The work shows a methodology for the design of a general indicator for the evaluation of the Maintenance Management Level in a company, for which, first, a ranking of the key indicators for this purpose is developed according to their influence on decision-making. using group work (experts) and using the Saaty AHP method.
All this with a proactive vision of the maintenance management control activity, contributing to the achievement of greater efficiency and effectiveness of this process and to the continuous improvement of the organization's actions.
1. Introduction
Maintenance is an integrative discipline that guarantees the availability, functionality and conservation of the equipment, provided it is applied correctly, at a competitive cost. Today, maintenance is destined to be one of the fundamental pillars of any company that respects itself and considers itself competitive. Among the various ways of conceptualizing maintenance, the one that seems to be the most current, and at the same time more comprehensive, is the one that defines it as “the set of activities aimed at guaranteeing, at the lowest possible cost, the maximum availability of the equipment for production; seen this through the prevention of the occurrence of failures and the identification and signaling of the causes of the equipment's deficient operation ”.
At the beginning of any Improvement process, whether at a personal or organizational level, it is required, as a first stage, to become aware of reality and, subsequently, to define the objectives to be achieved. Meanwhile, once the process has started, it is necessary to monitor the progress achieved, through observations and comparisons over time, of parameters that clearly define the degree of quality of said performance, verifying, without subjectivism, whether it has been improved with with respect to the beginning of the period.
Why evaluate and control maintenance management in companies? Simply because it is necessary to know how efficient is the application of the maintenance policy that has been planned for the productive environment of the company.
This information allows us to act quickly and accurately on weak factors in our maintenance. A good policy to control and evaluate maintenance management in the company results from the implementation, study and analysis of a package of indicators.
A relatively large number of indices have been suggested to monitor its performance, with results not always consistent. In reality, the amount of indicators disclosed by the specialized bibliography for this purpose becomes a bit confusing, especially if there is no culture regarding their use in the company.
It is evident that when selecting those “few” indices that most effectively describe maintenance performance, it is essential to take into account the modern conception of the maintenance activity, essentially linked to its objectives, that is, what is related to it. expected.
Currently, decision-making regarding the performance of maintenance systems is indisputably a first-order aspect to be resolved, since by guaranteeing the same, not only the adequate evaluation and control of maintenance management with a view to to achieve its continuous improvement, but also the achievement of a greater availability of the productive capacities installed in the entity under study; since in practice the decision-making process in this area is made difficult by the fact that a wide range of indicators proposed in this regard are available without a clear definition of the degree of importance of each one of them when assessing the influence of the maintenance activity on the organization's goal.
The general objective pursued in this article consists of defining the key indicators for evaluating the performance of the maintenance activity, as well as their ranking according to their level of influence in the decision-making process.
2. The maintenance indicators
At the beginning of any improvement process, whether at the level of individuals or organizations, it requires, as a first stage, that awareness of reality be acquired and later, that the objectives to be achieved and the means to do so are defined.
Meanwhile, once the process has started, it is necessary to monitor the progress achieved, through observations and comparisons, over time, of parameters that clearly define the level of quality of organizational performance, verifying, without subjectivism, if it has improved or not compared to the initial situation.
As regards maintenance activity in an industrial company, the need for such a procedure is much more recognized. A relatively large variety of indicators have been suggested to monitor their performance, with results not always consistent.
It would be difficult to understand the study carried out in this section without first pausing in the analysis of the following definition:
Indicator or Index: It is a numerical parameter that provides information on a critical factor identified in the organization, in the processes or in people with respect to the expectations or perception of customers in terms of cost-quality and deadlines.
Indicators have traditionally been viewed reactively, that is, using them to look back with a view to planning for the future, however, a change has been provoked in this sense aimed at using indicators with a proactive vision, that is, to make decisions into the future, managing them.
The fundamental characteristics that the maintenance indicators must meet, always with an eye on what it is desired to achieve with industrial maintenance, are the following:
- Few, but enough to analyze the management. Clear to understand and calculate. Useful to quickly know how things are going and why.
That is why the indexes must: Identify the key factors of maintenance and their impact on production. Provide the necessary elements that allow a thorough evaluation of the activity in question. Establish a data record that allows its periodic calculation. Establish plan or consignment values that determine the objectives to be achieved. Check the proposed objectives by comparing the actual values with the planned or target values. Facilitate decision-making and timely actions in the face of deviations that arise.
