History Of Reliability And Maintainability Management

Published Date: 02 Nov 2017

The exceedingly beneficial results of reliability and maintainability have increased the usage of its models and theories in almost all the aspects of life. In the past couple of decades, there was enormous growth in reliability and maintainability literature publication and implementations in the engineering as well as other fields. The essence of this theme is to achieve the most reliable systems at the minimal initial cost and also to optimize the functioning expenses. This leads to the field of reliability and maintainability management and its performance in engineering companies, plant, civil construction and other fields of technologies. Reliability and maintainability specialists take into account various management aspects, such as contracts, economics, value analysis, quality control, optimizing equipment repair facilities and many others, in order to produce more reliable and maintainable products at minimal cost.

The main theme of this report is to provide sufficient knowledge in light of the importance of management, in the area of reliability and maintainability. The increase involvement of management is essential to improve the system readiness and reliability as well as to lessen acquisition and operational costs. The best efforts are put together in order to provide the readers concise knowledge about the topic leading to the references for detail study and further research.

Chapter 2 – Literature Review

Section 1- Understanding Reliability and Maintainability Management

Reliability Management

Management is an integrated process by which persons with authority create, operate and maintain an organization in the selection and completion of the objectives. Various factors are taken into consideration for managing reliability functions known as reliability management, are described in detail.

Corporate Policy for Reliability

It is important requirement for the existence of reliability function in an organization where the achievement of high reliability is recognized as part of the corporate strategy and top management always pays attention to it. If management does not have appropriate awareness then the reliability functions and efforts are always put at the back whenever cost control and time lines pressures exist. There will be low morale in the reliability members and they will be considered separate from the project team as well. Therefore, quality and reliability awareness and direction must start at the top and must permeate all functions and levels where reliability can be affected.

Integrated Reliability Programs

It is essential that reliability functions and programs are always considered as an integral part of the product development and not as a parallel entity. The top management is considered responsible to ensure reliability functions are properly taken into consideration as per the requirement of the project. Therefore, the major responsibility lies to the project manager. Normally, specialist reliability services and support is provided from a central department in a matrix management structure, at the same time the responsibility for reliability achievement must always be the responsibility of the project manager, who is the only person who ensures that the right balance exists in allocating resources and time between different areas of the project or product development life cycle.

One of the important aspects of quality control effort is that it must be responsive to the reliability requirements and not be directed only at costs reduction or as an inspection tool only, at the final stage of the product development. Quality control can contribute effectively to the reliability functions if:

Quality procedures, such as test and inspection criteria, are related to factors which can affect reliability, and not only to form and function.

Quality control test and inspection data are integrated with the other reliability data.

Quality control personnel are trained to recognize the relevance of their work to reliability, and trained and motivated to contribute.

It is also essential that disciplined to be there in an integrated reliability programme. Also in project or a product life cycle reliability efforts and functions implementation should be ensured through proper guidelines and rules. The disciplines of design analysis, test, reporting, failure analysis and corrective action must be strictly imposed, as any relaxation can result in a reduction of reliability.

The useful guidelines for developing reliability programs are illustrated in the diagram.

Figure: Useful guidelines for developing reliability programs

Reliability and Costs

Achieving high reliability involves efforts from experienced personnel and a lot of research analysis which is expensive, especially when the product is complex or involves new technology. The reliability management requires the resources like trained engineers, management time, test equipment and products for testing. Sometimes, it appears difficult to justify the necessary expenditure in the quest for a vague quantity such as reliability. On the other hand, it is obvious and a true fact that efforts put together for the reliability management functions always pay off.

Specifying Reliability

The important measures are to ensure the fact that during design, development and manufacturing stages of the product life cycle reliability is given appropriate attention and resources to implement the functions at every stage as per the requirement.

It is important factor to avoid writing vague requirement, such as "as reliable as possible", "high reliability is to be a feature of the design". This type of statement did not provide assurance against reliability aspects and efforts which are compromised.

The reliability specification must include following:

A definition of failure related to the product’s function. The definition should cover all failure modes relevant to the function.

A full description of the environments in which the product will be stored, transported, operated and maintained.

A statement of the reliability requirement and a statement of failure modes and effects which are particularly critical and which must therefore have a very low probability of occurrence.

Project Reliability Plan

The success of the project depends upon reliability plan and its appropriate implementation. All the projects should have reliability plan according to the requirements and to be utilized as necessary. The requirements and procedures are incorporated in the reliability plan after collecting data from the concerned parties and is a part of the reliability plan produced.

The reliability plan normally comprise of:

A brief statement of the reliability requirement.

The organization for reliability.

The reliability activities that will be performed (such as: design analysis, test, reports. etc).

The timing of all major activities, in relation to the project development milestones.

Reliability management of suppliers.

The standards, specifications and internal procedures (e.g. the reliability manual).

