INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING ...International Journal of Industrial Engineering...

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –

6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME

10

STUDY RELIABILITY CENTERED MAINTENANCE (RCM) OF

ROTATING EQUIPMENT THROUGH PREDICTIVE MAINTENANCE

Mariam Altaf Tarar

Lecturer, Institute of Quality & Technology Management,

University of the Punjab, Lahore, Pakistan

ABSTRACT

Reliability Centered Maintenance (RCM) is the framework of preserving system

functions, rather than preserving physical asset. RCM is used to evaluate planned

maintenance schedule that will offers availability of equipment with both reliability and

maintainability. This paper presents ABC Automobile Company case, where planned

maintenance is possible with application of predictive maintenance strategy, which enables to

take decision of maintenance action with evidence and reduce unneeded maintenance. The

main principle of predictive maintenance is examining the important performance

characteristics of equipment to select the most indicative parameters of condition which reflects

functional failures. In proposals, vibration is selected as an important performance

characteristic of rotating components. Through vibration monitoring several mechanical

failures can be effectively predicted. Signals (such as through the use of vibration monitoring)

emanating from the condition monitoring of equipment are frequently interpretative as per

manufacturer’s recommendations, use of an expert system, or the threshold values established

through the experience of inspectors are used (Wiseman and Jardine, 1999).

The maintenance strategy adopted by ABC Automobile Company is preventive

maintenance with manually collected condition monitoring data. That data usually indicates

abnormality when actually failure occurs. This paper includes determination of the

effectiveness of existing maintenance strategy and its comparisons with other strategies with

improvement proposals. It outlines RCM analysis process and a test case of fans of paint

booth process.

This study concludes that RCM enables to evaluate planned maintenance action and

incase of rotating components the vibration monitoring technique can be effectively used in

predictive maintenance strategy. The paper reveals that the ABC Automobile Company can

INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING

RESEARCH AND DEVELOPMENT (IJIERD)

ISSN 0976 – 6979 (Print) ISSN 0976 – 6987 (Online)

Volume 5, Issue 1, January - February (2014), pp. 10-30

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IJIERD

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achieve enhanced manufacturing performance leading to competitive advantage with

successful RCM implementation through predictive maintenance.

Keywords: Reliability Centered Maintenance (RCM), Predictive Maintenance, Preventive

maintenance, Condition monitoring, Performance monitoring, Vibration monitoring.

1.2 Background Maintenance is routine recurring work, which is necessary to retain equipment in a

state in which it can perform its intended function. Maintenance is performed to ensure

equipment availability in industry so as to compete in global market. Maintenance has

changed more than any other management discipline during the past twenty years. In early

ages, the maintenance strategy was breakdown maintenance, as there was no awareness of

downtime. But with passage of time, increased complexity of machines led to the prevention

maintenance in second generation, and then maintenance strategies and objectives have

rapidly changed from preventive maintenance to condition monitoring. In this era, the

importance of effectiveness of operational equipment raised, which is dependent on plant

capacity (Raouf, 2004). So, the concluded strategy must have a balance between maintenance

cost and plant reliability.

Usually most of the industries in Pakistan follow preventive maintenance strategy or

scheduled maintenance. According to Herbaty, Preventive maintenance comprises of periodic

activities performed at predetermined time interval or after the specified amount of

equipment usage to keep it in proper working condition and to prevent it from breakdowns

(Herbaty, 1990).

In 1960s, a new concept, Reliability Centered Maintenance (RCM) evolved. Initially

RCM was used in aircraft industries, and it was oriented towards airplanes maintenance

(Dekker, 1996). RCM is a structured framework and a logical process of optimizing

maintenance resources for physical asset’s maintenance in its operating context. RCM is

focused on preserving system functions, rather than preserving physical asset. RCM analyzes

the functions, potential failures of equipment and it is a seven-review step philosophy to

evaluate “inherent reliability”, with risk management. RCM is possible with the selection of

an effective maintenance strategy that will offer “inherent reliability” of equipment (Samanta

et al., 2001).

1.3 Problem Statement In preventive or routine maintenance of equipment, catastrophic failures are still

likely to occur; maintenance may be performed more often than may be necessary; in such

unneeded maintenance there are chances of components incidental damage; assets taken off-

line often for maintenance services, and was mostly labor intensive. In ABC Automobile

Company, preventive maintenance is followed with actions of cleaning, lubrication,

tightening, adjustment, and parts replacement at specified time interval. Sometimes unneeded

preventive maintenance actions are performed, and just performed to fulfill schedule demand.

For such maintenance activities, equipment is taken off line and these activities are usually

labor intensive.

Secondly, ABC Automobile Company daily collects condition monitoring data. That

data are based on manual checking or observing. That is why data do not indicate any upper

or lower limit of any parameters. It indicates abnormality when actually failure occurs. The

pitfall of this method is the daily monitoring i.e. every 3hours that require extra manpower to

check and handle this manually collected inappropriate data.



12

In case of critical equipment, preventive maintenance activities are hard to schedule

so any other strategy can be more economical. The strategy through that may be beneficial is

the one in which maintenance is performed only when necessary and thus it will provide

better asset availability and reliability.