As a suggestion for the analysis of the indices, it can be pointed out:
1. The analysis should not present speculative conclusions. The variations to improve or to worsen should be taken as symptoms that were discussed jointly between the control and execution departments and may indicate needs to change working methods.
2. Before issuing comments on the results of the index analysis, the supervisory body must be sure that the data that originated them are reliable.
3. The analysis must have negative observations that must be accompanied by suggestions for alternatives to improve that must be discussed with the supervisors of the maintenance execution area before recording in the analysis report.
4. The placement of comparative values is valid, between different periods or average values obtained in the previous year, for examination with respect to the results of managerial provisions, taken based on previous analyzes.
5. Establish goals for the improvement of the indexes, together with the performing area.
It is important, for working with the indicators, to bear in mind the most common errors or defects that have been incurred in the places where work has been done in this regard, they are the following:
- Inadequate selection of the indices, excessive in number and not ranked. Insufficient and confusing definition that causes different interpretations and / or calculations. Little or no identification of the relationship between the index and the critical factors. Inadequate data collection systems for the calculation of the indices, erroneous calculations and / or obtained with delay, with which the aptitude and speed of action is lost. Lack of establishment of objective values and difficulties in obtaining adequate information. Lack of systematic controls. Delay in making decisions.
The control indices in maintenance management must be differentiated in terms of volume and characteristics, this differentiation being subject to the management levels of the entity. The effectiveness of the maintenance function is difficult to measure in an isolated way, since its actions cannot be considered independent, but rather framed in work teams and related to other departments.
Within the application, execution, and control of a maintenance system there are different stages, which can be measured through the citation of different indices (Intervention, defects, work forces) that in their determination will allow to analyze the development of the applied system. Relying on the information provided by these indices as a means of control, the quality of the maintenance carried out can be determined and thus the deficiencies in the system can be corrected.
There are a large number of authors who have been interested in trying to solve the problems of maintenance control given the important role that maintenance plays in different companies. One of the main documents on the subject is the one carried out by Tavares, where he raises a series of indicators which are divided into four fundamental groups
Other authors in addition to coincidences with Tavares also propose other indices such as Operational Reliability, Utilization, Maintainability, Average Life Time, a series of primary elements with which an important group of indicators can be calculated for better control of maintenance, among others.
3. Determination of the Maintenance Management Level in the company
Starting from the hypothesis that there is a set of indicators by which it is possible to carry out an evaluation of the maintenance status and that the improvement of these indices raises the level of excellence in maintenance management and that in turn said improvement has a positive impact on the economic results of the company, is that all the necessary steps to define and determine the Maintenance Management Level (NGM) are developed in this section.
3.1 Determination of a Maintenance Management Pattern and its desired state
To develop this section, two stages are used:
1. Select from a large set of indices, the main ones to measure the performance of maintenance management.
2. Characterization of indexes (factors) that measure the level of maintenance management.
3.1.1 Establishment of the set of indicators to measure the level of maintenance management
Based on previous studies, consulting experience and an adequate bibliographic review, more than 110 indicators or variables are obtained that measure the operation of maintenance (technical, organizational, economic-financial and social).
After consulting experts and taking into account only the fundamental variables generally measured by leading companies, a decantation iteration was carried out, leaving a reduced list of 28 indicators (variables), which are stratified by determining the eight factors in charge. to evaluate maintenance management, which are detailed below:
1. Information level.
2. Total Effective Productivity of Equipment (PTEE)
3. Level of incidence of the maintenance function in the costs of the company.
4. Existence of a formal system of measures to determine the effectiveness of maintenance.
5. Ability of maintenance workers to successfully cope with the problems corresponding to this function.
6. Existence of a formal system for planning and scheduling maintenance work.
7. Level of adoption of computerized maintenance systems.
8. Safety of personnel and the environment.
3.1.2 Characterization of the measurement factors of the Maintenance Management Level
In this section, the characterization of each of the factors identified in the previous section is carried out.
Information level
The objective of this factor is to evaluate the availability, in the entity, of the information necessary for making decisions regarding maintenance management.
