technical training, the best method is to organize short study tours to machine manufacturers, complemented by on-the-job training during plant construction or by a specialized technical assistance programme. Training in maintenance management should be carried out through specialized upgrading seminars complemented by short-term practical training in selected plants.

b) Supervisory training

Team leaders Part of the training of team leaders can be carried out in a training centre or institute; here they receive theoretical training which brings them up to the technical level needed. Team leaders are often recruited amongst young qualified workers and are selected for their intelligence, their ability to explain and control a group. They are chosen not only for their professional qualities but for their human qualities as well. After an appropriate period of job experience and having obtained the necessary qualifications, they will become team leaders, responsible for four or five workers.

Technicians and foremen The best qualification for foremen is the accumulation of years of professional experience. The foreman is the keystone of a maintenance department. If foremen are needed urgently, then intensive training can be given to thoroughly experienced workers. On-the-job training has produced excellent results in the past.

c) Training of workers

Training programmes for skilled workers should ensure that the trainee learns not only techniques but also work habits. To achieve this, workers should be given more responsibilities and skills. On-the-job training is most appropriate for workers on the shop floor. They acquire practical skills by trial and error and accumulate a certain amount of theoretical knowledge.

As previously mentioned, on-the-job training for maintenance workers during the construction of a plant is indispensable. One efficient solution is to integrate maintenance workers into the construction teams. The builder is responsible for their work but their activities are monitored by the head of training in the company.

Apprenticeship programmes should be promoted for young workers. Experience has proved that apprenticeship is one of the most efficient methods for training new maintenance workers. Small groups composed of a foreman, a qualified worker and an apprentice have produced excellent results.

4.5 Exercise on maintenance organization and information flow

The exercise takes as an example a brewery producing 100.000 hi/year. The brewery has the following main sections:

- storage tanks for raw materials (a lot of stainless steel, piping, pumps, valves, some instrumentation)

- brewery

- bottling and storage of final products

- utilities (steam generation - refrigerating network - compressed air - carbonic acid - gas - water and related treatment - fuel)

The brewery and utilities sections work on a round-the-clock basis. The bottling section works two shifts five days a week. The total workforce is 100.

The following elements should be considered in the organization of maintenance:

- maintenance of rolling-stock (lorries, vehicles) is not done by the plant;

- the workshop is equipped with 1 lathe, 1 milling machine, a table-grinder, some work benches and welding equipment;

- all painting, heavy metallic construction and piping, woodworking and heavy jobs are subcontracted;

- the spare parts store is open 8 hours per day, 5 days per week. Access to the store outside these periods is assured by the shift boss;

- maintenance staff are on duty during the night and at weekends.

It should be pointed out that many small problems arise in the bottling section. This section needs the permanent presence of maintenance personnel, especially mechanics.

The exercise consists of carrying out a restructuring study on the maintenance department. It has been decided that a central maintenance structure should be installed at the same level as the production department. The following workers will be kept: one electro-mechanical foreman, two electro-mechanical qualified workers level 3, two mechanical qualified workers level 2, one electrical qualified worker level 2, one storekeeper and one specialized welder.

Questions

1. Design a simple but efficient maintenance organization chart for the plant.

2. Set up a manning table for the maintenance department; the eight workers listed above should be kept and additional staff should bring the maintenance workforce up to a maximum of 25.

3. Devise a data-flow circuit for preventive maintenance work and for planned corrective work. The data flow should include a list of forms and the number of copies to ensure correct data transmission.

Please compare your solutions to those given in Annex I to this unit.

ANNEX I

The brewery

a) Organization chart and staffing table

Various organization charts are possible but the one presented below has produced very good results.


Figure

MSI

:

Maintenance Superintendent

CMPO

:

Control Maintenance Planning Office

ST

:

Store

UTL

:

Utilities

INT

:

Interventions

WS

:

Workshop

BOTT

:

Bottling section

PM

:

Preventive M

CM

:

Corrective M

Several staffing tables could be set up. The point is to ensure that all maintenance tasks are carried out with a minimum of personnel.

The following table has produced excellent results.


