Reliability, Risk and Safety: Theory and Applications – Briš,Guedes Soares & Martorell (eds)

© 2010 Taylor & Francis Group, London, ISBN 978-0-415-55509-8

A new maintenance management model expressed in UML

M.A. López Campos, J.F. Gómez Fernández & V. González DíazDepartment of Industrial Management, School of Engineering, University of Seville, Spain.

A. Crespo MárquezIndustrial Management School of Engineering, University of Seville, Spain

ABSTRACT: This article shows part of the process of designing and modeling a new maintenance managementmodel completely aligned to the quality management standard ISO 9001:2008 and expressed using the UnifiedModeling Language (UML); the features of this modeling language gives the possibility of easily integrate themaintenance process into the general information system of an organization and to create a flexible structureto adapt it to new necessities. This article begins describing the suggested new maintenance model and themethodology used to design it; next are exposed some important concepts about processes modeling and thensome of the modeled diagrams are presented: the general architecture, the goals tree diagram, an specific process(Control & Improvement) and a state diagram for the Maintenance Work Order. This paper finishes with theconclusions and the references used during the research.

1 INTRODUCTION

Maintenance has been experiencing a slow but con-stant evolution across the years, from the formerconcept of “necessary evil” up to being consideredan integral function to the company and a way ofcompetitive advantage.

Since approximately 3 decades, companies realizedthat if they wanted to manage maintenance ade-quately it would be necessary to include it in thegeneral scheme of the organization and to manage itin interaction with other functions (Pintelon, 1992).

In this way implanting a high-quality model to drivemaintenance activities, embedded in the general man-agement system of the organization has become aresearch topic and a fundamental question to reach theeffectiveness and efficiency of maintenance manage-ment and to fulfil enterprise objectives (Prasad, et al.2006).

On the other hand it is known that for a significantnumber of organizations every activity or importantaction realised has its reflection on its information sys-tem; it means that the enterprise information system isa basic element to consider for the implementation ofa maintenance management system. In fact, the mostdesirable situation is the complete integration of themaintenance management operations into the generalinformation system (Vanneste, 1995, p.248).

To deal with the mentioned integration, this inves-tigation proposes the uses of the BPM (BusinessProcess Management) methodology, which aim is toimprove the efficiency through the management ofbusiness process that are modelled, automatized, inte-grated, controlled and continuously optimized (Object

Management Group, 2008). This involves managingchange in a complete processes life cycle.

Using BPM methodology it would be possible mod-eling a particular maintenance management processand afterwards “connect” this model with a generalinformation system. In this way, it would be createda flexible management process that if it needs to bechanged to adapt its activities to new necessities, itwill be quickly and even automatically modified intothe enterprise information system (Framiñan, 2007).

This article shows part of the results obtained in theprocess of designing a new maintenance managementmodel (MMM), completely aligned to the quality man-agement standard ISO 9001:2008 and also expressedusing UML.

2 MAINTENANCE MANAGEMENT MODELS

In the historical development of maintenance, diverseauthors have proposed what they consider the bestpractices, steps, sequences of activities or models tomanage this function. To begin with this investigationit was done a bibliographical search covering the analy-sis of some different maintenance management modelsdeveloped since January 1990 until February 2008.

In this analysis were considered the following mod-els: Pintelon and Van Wassenhove (1990), Pintelonand Gelders (1992), Vanneste and Wassenhove (1995),Campbell (1995), Riis, et al. (1997), Kelly and Harris(1997), Wireman (1998), Duffuaa (2000), Hassanain,et al. (2001), Campbell (2001),Tsang (2002), Waeyen-bergh and Pintelon (2002), Murthy, et al. (2002),Cholasuke, et al. (2004), Abudayyeh, et al. (2005),

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Figure 1. Maintenance management model proposed.

Pramod, et al. (2006), Prasad, et al. (2006), Kelly(2006), Tam, et al. (2007), Soderholm, et al. (2007)and Crespo (2007).