In this way, the aim is to verify the availability of all the technical information, the operating characteristics, the location, the priority of the equipment, the current status, the maintenance plans, the work orders executed and to be executed, the costs of labor of work, materials and spare parts in different periods, the personnel who have intervened the equipment, components and spare parts associated with it, the relevant notes on the equipment, the location within the system (hierarchy), the downtimes, the failure modes and its causes, operating times, alarm signals, purchase value, supplier, date of acquisition of the good and in general all the information required to manage its maintenance, as well as for use in other areas: warehouse, operation, commercial, assemblies, among others.
Total Effective Equipment Productivity (PTEE)
The PTEE is a measure of the actual productivity of the teams. This measure is obtained according to equation 1.
PTEE = AE X OEE (1)
This is a measure that indicates the amount of calendar time used by teams.
This measurement is sensitive to the time that the equipment could have operated, the AE can be interpreted as a percentage of the calendar time that a equipment has used to produce.
To calculate the AE, the steps detailed below can be applied.
1. Set the calculation base time or calendar time (TC).
2. Get the total unscheduled time
3. Get the planned stoppage time
4. Calculate the operating time (TF, See equation 2)
TF = Calendar time - (Total unscheduled time + Planned downtime) (2)
Resulting in the calculation of the use of the equipment as shown in equation 3.
AE = (TF / TC) X 100 (3)
Y represents the percentage of calendar time that is actually used to produce.
OEE- Overall Equipment Effectiveness
This metric assesses the performance of the computer while it is running. The OEE is strongly related to the state of conservation and productivity of the equipment while it is operating.
It should be noted that this indicator is managed on a daily basis and is composed of the following three factors:
- Availability: Measures the loss of equipment availability due to unscheduled shutdowns.
Where:
Net time available = Overtime + Total time programmed + Stop time allowed (5)
Operating time = Net time available - Line stop time (6)
- Efficiency: Measures performance losses caused by equipment malfunction, not operating at the original speed and performance determined by the equipment manufacturer or design.
Where:
(8)
- First Time Quality (FTT): These quality losses represent the time taken to produce products that are defective or have quality problems. This time is wasted, as the product must be destroyed or re-processed.
Where:
Total defective parts = defective parts + rework or recoveries (10)
The calculation of the OEE is obtained by multiplying the previous three terms expressed as a percentage.
OEE = Availability X Efficiency X FTT (11)
The OEE is used to build comparative indices between plants (benchmarking) for similar or different equipment. For complex production lines, OEE must be calculated for component equipment.
This information will be useful to define the type of equipment in which it is necessary to affect with greater priority with maintenance actions.
Impact level of the maintenance function on the company's costs
The efficiency of all activity within the company with a view to achieving reasonable costs of the system as a whole is an issue that is closely monitored by every manager in today's organizations.
Studies carried out regarding the costs associated with the maintenance of the production plants showed that they can represent between 10 and 25% of the total manufacturing cost of the product that is produced.
In the maintenance area, it is advisable to control a series of indices related to the costs associated with it; Within them, the following should be considered:
- Relative cost with own personnel Component of maintenance cost Relative cost with material External labor cost Maintenance cost in relation to production Training cost Fixed in spare parts Maintenance cost per sales value Global cost
Existence of a formal system of measures to determine the effectiveness of maintenance
At present, every company manager knows the importance of measuring the performance of the maintenance activity, simply because it is necessary to know how efficient is the application of the maintenance policy that has been planned for the productive environment of the company.
This information allows to act quickly and accurately on weak factors in maintenance management. On the other hand, the challenge is what to measure and how to do it in the best way.
One of the tools that allows and constitutes one of the basic elements of efficient maintenance management is maintaining a correct measurement system.
Said system should not only allow the efficiency and progress of repairs to be measured, but it should also allow one of the main activities of any management, decision-making. Determining if the measurement and control system allows an adequate development of maintenance operations is one of the most difficult, essential and determining tasks that an executive can face.
It should be made clear that it is not necessary to have many indicators under continuous control, but only the most important, the key ones. Metrics that easily encompass total business performance should be given top priority. The package of indicators can be higher or lower, depending on the type of business and its specific needs.
Ability of maintenance workers to successfully deal with problems corresponding to this role
The personnel who work in an organization, whatever the sector of the economy or type of industry, building, etc., must have certain skills that are basic to them and that have to do with their predisposition to perform technical tasks.