ENG

P

F

M

E

EM

SK

LMO

W

TOT

MSI

1









1

CMPO


1








1

INT



1







1

CM




4

4





8

PM




2

1





3

BOTT




2






2

WS








1

1

2

ST







2



2

UTL






4




4

TOTAL

1

1

1

8

5

4

2

1

1

24

ENG: Engineer
P: Preparator
F: Foreman
M: Mechanic
E: Electric
EM: Electro-mechanic
SK: Store keeper
LMO: Lathe and milling machine operator
W: Welder

The above functions/personnel will deal with following tasks:

MSI: maintenance superintendent - engineer (BSc) or higher technician

- maintenance management
- supervision of stores
- supervision of UTL-crews
- stock management

CMPO: central maintenance planning office - job preparation

- maintenance methods
- job preparation
- selection of spare parts to be kept in stock
- work programming

INT: interventions headed by a foreman

- supervision of crews
- work-scheduling/follow up of work-in-progress
- quality control of finished work

CM: corrective maintenance crew - working in shifts (3 × 8 hrs + 1 in rest) - composed of four qualified mechanics level 2 (one per shift) and four qualified electricians level 2 (one per shift) - in charge of repairs and troubleshooting - also in charge of cleaning and some greasing work during the night shift. The crews deal with the whole plant except the bottling section (mechanics) and utilities section (mechanics and electricians).

PM: preventive maintenance crew - day-crew (8 hrs/day) composed of two qualified mechanics level 2 and one qualified electrician level 2. In charge of execution of all preventive work, inspection rounds and lubrication. This crew deals with the whole plant including the bottling section, but with the exception of utilities.

BOTT: permanent presence of one mechanic in two shifts for corrective maintenance, lubrication and cleaning.

WS: the workshop has one lathe and milling-machine operator and one specialized welder (for stainless steel welding).

ST: The store has one store-keeper in two shifts - during the night and at weekends the store can be opened by one of the qualified workers on shift - store-keepers are in charge of supplying spare parts, cleaning, and keeping records (inventory).

UTL: Utilities are operated and maintained (preventive and corrective) by one qualified electro-mechanic level 3 in three shifts.

b) Information flow

A job request is issued for every job except work foreseen in the preventive maintenance and lubrication programme or emergency work. The job request is sent to the CMPO, which registers it. A short analysis is done: if the work is complex, a work-file is opened which contains the job request, drawings, schemes and any other instructions. This information will allow for job preparation. For a simple job or after preparation of a complex job, a job order is issued showing when the work can be carried out (all resources available).

The CMPO enters the work into the long-term plan (programming). On the basis of this, the CMPO transmits the work-file (complex work) or job order alone (simple work) at the right moment to the supervisor of interventions who plans the workload and distributes the work to the teams. Emergencies are communicated by phone to the supervisor who will issue a job order after the work has been done.

If the job cannot be done there are two possibilities: if the problem is temporary a job order is issued which then waits until all resources are available; if it is definitely not possible to do the work then everyone concerned must be informed.

A data-processing circuit for this exercise is shown below (job execution, figure A1). In this circuit the number of copies of each form is indicated. In order to guarantee good information flow to the maintenance manager, the foreman or workers complete a job report at the end of each shift.


Figure A1: Job execution

A similar information flow is applicable to the scheduling of preventive maintenance. In this case, work originates in the preventive programme, which differentiates between work with a high frequency (periodicity less than 2 weeks) and work with a low frequency (periodicity more than 2 weeks), as shown in figure A2.


Figure A2: Preventive maintenance

For high frequency work, the foreman will automatically include the high frequency jobs in the workload planning of the teams. The list of jobs and their periodicity is compiled only once by the CMPO (central maintenance planning office). Copies of the preventive maintenance cards which contain the work instructions and specifications are lodged with the foreman of the intervention section. For scheduling the jobs, the CMPO sends a job order to the foreman with a cumulative list of all relevant preventive maintenance cards/tasks. After the job has been done and inspected, the completed job order will follow the normal circuit described above.