Cost effective approach to Reliability and Maintainability

Life cycle costs are associated with acquiring, operating and maintaining equipment or an item. This is also referred to as total costs incurred over the period of ownership of an item.

Life cycle costing mainly consists of following costs:

Acquisition cost (AQ): capital cost plus cost of installation transport, etc.

Ownership cost (OC): cost of preventive and corrective maintenance and of modifications.

Operating cost: cost of materials and energy.

Administration cost: cost of data acquisition and analysis.

Reliability functions and maintainability and safety parameter influences the total cost or life cycle costs as described:

Reliability determines spares requirements and determines loss of revenue. Moreover, maintainability affects training, test equipment, down time and manpower. In addition to that safety factors involve operating efficiency, maintainability and liability costs.

Life-cycle cost is reduced by improving reliability, maintainability and safety but at the same time the activities needed to achieve them are increased. Because of this fact always an optimum solution is designed to achieve best results within the cost limitations.

Figure: Availability and Cost-manufacturer Figure: Availability and Cost-user

In the above diagrams the comparison is illustrated between the availability and cost parameters. The pre-delivery costs of manufacturer that consists of design cost, procurement and manufacturing of the products increases with availability. On the other side after delivery costs of manufacturer which comprise of warranty, redesign and loss of reputation, decrease as availability improves. The total cost is drawn by a curve indicating value of availability at which minimum cost is incurred.

On the other hand, user cost involves addition of losses and expenses which is represented by a curve in the above figure. The result is a curve which depicts solution of an optimum availability that incurs minimum cost. It is clear from the above mentioned analysis and figures that cost is minimized by finding reliability and maintainability enhancement which ultimately results in saving over the life of the item.

Maintainability Management

A systematic management approach is essential for the effective implementation and utilization of maintainability functions in design and engineering phases of product or an item. Maintainability management is a complete discipline which involves the principles and set of rules to manage maintainability function within an organization's structure, and the role of maintainability during all the stages in the life cycle of the product.

Effective maintainability management is the sole priority for the success and mainly depends upon following factors:

An acceptance is required from the top management admitting that maintainability is an essential characteristic of equipment design

Establishment of a maintainability engineering discipline at a level within the organization that facilitates efficient relationships building with respect to other organization entities

Acceptance throughout the organization of maintainability as a technical discipline on a equivalence with design, maintenance, human factors, reliability, testing and evaluation, integrated logistic support and safety engineering. These are the disciplines which have strong interrelation with maintainability.

Planning, organizing, directing, controlling, budgeting, and monitoring of the maintainability function is also an important and essential part of the maintainability management function.

Maintainability Management Functions in Product Life Cycle

In order to attain an efficient design it is essential to consider maintainability factors and concerns that may arise in the product life cycle. This type of program mainly incorporates exchange of information and specifications between the user and manufacturer during the life cycle of the product. This document comprise of maintenance as well as other related requirements of the product and the manufacturer’s response to these requirements.

The product life cycle is primarily composed of the four phases as described in the figure. These phases are the concept development phase, validation phase, production phase, and the operation phase. Each phase has maintainability functions specifically associated to them as per the necessary requirements.

Figure: Product Life Cycle Phase (PLC)

Maintainability Management Organization Functions

There are several functions and jobs performed by maintainability staff in an organization culture. These major functions are mainly grouped into categorizes as described:

Analysis

Design

Administration

Coordination and Documentation

Analysis

The main efforts are put together by a maintainability organization on the allocation of maintainability, maintainability prediction and field data evaluation for the projects in question. The major functions related to this specific analysis includes examining the product specification documents with respect to maintainability requirements; performing maintainability allocation and prediction studies; analyzing maintainability feedback data obtained from the field and other available sources; taking considerable part in product engineering analysis for the sake of maintainability perspective; gathering and sequencing maintainability demonstration documents; analyzing and performing required maintenance analysis; and participating in meetings and conferences regarding maintainability analysis. These are the main analytical points which are taken into consideration by the maintainability department.

Design

The main focus of maintainability design is on those features and characteristics that relate with the ease of maintenance, make maintenance more cost-effective, and as a result reduce logistic support needs.

The main features which are part of this section involve:

Preparation of the design reports

Effective participation of the maintainability team in design reviews

Monitoring designs at different stages

Approval of design drawings from maintainability point of view

Consultation of services

Taking part in preparation of maintainability documents

Administration

The administrative function comprise of the tasks related with the cost, timeline and performance parameters. It also provides guidelines for managing and control of maintainability management.

The main points of maintainability administration are as follows:

Organizing and Staffing

Preparation of maintainability program plan

Budgeting and scheduling preparation

Assigning responsibilities to the staff

Developing procedures and policies and their effective execution

Coordination and Documentation

Coordination and documentation regarding maintainability perspective are the most important functions of the management staff. The documentation involves gathering of information regarding maintainability management, design review results and data of the product in question. The function of coordination is mainly concerned with the interfaces with various parties involved which are subcontractors, customers and system engineering.