1.4 Objective The objective of this paper is to study predictive maintenance strategy and the

benefits of its implementation for the equipment at ABC Automobile Company, instead of

preventive maintenance. This study focuses on rotating equipment (e.g. motors, pumps,

conveyors, compressors etc.), where vibration monitoring can be implemented through RCM.

1.5 Gap Analysis In ABC Automobile Company, preventive maintenance strategy is followed on the

basis of schedule activities at the specified time intervals. So there is a margin to improve

through application of Reliability Centered Maintenance (RCM). This improvement is

possible with predictive maintenance requirements instead of carrying out routine or

scheduled maintenance. Performance parameters and other condition monitoring parameters

can be identified and analyzed to find out the root cause of failure. As these performance

parameters and other condition monitoring parameters are the indicators of equipment

condition and performance decline. So, their analysis will provide the optimum time to plan

and perform maintenance action before failure occurs. It will facilitate maintenance staff in

decision making by providing evidence.

1.6 Significance of the Research This paper is based on ABC Automobile Company existing maintenance strategy, and

its improvement proposal through RCM. For this purpose, an exhaustive and logical search of

maintenance literature is conducted, evaluated different maintenance strategies and their

comparison with each other. This comparison helps to select an appropriate maintenance

strategy for critical and non critical equipment. It will discuss implementation plan of RCM

through predictive maintenance, and also shows a test case of critical equipment to find out

root cause of the decline in performance.

1.7 Methodology The research approach is qualitative and primary data sources are used to collect data.

The method of data collection is observation (non-participant) and structured interviewing of

maintenance staff of ABC Automobile Company Ltd and condition monitoring Company.

This study primarily describes their existing situation and problems facing with preventive

maintenance strategy on account of the different opinions people have about an issue and

observations, and data analysis with proposals to improve this situation. A test case is

presented to analyze the validity of proposals to improve this situation.

2.1 Existing Condition Monitoring Data In ABC Automobile Company, preventive maintenance is followed with manual daily

condition monitoring of sheets. Few of the critical equipment’s monitoring parameters are

shown below with their standard ratings;



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Table 1: Existing Condition monitoring data

Equipment: PO Booth # 1 Exh. Fan

Sub-

Equipment Exh. Fan Spray Booth Exh. Fan Setting Room

Monitoring

Items Noise Vibra B.Con. B.Noise Noise Vibra B. Noise

B.Noise

Standard

Rating None None T~N~L None None None None None

Equipment: Top Coat Booth # 1 Fans

Sub-

Equipment Clear Coat# 2 Exhaust Fan

Setting Room Exhaust Fan

Monitoring

Items Noise Vibr.

B.

Noise

B.

Cond. Noise Vibr. B. Noise B. Cond.

Standard

Rating None None None T~N~L None None None T~N~L

Equipment: New Small Compressor

Sub-

Equipment Motor Oil Belt

I/P

Valves

Of

Tank

Air tank Compressor

Moisture

Trap of

Man

Tank

Moisture

Trap of

compressor

Monitoring

Items Noise Level Tension Open Pressure Noise

Manual

Drain

Manual

Drain

Equipment: Cooling Water Circulation System

CWP 01 A CWP 03 BA CWP 03 B

Sub-

Equipment

Pump

Bearing

Motor

Bearing

Motor

Cool

Fan

Pump

Bearing

Motor

Bearing

Motor Cool

Fan

Pump &

Motor

Bearing

Motor Cool

Fan

Monitoring

Items Noise Noise Loose Noise Noise Loose Noise Loose

Standard

Rating None None None None None None None None

Legends : OK=O,NG=X, Vibra.=Vibration, B.Con.= Belt Condition,

T~N~L= Tight~Normal~Loose, B.Noise=Bearing Noise.

In Table 1, noise, vibration, belt looseness and bearing noise of paint Booth # 1

Exhaust fan is monitored on basis of manual observation of maintenance staff, which is

attribute data and not clarifying quantitative data of these parameters. So it is not guaranteed

to predict equipment condition. Similar inspection is followed in case of new small

compressor and cooling water circulation system.

2.2 Analysis of existing Maintenance strategy With the existing way of monitoring parameters, it is unable to predict failure

accurately. The data of vibration or noise are based on manual checking or hearing. That is

why data are not indicating any upper or lower limit of these parameters. It indicates

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976

6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January

abnormality when actually failure o

every 3hours that require extra manpower to check and handle this manually collected

inappropriate data. As shown in Table 1, noise, vibration, belt looseness and bearing noise of

paint Booth # 1 Exhaust fan is monitored on basis of manual observation of maintenance

staff, which is not guaranteed to predict equipment condition. Similar inspection is followed

in case of other equipment as shown in Table 1.

When failure of critical equipment is focuse

many mechanical failures can be ignored and predict timely, in case of proper health

monitoring of rotating equipment.

2.3 Proposed Maintenance Action Plan On rotating equipment, predictive maintenance is a suit

failures of particular equipment and control proper working of the whole station. So,

machines and optimum monitoring techniques are selected and predictive maintenance can be

followed. With the help of condition monitoring of part

vibration monitoring equipment, their scheduled maintenance can be planned as per

requirement of machine.