Regarding low frequency work, the CMPO will make a job order in conformity with the preventive maintenance programme. The corresponding preventive maintenance cards will be added and a work-file containing all relevant information will be opened. The work is entered in the long-term programme. The file is transmitted to the foreman, who enters it in the workload planning. Execution and further data processing is carried out according to the circuit. After preventive maintenance has been carried out, the maintenance worker will make a job report. A data-processing circuit for preventive maintenance is presented below in figures A3 and A4.


Figure A3: Simplified circuit of job requests and job orders


Figure A4: Simplified data-processing circuit for spare parts

Inspections are included in the foreman’s workload planning or are done by the preparator from the CMPO. An inspection report is made after each inspection. This report is a form which should already contain all the predetermined points in a checklist where the items have to be ticked.

ANNEX II

Answers to questions

1. A maintenance management plan should cover the following topics:

- the hierarchical position of maintenance in the company organization chart;

- the development of human resources in maintenance;

- the introduction of an accounting system which details maintenance expenditure per cost centre and per machine;

- the setting up of a separate maintenance budget;

- the acquisition and renewal of equipment (choice of technology, definition of reliability and maintainability specifications in the design, terms of reference, participation of maintenance specialists during negotiations, introduction of the life-cycle cost approach, taking into account the indirect costs);

- the structure of maintenance: centralized, decentralized or mixed;

- computer-assisted maintenance (technical) and computerized maintenance management systems;

- subcontracting of maintenance work;

- the definition of a maintenance concept;

- the relation with the QC department;

- the safety of personnel and safety in general;

- the protection of the environment.

2. An important part of the maintenance management plan is the definition of a maintenance concept, which in fact means choosing a maintenance form for each machine depending on company priorities in terms of safety, production, quality, cost and protection of the environment. The use of the following techniques can be considered:

- Failure mode effects and criticality analysis (FMECA) which deals with the study of failure mechanisms of components. The effects of possible failures are analysed in relation to the function and performance of each component. They are divided into various categories: catastrophic, complete or partial loss of function, no effect. A criticality index for each failure mode is obtained by calculating the product of the following ratings:

- probability of each failure mode occurring;

- seriousness of the failure;

- difficulty of detecting the failure in advance.

- System-reliability analysis. This analysis is based on the FMECA for components and their influence on the system, and on maintainability considerations;

- Fault tree analysis (FTA) is a risk analysis based on the study of failures or malfunctions which can lead to catastrophic failure. A risk of occurrence is given for each of these events which, through a fault tree, finally gives the catastrophic failure risk:

- Hazard and operability study (HAZOP) is the study of possible failures and their effect on the operability of an item (component or system). This study is carried out during the design stage as well as continuously during operation;

- ABC analysis (Pareto’s law): production machines and utilities are grouped in three classes depending on the importance of the effect of failures or malfunctions. The degree of importance is given by an enterprise-specific priority rate in relation to safety, production, quality and protection of the environment. Failures on 20 per cent of the machines will be responsible for about 80 per cent of critical effects.

A maintenance concept (policy) can be defined in terms of the proportions between the various maintenance forms (periodic, condition-based, corrective or design-out maintenance), which must be applied to each component or system.

Periodicities for components or sub-systems must then be grouped into packages. This will lead to maintenance programmes which should be linked to maintenance levels. For each level, the maintenance tasks can then be defined in order to assess the necessary human and material resources.

Regular evaluation must be carried out of implementation of the maintenance concept and the effect on equipment. This will allow a tuning of the maintenance programme and feedback of information.

3. At plant level, the following actions for improvement are recommended:

a) Short term

- centralize all technical documentation in one area of the plant;

- codify and classify the documentation, create a system for updating and dispatching;

- specify priority machines with a high risk of production bottlenecks and make up detailed machine files for them;

- establish standard terms of reference for technical documentation which must be imposed on equipment suppliers.

b) Medium and long term

- train personnel in the preparation of machine files and in the administration of technical documentation;

- gradually complete the technical documentation for machines other than priority ones, according to their importance for safety, reliability and production;

- assemble workshop drawings for the manufacture of spare parts, in particular, from manufacturers that are no longer making the parts.