Centralized organization

The role of a maintainability department in an organization is as a distinct line department where the complete authority lies with a single manager, the operating system of this type of organization is called centralized system.

This sort of arrangement gives emphasis to maintainability as a design discipline and is most effective and efficient when both the parties recognize maintainability as a necessary portion of an engineering design. This sort of organization culture is best suitable in scenarios when either there is a single big project or multiple small projects having similar output/products and customers. The organization chart of a centralized organization exhibiting the role of maintainability department/personnel is shown in the figure.

Figure: Maintainability as line organization with the overall engineering department

In addition to maintainability engineers, there are other engineering professionals of different skills and aptitude, who indirectly contribute to product maintainability and are part of maintainability organization. The key personnel are the reliability engineers, quality control engineers, human factors engineers, and safety engineers.

Section 2- Reliability and Maintainability Mathematics

Reliability and Maintainability Mathematics

In order to do various analysis regarding systems reliability and maintainability, mathematical terminologies understanding is essential. In this section efforts are put together to briefly describe these terminologies along with their necessary requirements.

Laplace Transforms

The Laplace transform, F(s) of a function f(t) is given by:

Binomial Theorem

For positive "k" the binomial theorem will be:

Maxima and Minima

Whenever there is a requirement to make decisions regarding reliability perspective and maintainability functions of an item in question, it is preferable to find the maxima and minima of that function. The process to find the maxima and minima of a single variable function is described as follows:

At time, t=t1 , the function f(t), will either be at a maximum or a minimum if the following conditions are fulfilled:

Maximum- if f’(t1) = 0 and f"(t1) < 0. The single prime denotes differentiation with respect to variable "t" and the double prime denotes the second derivate with respect to "t".

Minimum- if f’(t1) = 0 and f"(t1) > 0.

Mean Value Theorem for Integrals

If we have a continuous function f(t), under consideration, then the mean value of this function is described as:

Basic Probability

The concept of probability is defined by making assumption that,"an event can occur in "m" ways and in "n" ways it fails to occur." The total numbers of ways, which are (m+n) are always considered as equally likely. In this case the probability of this event occurrence is:

The probability of the event’s occurrence plus the probability of its non-occurrence is always equal to "1", as shown:

Mutually Exclusive Units

The mutually exclusive behaviour of two or more events means that the occurrence of any one of the events does not include the occurrence of the remaining events; in this case the events are mutually exclusive.

Where "P" is the probability.

Independent Event

When the occurrence or non-occurrence of any one of the n events did not affect the occurrence probabilities of any of the other (n-1) events, in this case all of the "n" events are known as independent events.

Dependent Events

If the occurrence or non-occurrence of any one of the n events affects the occurrence probabilities of any of the other (n-1) events, in this case all of the "n" events are known as dependent events.

The conditional probability is described as:

Probability Distribution

The total area under the continuous probability density function is

Figure: Cummulative distribution function

Exponential Distribution

The most widely used distribution in the reliability engineering is exponential distribution. This is defined as:

- is the scale parameter, in reliability it is known as constant failure rate of an item

- is the time

Weibull Distribution

In the field for the reliability functions, this distribution is widely used. It was being developed by Weibull and is used to do the statistical analysis of failure data. The probability density function f(t), is defined as:

, are shape, scale, and location parameters respectively

For Rayleigh distribution occurs

For Exponential distribution occurs

α = 0

α = 1

Figure: Location parameter graphical representation as the location changes with the change in value of the α

Section 3-Activities of Reliability and maintainability management

Activities of Reliability and Maintainability Management

Management plays a vital role in implementation of reliability and maintainability functions within an organization. This requires managers from all the disciplines to contribute equally as per necessary requirement for the reliability and maintainability activities implementation which are essential during the life cycle phases of a product or a project.

The general management in an organization hierarchy is assigned responsibilities, which are classified as:

Manpower Supervision

Cost Evaluation

Operation Analysis

In addition to the general management functions, each stage during the cycle period requires different specific management activities at various levels. The classification of managers is based primarily as per the need of the job, which is:

Project Manager

Life Cycle Material Manager

Supply Chain Manager

Project Manager

A number of tasks lie under the job description of project manager (PM) related to reliability and maintainability perspective during concept and definition phases. The performance achieved during the In-service phase can be no better than that specified in the concept and definition phases. The specifications created during this phase are the base for all the other preceding activities. This must contain reliability and maintainability targets for the benefits of design and manufacturing in addition to the intended performance requirements.

The primary functions, actions and responsibilities of the project manager mainly relate with the following main duties:

Main Responsibilities

Definition and Terms

The foremost responsibility of the project manager is to define the terms and associated definitions which will be used during the project. There exists ample number of documentation and terminologies during life of a project. All varies slightly or substantially from each other, in such case a choice to be made for appropriate selection. Also clear understanding is required between corrective and preventive maintenance techniques.