A special mention is for the Publicly AvailableSpecification PAS 55, published in April 2004 by theBritish Standards Institution (BSI) which covers therequirements for good asset management. The modelappearing in this standard was also considered for theaccomplishment of this investigation.

From the analysis of the mentioned maintenancemodels (comparing them between them and withthe ISO 9001:2008) were identified the elementsand desirable ccharacteristics for a new, modern andefficient MMM. These elements are: input-outputprocesses approach, clear methodology of applica-tion, generation of documents and records, objec-tives entailment, incorporation of support technolo-gies, orientation to operate in computer maintenancemanagement systems (CMMS), flexibility to adoptmodern technologies (e-maintenance, expert systems,etc), management of material, human and informa-tion resources, focus on the constant improvement,cyclical, among others.

All these elements were considered for designingthe new MMM. In addition it is important to mentionthat the model proposed in this article results fromits real life application, improving maintenance man-agement schemes in several Spanish companies. Thismeans that an initial validation of the model comesfrom its practical origin.

Another interesting observation from the real lifeexperience is: although some of the ERP that currentlyexists in the market have maintenance modules, thereare several functions that can be still added to improvethe maintenance management.

This proposed new MMM includes those par-ticular functions as novel specific techniques for

the maintenance performance. These techniques aredescribed (using use case diagrams, sequence dia-grams, object diagrams and other artifacts) in the moreprofound levels of the new MMM, although in thispaper we do not refer to them in detail.

3 NEW MAINTENANCE MANAGEMENTMODEL PROPOSED

An important characteristic of the proposed newMMM is its relationship with the ISO standard9001:2008. This standard is chosen since it is theinternational reference for any quality managementsystem, which turns into a generic guide for a pro-cess operation in which fulfillment with requirementsshould be demonstrated, such as the case of the main-tenance function. In the same way, PAS 55 offersvaluable information about the maintenance manage-ment process. The general operation of the new MMMis presented in Fig. 1.

The model begins and finishes with the require-ments and satisfaction of the interested parts, herecalled stakeholders using the concept proposed bySoderholm, et al. (2007) and that is in line with theexpressed by the ISO 9004:2008 standard. Also thismodel is designed to be efficiently used across theorganization levels (reminding Pintelon and Gelders(1992) who proposed a model to be executed in threeorganizational activity levels).

This model is made up of four modules or macro-processes, each one containing inside several pro-cesses that are specified in sub-processes and tasks.The four macro-processes are Planning, Support,Maintenance Execution and Control & Improvement.The Plannig macro-process is conformed by three pro-cesses: Long term planning, medium term and short

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term. The Support processes are: Human resourcesmanagement, Spare parts and materials management,Infrastructure management and Information manage-ment. The Control & Improvement macro-process iscomposed by Measurement &Assessment process andby Improvement process.

It is to be noted that planning (long term) entailsthe top Direction of Maintenance. The medium lev-els perform the support processes and control themaintenance execution. The level that executes main-tenance also generates data to be used in the continualimprovement of the maintenance function.

In the same way, the structure of this model makespossible the existence of a link among the maintenancefunction and the other organizational functions.

Into the model proposed, each one of the processes(planning, support processes, maintenance executionand control and improvement) is defined by UMLdiagrams using the “Eriksson-Penker Business Exten-sions” that indicate the sequence of activities for theexecution of every stage.

Regarding information standards, there is an impor-tant not-for-profit trade association dedicated to devel-oping and encouraging the adoption of open informa-tion standards in operations and maintenance (O&M):MIMOSA. The Common Conceptual Object Model(CCOM) provides a foundation for all MIMOSAstandards, while the Common Relational InformationSchema (CRIS) provides a mean to store enterpriseO&M information. MIMOSA also provides meta-data reference libraries and a series of informationexchange standards using XML and SQL. Our modelcan be considered a management reference model,i.e. describes the processes and the information flowsrequired to properly manage maintenance. Then, thisMMM is therefore linked with MIMOSA. In fact, allO&M information handled by the proposed model can(should) be structured according to MIMOSA stan-dards (for instance), although this subject is out of thescope of this paper.