Based on the daily performance of the staff, it must be evaluated to what extent they are able to carry out the necessary tasks in the maintenance area in order to meet business goals.
All labor control mechanisms must be oriented in the sense of obtaining greater use of the available human resources as a whole, as well as providing the personnel with greater security and satisfaction in the performance of their duties.
In this factor, it is proposed to consider the following indicators:
- Work on scheduled maintenance Work on corrective maintenance Other activities of maintenance personnel Training of maintenance personnel School level of maintenance workers Uncalculated hours of maintenance personnel Accident frequency and severity rate Fluctuation level of maintenance labor
Existence of a formal process for planning and scheduling maintenance work
In this factor, it must be specified to what extent there is a formal system for planning maintenance activities in the entity analyzed. The key elements that any system of this type must have for the maintenance function are specified below.
1. Planning. It implies the reasoned and coherent definition of:
- Policies: Clear approaches that define the field of action, the principles that will frame maintenance performance. Objectives: Congruent and realistic expression of the result that is expected to be achieved within a specified period. Plans: Put in writing the result of the planning work for its subsequent monitoring, evaluation and feedback. Programs: Projection of activities with criteria of opportunity and chronological sequence, which incorporates desired products and those responsible for their achievement. Methods: It is about selecting, within a range of possibilities and adjusting to the available resources, the optimal way to carry out the programmed activities (Outsourcing is considered).Procedures: To achieve uniformity and consistency in the level of execution of maintenance work, it is necessary to detail the steps to follow and generate a standard. Budgets: It involves a structured detail of the forecast of resources necessary to achieve the proposed objectives.
2. Organization: Requires specific knowledge and, at the same time, a global vision of the maintenance unit to integrate:
- Positions: Entities that group consistent objectives, functions and responsibilities. Functions: Tasks to be carried out that are related to the profile of the position. Authority: Property to make decisions and generate orders that allow the fulfillment of the objectives of the position. Responsibility: It is the obligation that is contracted before the higher authorities for the achievement of the proposed objectives based on the resources assigned. Resources: It is the distribution of human resources, equipment, machinery, tools and other materials necessary for maintenance work.
3. Execution: Its effectiveness is determined by the anticipation of needs, systematization, support actions and facilities for the:
- Communication: It is necessary to define the needs and based on this, the internal and external communication system to the maintenance unit.
Level of adoption of computerized maintenance management systems
Automated maintenance management systems are very useful as they provide updated, timely and corporate-use information on the assets registered in it.
The computerization of a Comprehensive Maintenance Management System must include:
- Computerization of technical maintenance information. lnformatization of the Corrective Maintenance System. lnformatization of the Preventive / Predictive Maintenance System. Computerization of the programmed shutdown system. lnformatization of the Maintenance Management Monitoring and Control System.
1. Systematic monitoring and control (Monthly)
2. Monitoring and controls on request
- Interfaces with other computer applications.
Naturally, prior to this automation, an adequate study of the information that will be collected in these documents and the establishment of standards, procedures and operating circuits of the Executive Maintenance Line is necessary.
Safety of personnel and the environment
This element has grown in recent years at the business level and especially in the maintenance area given the importance of guaranteeing adequate working conditions for the operators (their safety) and the protection of the environment.
Regarding the safety of personnel, the level of incidence of failures or failure modes on it in the workplace must be assessed (if someone can be injured or killed, either as a direct result of the failure mode itself, either as a result of other damages that could be caused by the failure).
In addition, it is important to determine to what extent maintenance management takes into account the requirements of environmental regulations.
3.2 Determination of the weight according to the degree of importance of the factors that evaluate the Maintenance Management Level (NGM)
The determination of the weight of each factor will be carried out using well-founded mathematical methods. First, through the use of a group of experts and the application of the AHP method (Analytic Hierarchy Process) or Thomas Saaty's Hierarchical Analytic method, comparisons of criteria taken in pairs by each of the experts must be carried out.