Project Management Documentation

The preparation of the requirement specification is one of the tasks for the project manager. This particular document identifies the requirements during the concept and design phase and it is necessary to list down all the equipments and tasks which are required to be managed. Also it is important to define the time frame of each task and prioritize them according to the requirement of the project. Moreover, brief description of the role and function of the equipment is to be provided along with the major technical characteristics of it.

Performance and Maintenance Philosophy

As performance is closely related to the reliability, the capability characteristics are necessary to mention in the particular form. Consideration must be given to operate the system continuously, periodically for a short time, on only once. Capability description may vary from a single to lengthy statement. Multi-mission capability will require more extensive description. Performance capability for the system can be generalized as follows:

1. Receive 2.Transmit 3.Store 4.Detect

5. Search 6.Protect 7.Generate 8.Switch

9. Maintain 10.Test 11.Calibrate 12.Display

It is essential that the project manager to make decisions regarding the maintenance philosophy during the early stage of the project. The extent and need of such decisions has a major effect on the system both in quantitative and qualitative perspective. Lack of quantitative maintenance values may require assumptions regarding tasks required and analyzing basic features of the plan design. The theme of the philosophy is that the sum of the maintenance times for a discrete maintenance action is the sum of the individual maintenance tasks required for completion. The major tasks are classified as:

Fault localization

Fault isolation

Disassembly

Interchange

Reassembly

Alignment

Check-out

Project management must consider all of the maintenance concepts. These are mainly classified into three categories. The foremost one is the one which can be carried out at the first line maintenance and is limited. The second one normally consists of a small workshop or a mobile test facility. This allows more in depth maintenance of the equipment with the availability of necessary tools and sophisticated test equipments. The third maintenance type is called the repair depot or the manufacturer facility through which all the items can be repaired appropriately maintained.

Procedural requirement and Specification Constraints

The theme of the reliability and maintainability program is a strong preparation of the specifications and the procedural requirement from the design to the in-use stages. It is necessary that appropriate procedures to be implemented and utilize during the maintenance process. Consideration must be provided if the procedural requirements include demonstrated, analyzed or projected quantitative values. Reliability and maintainability functions and management control procedures should be considered as a part of the total management program.

There always exist some constraints during the operation of the system or equipment. These constraints not only affect operational performance but also the engineering and logistics support factors as well. These include limited availability of spares, distribution of them, availability and skill of support personnel, availability of transport and availability of test equipment.

Management Controls

In addition to the above mentioned responsibilities and management control functions, it is also necessary to maintain the field studies of equipments and their appropriate documentation along with the logistic supports. Also appropriate flow of information between the customer and the supplier is required to exist in order to facilitate the whole process.

Life Cycle Material Manager

This position responsibility mainly constitute of tasks associated with guiding the activities necessary to fulfill system or equipment management objectives. The management objectives are to obtain, operate, maintain and dispose of material as economically as possible with most efficient and effective way. The main activities comprise of engineering and maintenance management, along with the activities associated with the joint functions of the project and supply manager. In addition to that interface with the operations, finance and other subsidiary departments are also required.

Main Responsibilities

There exist a number of activities in system and equipment development, all of these have a major affect on reliability and maintainability management. The main activities that are associated with this specific position with respect to the reliability and maintainability perspective are:

Engineering services

Scientific and engineering information

Corrective and preventive maintenance

Integrated logistic support engineering and management

Configuration management

Life cycle costing

Repair and overhaul

Quality assurance (QA) and test equipment

Material storage conditions

Contracts and contract warranties

Technical data package and technical orders

Engineering drawings

Budget and funding requirements

The important aspects of these responsibilities are illustrated in detail.

Engineering Services and Maintenance

It is not possible for the manager to handle all of the reliability and maintainability related functions so in some cases it may be necessary to take assistance from other experts. Engineering services is used under such cases to obtain specific services. In addition, corrective and preventive maintenance information must be published for system and equipments. In case of complex and new equipment, the preventive maintenance schedule is provided by the manufacturer. The increase in number of parts tends to require an increase in maintenance activities, but conversely, parts have become much reliable with reduced failure rate.

Configuration Management and Life Cycle Costing

One of the main responsibilities of life cycle material manager is to ensure that all the specified system and equipment characteristics are accurately defined in the engineering documents. Configuration management begins with the specification of a base line configuration. The manager is responsible for improving, evaluating and coordinating engineering proposals related to configuration management. Another aspect deals with any type of design change. Life cycle cost consists of the acquisition plus the operational costs, at which the total expenditure for hardware, software personnel, operations and maintenance are added up. To be an effective management tool, true life cycle cost analysis must be based on sound and realistic estimates of the cost of ownership. Life cycle cost estimates are used for the selection of most economical system available for a specified task.