4 MODELING A BUSINESS PROCESS

Business process modeling has been used in industrysince the 1990s to obtain a global vision of pro-cesses by means of support, control and monitoringactivities (Russel et al., 2006), to facilitate the com-prehension of the business key mechanisms, to be abase for the creation of appropriate information sys-tems, to improve the business structure and operation,to show the structure of changes made in business,to identify outsourcing opportunities, to facilitate thealignment of the information and communication tech-nologies with the business needs and strategies (Beck,et al., 2005), and for other activities like the automaticdocuments processing (Kalnins and Vitolins, 2006).

Nevertheless, during the last years, the research inthis field has increased enormously and with it andthe applications of the technology advances, businessprocess modeling has been used in fields as diverse

as: planning of managerial resources (ERP), integra-tion of managerial applications (EAI), management ofthe relations with the clients (CRM), management ofwork flows (WFM) and communication among usersto facilitate the management requirements (Russel,et al. 2006) (Ramzan and Ikram, 2007).

Some benefits reported from the adoption of busi-ness process modeling are: improvement of the accom-plishment speed of business processes, increase of theclients’ satisfaction, optimization and elimination ofunnecessary tasks and incorporation of clients andpartners in the business processes. (Pérez, 2007).

Software process and Business process present cer-tain similarities, being the most common of them thefact that both try to capture the principal characteristicsof a group of partially tidy activities that are carried outto achieve a specific goal. Now then, whereas the aimof a process software is to obtain a software product(Acuña and Ferré, 2001), the aim of a business processis to obtain beneficial results (generally a product orservice) for clients or others affected by the process(Sharp and McDermott, 2000).

In fact, the origins of the different business processmodeling languages are inspired in the software mod-eling languages; as well a computer approach definesmodeling as the “designing of software applicationsbefore coding” (OMG), this approach has allowed thedevelopment of several languages and applications forcode generation and processes automation, which havebeen notoriously increased in quantity and diversityspecially during the last two decades.

There are a large number of business processmod-eling languages. In a general classification a modelinglanguage can be graphical or textual (Xiao He, 2007).

Considering that the objective of this research is tomodel a new business process and that it is desiredto work with a graphical representation, an analysisof the different options reveal that the better choice isusing UML language; which is a standard maintainedby the OMG (Object Management Group).

UML was created in 1997 by the called “threefriends”: Grady Booch, James Rumbaugh and IvarJacobson, who put it to consideration of the OMG,being accepted as a standard since the same year.

UML is formed by nine kinds of diagrams thatshow a specific static or dynamic aspect of a system(Aguilar-Savén, 2004).

For this research the software chosen to model thesystem is Enterprise Architect 7.1, an UML analy-sis, design, documentation and project managementCASE tool, including basic UML models plus testing,metrics, change management, defect tracking and userinterface design extensions; developed by Sparx Sys-tems. Enterprise Architect 7.1 was chosen because itsfeatures and its availability to support this research.

Using Enterprise Architect 7.1, the general stepsto model the proposed MMM and that are shown inthis article are: (i) definition of the business archi-tecture, (ii) modeling of goals tree, (iii) identificationof top value chain process, (iv) modeling of involvedprocesses and activities, (v) tracing required UML

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diagrams to represent specific features of the system(i.e. state diagrams).

5 BUSINESS ARCHITECTUREAND STRATEGY

Figure 2 shows a diagram generated using the Enter-prise Architect 7.1 software and that represent thegeneral business architecture of the proposed MMM.This diagram contains the three principal categoriesdefining the architecture: the Business Context (mod-els of all involved stakeholders, mission and visionstatements, business goals and physical structure ofthe business “as-is”), the Business Objects (a domainmodel of all objects of interest and their respectivedata), and the Business Workflows (business pro-cess drawing on stakeholders, structures and objects

Figure 2. General business architecture for the proposedMMM.

defined in the Context and Objects packages show-ing how these work together to provide fundamentalbusiness activities).