Selection of the priority matrix
Assuming that n criteria are considered in a given hierarchy, the procedure established by Saaty for determining the weights establishes a square matrix (A) that reflects the judgment of a certain expert on the relative importance of the different criteria. The comparison is made in pairs, so that the criterion of row i (i = 1, 2,…, n) is classified in relation to each of the criteria represented by the n columns. Let aij be the element (i, j) of “A”, the AHP proposes the use of a direct scale from 1 to 9 in which aij = 1 means that criteria i and j have the same importance, aij = 3 implies that i is slightly more important than j, if the element is 5 the importance of i with respect to j is slightly greater,a 7 indicates a demonstrated importance and a 9 would imply that the importance of i is extreme with respect to j. For consistency, if aij = k, aji = 1 / k. Also all elements aii must be equal to 1.
By applying this action by the experts selected to evaluate the eight decided factors, the priority matrix (Matrix A) shown below is obtained.
Matrix A
Normalization of matrix A and calculation of the weights of each attribute
After evaluating the criteria in matrix “A”, using the previous scale, the matrix is normalized. Then the weights will be obtained as the average of the row of the resulting normalized matrix (N).
Matrix N
Determination of the level or reason of inconsistency (CR) in the judgment issued by each expert
When the columns of the matrix “N” are identical, it can be said that the original matrix of pairwise comparisons (A) is perfectly consistent. Consistency means that the decision shows consistent judgment when specifying the attribute pair comparison. Mathematically it is expressed as follows: aik = aij * ajk, for all i, j, k.
Because these matrices of comparisons between attributes are made according to human judgment, some degree of inconsistency is expected that must be tolerated provided it is not irrational. To determine whether or not a level of inconsistency is reasonable, a quantifiable measure needs to be developed for the comparison matrix "A", for which the mean of the elements of each row of the normalized matrix (N) is calculated, constituting this the priority vector (V) (weights of the alternatives).
Matrix V
Once the priority matrix is available, we proceed to calculate the vector of the weighted sums (K), which is obtained as a result of the sum of the multiplications of each priority with a column of matrix A, which it will always be carried out between a column of said matrix and the element that is in the row that is numbered with the value to which said column belongs.
Vector K
If the elements of the vector of weighted sums (K) and the corresponding priority value are now divided, the values of are obtained and then the mean of these values will be called max., With which the Consistency Index can be calculated:
max = 8, 215542
(13)
Now the degree of consistency is calculated, which must be at 0.10 for the experts' judgment to be considered consistent, otherwise the determination they make on the weight of the factors will not be valid.
(14)
Where:
Expert judgment is consistent.
3.3 Defining the intervals for the NGM measuring factors
To establish the levels of behavior of the indicators, a work was carried out with the experts, obtaining a scale of five divisions:
- Very good Good Fair Bad Very bad
A score of 10 was assigned; 8; 6; two; 1, respectively, figures that will later be used to calculate the final indicator (Maintenance Management Level).
In order to establish itself in the first levels, the company must present full compliance with the parameters that govern the factor in question, obtaining a rating of Very good only when this is fully achieved; The Regular category will be applied to factors that present some type of difficulty, while Bad and Very bad, to those that do not meet the factor requirements compared to leading companies, or with respect to meters or indices. that define it.
3.4 Determination of the Maintenance Management Level
To achieve a final evaluation of the situation of the company, an indicator is needed that relates the eight factors that have been used so far, for this it is proposed to calculate the Maintenance Management Level, where the score given by the experts is related from the company to each of the meters (according to the real behavior of the entity studied)
with the weights obtained previously (matrix V) and the maximum value of the measuring variables (10 points) with the respective weights according to the degree of importance; which responds to the following mathematical expression:
Where:
NGM: Maintenance Management Level (in%)
Pi: Relative weight of the characteristics of the pattern of excellence
Zi: Qualification given to the variable or characteristic i of the pattern of excellence.
n: Number of variables (in this case eight factors)
Conclusions
1. The maintenance control activity in the company requires scientific-technical rigor, otherwise it remains a good intention that may discredit it and cause problems in the subsequent development of its productive activity.
2. The existence of a wide range of indicators for evaluating maintenance activity makes the decision-making process somewhat difficult as the indices considered key to said function are not defined.
3. The proposed indicator constitutes an adequate tool for improving the maintenance function in the company, so it is recommended to analyze the behavior of each factor evaluated in the NGM in order to identify the causes that cause its poor performance and work for overcoming them.
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