Quality Assurance and Test Equipment

Normally, quality assurance is the responsibility of the customer and quality control being the responsibility of the contractor. The quality assurance authority is responsible for establishing policies procedure and standards for implementation of quality control (QC) programs. Both quality control and quality assurance authorities function independently under the supervision of life cycle material manager. Some of the activities of these authorities are:

Evaluating the adequacy of the contractor’s procedure.

Reviewing the contractors compliance to procedures

Verifying the characteristics of the products

Assuring that the specification requirements are met

Correcting deficiency

Reviewing waivers and deviations

There are two aspects of test equipment with which life cycle manger involves. One aspect is the provision of test equipment for every system for the purpose of effective maintenance. The second aspect is the management and calibration of the system. The reliability and maintainability of the test equipment play a vital role as well. Most of the test equipment requires periodic inspection and calibration and thus, management of calibration program is essential.

Contracts and Contract Warranties

The process leading to the issuance of contract that incorporates reliability and maintainability begins with the identification of the requirements necessary for the completion of the project. These requirements are usually in the form of the statement of the work. The life cycle material manager (LCML) will be confronted with the following attributes in a contract which involves reliability and maintainability requirements:

Suitable methods of procurement

Reliability and maintainability requirements

Price of contracting goods services

Contract time periods and identification of milestones

Administrative aspects of contract

Contract negotiation

Warranty consideration

Proprietary right and contract clauses

In addition, contracts normally have warranty clause written in them, which normally stands for guarantee from each of the parties involved. For instance, the contractor will put up a guarantee that a system will have a demonstrated MTBF after a specified test period.

Budget and Funding Requirements

In normal practice, financial organization will call for estimates once a year, to establish the funding needs for the coming years ahead along with the estimates of the next year. The life cycle material manager (LCML) will take part into all these meetings and budgeting process as being his sole responsibility. It also includes in his job description to ensure that appropriate funding is available for all reliability and maintainability tasks, especially for demonstrating, testing and analysis.

The Supply Manager

The supply manager fits into the life cycle at acquisition, operating and the maintenance and disposal phases, His management activities starts when a product is acquired and installed, and also when plans are being made for product’s support. It is essential that engineering management documents to be translated into supply management tasks, and respond to the requirements of the final user and maintainer.

Main Responsibilities

Several of supply management tasks directly influence reliability and maintainability management. These include the following:

Initial provisioning and spares allocation

Inventory Location and inventory control

Economic order quantity

Storing, packaging and shelf life

Transportation

Contract clauses

Supply policy and disposal

Initial provisioning and spares allocation

Initial provisioning is carried out by a number of technical persons, who normally belong to the supply department. Their main responsibility is to provide spares for an initial operating period for the equipment. Initial sparing involves three parts: the pipeline spares for repairable items, long lead-time spares, and a certain period of supply of non-repairable items to keep equipment in operation while the in-use spare support is being established. The factors that mainly influence sparing are failure rates, utilization rate, repair-line repair functions, transportation times, operating locations and spare costs. All of these tasks are directly related to the reliability and maintainability management.

The most important task is to allocate the most effective spare quantity for each location. Allocation must be taken into consideration as described follows:

The field experienced reliability and maintainability of each unit

The location and environment of each unit

The period of operation of each unit, if different

The difference in operation of each unit, if applicable

The confidence level of failure identification at the spares level

The required availability, procurement lead time and delays

Inventory location and inventory control

Important consideration is required to be given to the distribution of spares and their location as to make sure there in time availability when required. These are not always located at one single location. If the equipment is being installed across the country or in some cases in other countries, spares are located normally in a single location or holding depot, and the shipping is done as per the necessary requirements. The choice of spares location must be based on the spares requirement and the level of maintenance which is required to be carried out. In addition, the accessibility of the site and the distance from the spare location to the maintenance site is also important. In case of remote location, spares are stored near the location in order to save time in transportation.

Another important aspect is of appropriate control of inventory. In order to efficiently control inventory, the supply policy must be equipment or system oriented rather than commodity oriented. In present, there are also a number of systems which are utilized for inventory control. These systems use a unique coding system for the identification of each spare.

Economic Order Quantity

One of the major responsibilities of the supply manager is to reduce the cost. This is achievable by using the concept of economic order quantity "EOQ". This can be calculated as follows:

where;

is the order cost

is the inventory cost

D is the annual demand for an itemD:\Master in Engineering Management\Winter-2013\EMP5103-Reliability, Quality & Safety Engineering\Final Report - EMP 5103\EOQ.gif

is the priority factor

Figure: Relationship between inventory and order cost

This relationship applies particularly to large quantities of common items rather than for high value items. Also the priority factor is a scaling factor which expresses the importance of the spare to the operation.