Generally the business architecture is organizedhierarchically in order executives can observe howspecific processes are aligned to support the organiza-tion’s strategic aims (Harmon, 2007).

Due there is not a standard to name the processlevels, the proposed MMM has its own nomenclatureto refer to its hierarchical levels.

Once defined the type of architecture to be used itis necessary to model the system goals as a part of thestrategy.

In Fig. 3 is represented the goals tree designed forthe proposed MMM using a specific type of UMLdiagram: an object diagram. In these diagrams a goalis described as class object with the stereotype «goal».Due it is the design of a new system all the goals areof qualitative type.

For this MMM it is considered the main goal as “toimprove continuously the maintenance system” andthat it depends on the fulfilment of other three goals(identified by a dependency line): to decrease the totalmaintenance cost, to increase the assets availabilityand to attend property the non confor mances detectedin the maintenance management system.

It is necessary to notice that the first two aims (todecrease the total maintenance cost and to increasethe assets availability) are contradictory goals and areidentified using an association line between them.

Also the fulfilment of each one of the alreadymentioned goals depends on another series of hier-archical goals (or sub-goals), which have to be totallyor partially achieved, a tag indicates this condition.

The macro-processes, processes and activitiesdescribed in the model are focused to the satisfactionof the objectives drafted in the goals tree diagram.

6 MODELING THE PROPOSEDMAINTENANCE MANAGEMENT SYSTEM

The top value chain process of the proposed MMM(or Level 0 process) is conformed by the alreadymentioned four macro-processes: Planning, Support,Maintenance Execution and Control & Improvement.Subsequently each macro-process is conformed byprocesses (Level 1 processes) and each process is sub-divided in sub-process (Level 2 processes), finallyeach process is subdivided in activities (Level 3processes).

As an example of modeling, in Fig. 4 appears anUML diagram in which the Control & Improvementmacro-process (Level 1) is modeled.

Every macro-process and process modeled hassome invariable related elements: one or several goalsassociated using a dependence relation with the stereo-type «achieve» (these goals are derived from the goalstree); input resources, output resources, both linkedusing dependence relations, supply resources with a

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Figure 3. Goals tree diagram for the proposed MMM.

dependence relation and the stereotype «supply» andcontrol resources having the stereotype «control».

The mentioned elements are visible in the diagramof Fig. 4.

Inside the macro-process of Control & Improve-ment there are some other processes (Level 2) andactivities (Level 3). To represent them it could be usedalso an UML diagram or a more specific tool like aBPMN diagram, a simple flow diagram. That decisiondepends on the project specifications.

Finally Fig. 5 represents an UML State Diagramdetailing the transitions or changes of state that anobject (in this case a Maintenance Work Order) can gothrough in the system. This kind of diagrams showshow an object moves from one state to another and therules that govern that change.

State charts typically have a start and end condition(Milestone Consulting, 2001–2007).

7 CONCLUSIONS

The maintenance model expressed in this work departsfrom an analysis done to a set of representativeprevious models, in order to have a new model con-stituted by the best characteristics observed. Themodeling work has involved a research about somebasic concepts (business process, modeling, model-ing language, business architecture, etc.) to selectthe most suitable language and software tool for theparticular case.

In this paper is presented only a significant part ofthe modeling process made about the proposed model.

The MMM modeled is strongly inspired by the ISO9001:2008 standard. A future challenge in this areacould be the addition of elements derived of the PAS55 as well as technical tools recommended to the oper-ation of the maintenance function. Increasing the depth

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Figure 4. UML Diagram of the macro-process of control & improvement.

Figure 5. State diagram of a maintenance work order.

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of a particular process of the model and doing it morespecific could add also its value. Code generation(with everything it implies) would be a subsequentobjective for this maintenance model proposal and agood opportunity of applying it in a practical case.

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