Storing, packaging and shelf life

The reliability of parts is greatly influenced by how the stores and maintained. Also, the ease at which stores can be withdrawn and located from a depot influences maintenance downtime. There are normally two classification of store: (1) general, (2) dedicated.

Before any storing is undertaken three tasks must be carried out: (1) supply management must insist on a supply number for each item, (2) decide the packaging required for each item, and (3) assign a code to all shelf life sensitive items. The identification of proper packaging also has great influence on reliability. It is not only important for storing but also essential requirement for shipping purposes as well. Shelf life record keeping is also one of the major responsibilities. A unique shelf life code is being assigned to the item, which expresses the anticipated shelf life and indicates if such item requires special handling or packaging.

Supply Policy and Disposal

The development and implementation of supply policy which is in line with the reliability requirements must be a joint management project of supply and life cycle managers. This policy should incorporate general statements which cover initial provisioning for specified, reliable parts, the identification of shelf-sensitive items, the description of items with their reliability codes in the catalogue and interfacing with the life cycle manager on technical decisions.

Furthermore, the disposal of unnecessary items requires consideration from the supply manager in the area of reliability and maintainability management. The disposal of the equipment or an item which is no more required or has become obsolete may be destroyed or sold to the other party, as per requirement. This decision must be taken after discussing with the all concern authorities.

Section 4-Strategic value of reliability and maintainability Management

Reliability and maintainability management must be given importance and should include in corporate strategy as a part. The main focus and efforts are put together to improve quality up to a certain level in order to achieve customer satisfaction, which is possible only through reliable system. Thus, it is important to bring into notice of higher management that reliability and maintainability areas are taken into consideration for higher performance.

It is also evident that costs related to any system can easily be breakdown into appraisal, prevention, internal and external costs. The costs related to reliability, availability, and maintainability can also be classified into these four categories.

It is obvious that the external cost constitutes of a major portion of the cost as it directly impacts on the customer and can lead to loss of customer good will. The effect of such cost on reliability is quite apparent from the following case:

"Ford Motors suffered irreparable loss of customer goodwill from the massive recall of Firestone tires that were used on its popular sports utility vehicle – Explorer (Taylor, 2001). At that time, it was treated as a pure quality issue but one cannot deny the fact that it also had strong connection with reliability issues. The vehicles were not dependable and had higher maintenance costs. Also there were concerns regarding safety and customers worried about possibility of accidents and how to avoid them. While the quality implications were widely publicized, a major concern that was overlooked was the perception of motorists on the reliability of these vehicles. So, quality and reliability are intertwined and it is often difficult to draw the line."

This problem exposes the increasing risk of new management strategies such as supply chain management. In continuation, in order to maintain quality and reliability standards, special care to be taken in cases when a manufacturer deals with different vendors to supply parts for its product manufacturing. In order to attain customer satisfaction and good will, high reliability, availability and maintainability standards are maintained during the manufacturing processes.

The main perspective and goal of reliability and maintainability management (RMM) can be defined as follows:

"To design, operate, and improve the reliability and maintainability of a business and operations system to achieve lasting organizational effectiveness and competitiveness."

Models for reliability and profitability assessment

There are several possible ways to educate and bring attention of higher management to the strategic value of reliability and maintainability management. These are classified as "Models for reliability and profitability assessment".

Root cause analysis (RCA)

RCA is considered to be a very important terminology in the reliability perspective. It is necessary to understand the root causes of any problem in order to avoid future occurrences and transfer of information gained in operation to design phase for redesign purposes. The purpose of this practise is to avoid repetition. Root cause analysis can be likened to the Fishbone or Ishikawa diagram in which the problem causes are grouped into four categories:

Manpower

Method

Machine

Material

This classification is comprehensive and can cover problems that may be identified with a particular process reliability, availability, and maintainability. Then the highlighted causes are quantified in terms of labor hour, energy requirement, material scraps, etc., and the potential costs estimated. The following figure clearly mentions the application of cause-and-effect diagram to diagnose an unreliable system.

In cause-effect-diagram the causes are grouped together according to the four classifications as suggested in the Ishikawa diagram. To illustrate, the causes as a result of Methods include poor preventive maintenance policies, equipment replacement policies and misdiagnosed equipment failures. Manpower problems arise when failure rate is greater than service rate and the service facility is unable to handle the amount of request it is receiving. This analysis highlights areas and causes to the higher management which lead to the unreliable system and require prior attention.

Higher management pays substantial attention when cost is provided associated with each cause. The potential costs help them to pay deep and thorough attention to reliability issues. Management normally sets targets based on monthly, quarterly and annual goals. These targets are normally in terms of production rate such as how many units of items to produce per hour or per day. In order to attain the set goal, it is important aspect to know the process capability and if the process falls short, then the reasons how to manage this.

Figure: Cause-and-effect diagram for unreliable system

This analysis is incomplete to some extent as it did not cover the lost sale; however it provides higher management sufficient knowledge to work with. The lost sales also include those customers which are dissatisfied and moved to the competitors. The main priority is to recover these customers.

Failure modes and effects analysis (FMEA)

Failure mode effect analysis also considered a major function in the reliability literature like RCA. FMEA highlights issue related to problems when the process is unable to achieve targets. The aim is to identify the sources of the process problems by breaking the process into its sub-components with the intention of isolating the problem. This approach involves statistical data collection especially with relation to the frequency of sub-component failures and the cost of such failures. FMEA use the same principle as the Ishikawa diagram and relate the costs to manpower, material, method and machine problems. This process mainly pin points inability of achieving process capability.

This analysis helps higher management to understand the importance of reliability to attain strategic targets.

Reliability, Availability and Maintainability (RAM)

In field of reliability several techniques are used, reliability availability and Maintainability are among the important functions of reliability and maintainability management. RAM is basically an engineering tool that is useful in evaluating the equipment at the different stages in the design process. It addresses operations and safety issues and aims to identify areas within the system or process where significant improvement is required. It basically achieved through redesigning of the system to attain continuous improvement. The prior objectives of RAM are multifaceted and comprise of identification of failure modes which require improvement to protect the workers safety and people associated with the process. It enhances system reliability, and focuses on achieving continuous improvement through re-evaluating and proposing changes in the existing system to improve safety and reliability of the process.

RAM analysis is usually done using a reliability block diagram which identifies the critical functions of the system. The required Information for the reliability block diagram is received through industry standards or judgment of engineering and maintenance experienced personnel. By using the appropriate information, performance metrics such as the likelihood of failure, equipment downtime, and availability are obtained. The quantitative data obtained through this analysis is used to cost the impact of equipment failure and downtime on organizational effectiveness and performance. This type of information is important to the higher management in assessing how well its organizational processes are able to respond to the needs of the market.

The information and knowledge of the role of RAM in achieving organizational mission and goals makes it more practical for top management to understand the importance and necessary requirement of reliability and maintainability management. This results in clear understanding of the face that RAM is essential essence for the organization in order to be competitive in the market.

Section 5- Developing Organization-wide reliability and maintainability management

After the acceptance of the fact that reliability and maintainability management contribute to organizational competitiveness, actions plans and support frameworks are formulated by the management to support its role within the organization. An organizational cultural change is required both in attitude and perception for implementation of this critical function. Therefore, the organizations in which total quality management programs already established are better positioned to benefit from company-wide reliability and maintainability management.

The main issues that are required in order to develop organization-wide reliability and maintainability management are as follows:

Team Work

To resolve reliability and maintainability issues efficiently team work is necessary requirement. The appropriate team work acknowledges the fact that reliability and maintainability practices and functions are not limited to one function or group of analysts or engineers but reside throughout the organization. Team members should consist of engineers and personnel from each department including supply chain, thus forming successful cross-functional teams. The group of people who are part of the team should have sufficient authority in order to implement these functions appropriately. It is also essential requirement that higher management to be the part of this team as well.

The presence of higher management will enable the team to acquire all the necessary funding and resources to react actively and timely in solving critical system problems.

Continuous improvement

Reliability and maintainability management is not a project but a continuous ongoing process. In past practices, reliability was checked only at the design stage of the system or equipment. Recently, it was considered and honoured as an ongoing process with strive to continuous improvement. It is to the best interest of an organization to ensure that the product or process is at its best level at all times. This is only achievable through continuous improvement to reliability and maintainability functions.

Higher management commitment

Higher management personnel’s involvement and commitment are the basis to ensure that reliability and maintainability management acquire the adequate attention, as required. Higher management take necessary actions and plans to ensure that all the support and resources are available to support company-wide initiatives in reliability and maintainability aspects. The dedicated commitment of management personnel’s is the key to success in this field. As the management personnel takes keen attention in this field, all other connected parties will view reliability and maintainability as a core and necessary part of organizational strategy.

Supply chain participation

In today’s fast growing economy it is not possible to strive for perfection without good knowledge and implementation of supply chain. Almost all the organizations today acquire and implement essential strategies to minimize inventory, focus on increasing value to customers at optimum cost, and also on rapid response to market needs.

In order to serve customers in the best possible way, flow of information from top to bottom is a dire need. In time information sharing not only helps to identify the problems in reliability functions but also help to formulate action plans to cope up with these problems in well mannered way. These problems might be related to areas such as manpower, machine, material and methods.

Justifying reliability management

Reliability and maintainability management also have potential impacts on organizational processes and performance. The areas which have direct impact are productivity, quality, availability, and costs. Productivity is among the most important operations for an organization. If the process or system is unreliable then it will ultimately lead to decline in productivity and correspond to customer incomplete demands. Similarly, an unreliable process will never produce high quality products as per the requirements. All these factors lead to quality errors, scrap of material and rework, increasing substantially cost factor and loss of customer goodwill. This information is required to be circulated to the entire organization in order to attain the best results.

Enterprise reliability data management (ERDM)

There is a need to consolidate the reliability data of all the items and processes. The requirement of this process is to ensure that flow of information is available to everyone on similar grounds. This also helps in solving problems in teams and saving of considerable time.

The ERDM system benefit from the growing focus on enterprise resource planning (ERP) where a data bank is made called central warehouse. The sole purpose of this system is to consolidate the information at one place instead of keeping islands of information in different functional areas. Members from all departments are linked to this data base and have excess to use data mining techniques to obtain critical reliability information and data on a timely basis.

Customer satisfaction

System reliability not only smooth line the operation process but also ensures production of quality products. In other words, reliability can be counted for as customer satisfaction tool.

Reliability management is considered one of the dimensions of quality management. Electro-mechanical systems with high failure rate and long maintenance times create a lot of unsatisfied customer. Reliability and maintainability management is therefore key perspective of quality design and customer satisfaction. The fact that reliability and maintainability are measure of customer satisfaction helps in increased focus of all concern authorities in maintenance and reliability fields.

Organizational survival

Reliability management is the main base to organizational survival. In today economy the survival of every organization strongly depends on reliable systems and quality products.

Both of these are the main measures of customer satisfaction and marketplace. An unsatisfied customer will not be a loyal and patronizing customer and thus results in loss of market share. These aspects will ultimately have strong impact on organizational image in the market and company’s survival.

Section 6- Reliability and Maintainability Allocation

In order to meet with the overall specified reliability and maintainability of the system under consideration; the best practice is to set reliability and maintainability goals for all of the subsystems. Similarly these reliability and maintainability targets are then allocated to the components of these sub-systems. By doing this allocation process the overall reliability and maintainability of the system will be achieved automatically.

There are number of reliability allocation techniques which are used for the systems reliability allocation to bottom level. The efforts are put together in order to define these in detail.

ARNIC method

This method is primarily based on component constant failure rate. The following assumptions are made:

System components form a series configuration. The failure of any of the components will result in the series system failure.

Component failures are independent.

Series system reliability at time "t" is given by:

Where;

k is the total number of components in the series system

For constant failure rate, the ith component reliability at time "t" is given by:

In terms of system reliability, Rss(t) or , reliability allocation for an overall requirement is carried out by appropriate procedure. Two types of allocation approaches are used in this regards:

Failure rate allocation based on system failure rate requirement

Allocation based on system reliability requirement

AGREE Method

It is a complex method of allocation for system reliability. By comparing to the previous mentioned method, this technique is based on complexity of sub-systems instead of subsystem failure rate. In addition, AGREE takes the subsystem’s importance into consideration. This technique is utilized to determine each subsystem minimum mean time to failure in order to meet the system’s specified reliability.

The assumptions made in this methodology are as:

The sub-system failure rates are constant

Sub-system form a series system

Sub-system’s failures are statistically independent

The complexity of sub-systems is defined in terms of modules. In this technique it is assumed that module’s failure rates are equal. For the system to be success, contribution of each module is the same. The kth system allocated failure rate, is given by;

is the number of modules contained in the system

is the kth sub-system importance factor. (This factor is defined in terms of system failure probability for a particular sub-system, if that sub-system fails. If the value of the importance factor is equal to unity for a particular sub-system then it means that subsystem must function normally for system success. On the other hand, if the factor is equal to zero then it means that the failure of the sub-system in question does not affect the operation of the system.)

is the total number of modules contained in the kth sub-system

is the kth sub-system required operation time during system operation time "T" for

is the specified reliability of the system at time "T"

It is to be noted that in the above formula it is assumed that which is true for very small "y".

For the operation time "" the kth sub-system allocated reliability

Where;

The formula is subject to condition that importance factor for each sub-system is close to unity.

Maintainability Allocation Method

This method is used to allocate required system maintainability to its sub-systems or components. This allocation technique apportions the required mean to repair of a system to its components. The assumption is made that failure rates are constant and the repair times follow the log normal distribution. The basis of this technique is to make use of weighting factor when allocating system mean corrective maintenance time. The minimum time is apportioned to sub-system with high failure rates, and maximum time is allocated to sub-system with low failure rates. It is generally accepted that units which are frequently under maintenance consumes the least time. The weighting factor takes into consideration complexity, accessibility, fault isolation technique, environment and maintainability techniques.

The system weighting factor is defined as:

Where;

is the total failure rate of the system

is the constant failure rate of the ith component

is the ith sub-system weighting factor

m is the number of sub-systems in a system

is the active repair time of the ith sub-system

The ith sub-system allocated active repair time is:

represents the weighting factor, which is also called the unavailability contribution factor of the ith sub-system.

Chapter 3 – Conclusion & Recommendations