The implementation of Predictive maintenance in addition to preventive maintenance

is possible with the following steps;

1. Classify equipment for maintenance,

2. Select RCM strategy,

3. Implementation of Predictive maintenance.

2.3.1 Classify equipment for maintenance First step in implementing RCM is to select or classify equipment for appropriate

maintenance strategy. The two methods used to select equipment are Criticality Analysis and

Selection Question method that is usually employed.

Figure 1: Classifying Equipment for maintenance


6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME

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abnormality when actually failure occurs. The pitfall of this method is the daily monitoring



haust fan is monitored on basis of manual observation of maintenance


in case of other equipment as shown in Table 1.

When failure of critical equipment is focused and analyzed then it is concluded that


monitoring of rotating equipment.

2.3 Proposed Maintenance Action Plan On rotating equipment, predictive maintenance is a suitable strategy to prevent



followed. With the help of condition monitoring of particular rotating components, through



g steps;

Classify equipment for maintenance,

Implementation of Predictive maintenance.

Classify equipment for maintenance First step in implementing RCM is to select or classify equipment for appropriate

The two methods used to select equipment are Criticality Analysis and

Selection Question method that is usually employed.

Classifying Equipment for maintenance


February (2014), © IAEME

ccurs. The pitfall of this method is the daily monitoring



haust fan is monitored on basis of manual observation of maintenance


d and analyzed then it is concluded that


able strategy to prevent



icular rotating components, through



First step in implementing RCM is to select or classify equipment for appropriate

The two methods used to select equipment are Criticality Analysis and



15

2.3.2 Comparison of Maintenance Strategies The following Table 2 summarizes the differences between a numbers of maintenance

strategies:

Table 2: Comparison of Maintenance strategies

Maintenan

ce Strategy

Maintenance

Strategy Brief Concept

Maintenance

Approach

Frequency of

Maintenance

Criteria for

initiating Maintenance

Condition

Assessment

Significance

& Techniques

needed

Results

Reactive

Repair actions are performed

after the failure

occurs and

people wait

until

equipment

fails, and then

maintenance

actions focused

to quickly

make possible

the availability

of equipment.

Fix it when it breaks

Unscheduled/ unplanned

Upon failure, work stoppage

to fix problem

immediately

Not usually

Large maintenance

budget

Unpredictable asset

availability

and

reliability

Preventive

In PM, maintenance

performed

before failure occurs,

for equipment

in which

downtime costs

more than

preventing

incipient

failure.

Schedule maintenance

Pre scheduled / pre planned

Prescribed based on failure

history or test

data.

To prevent

operation

problems that

lead to failure.

Not usually but

sometimes

manually collected

Periodic component

replacement/

repair.

Maintenance performed

more often

than may be necessary.

Assets often

taken off-line

time for

service.

Predictive

In PdM,

indicators

show the

requirement of

maintenance

actions to take. So it is a type

of maintenance

performed on the basis of

requirement of

machine.

Repair prior

to failure

when needed

Just in time

( planned)

Scheduled as

per need

Prescribed

based on

statistical

patterns in

operating

parameters.

To prevent

operation problems that

lead to failure or

reduced throughput.

Periodic

sample data

collection.

Monitoring

condition by

vibration,

heat,

alignment,

wear debris etc.

Maintenance

performed

when

necessary.

Better asset availability

and

reliability.

Condition Based

It is performed as per

requirement

and use

sophisticated

equipments to

detect signs of

imminent

failure. So

maintenance is performed

when need

arises.

Repair prior to failure

condition

based

Just in time ( planned)

Prescribed based on

statistical

patterns in

operating

parameters.

To prevent

operation

problems that lead to failure or

reduced

throughput

Continuous/

real time sensor

monitoring

and data

collection.

Monitoring

condition by vibration,

heat,

alignment,

wear debris

etc.

Maintenance performed

when

necessary.

Highest asset

availability

and

reliability.

It is an on-

line

monitoring system, and

generally

continuous.



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2.3.3 Select RCM strategy There are four components of RCM program which are,

• Reactive Maintenance

• Preventive Maintenance

• Predictive Maintenance

• Proactive Maintenance.

Predictive maintenance is an extension of preventive maintenance, but offers timely

failure detection of in-service machine, reduce failure severity and frequency, minimize

overall cost of maintenance, and improve operational safety. The selected maintenance

strategy is predictive maintenance in addition to preventive maintenance. It can be

implemented through two methods (Amik Garg et al., 2006);

1. Performance monitoring,

2. Monitoring through Diagnostic equipment.

As discussed above that, for critical components preventive maintenance is

insufficient to control failure, so any predictive maintenance technique is recommended.

There are many parameters which can be measured and analyzed to predict imminent failure

and monitor health of equipment. Monitoring through Diagnostic equipment enable us to

monitor;

• Machine vibration

• Wear debris analysis

• Infrared thermography

• Laser alignment

• Oil analysis

• Noise survey

Secondly, operating characteristics or performance parameters can help out in

detecting problems such as;

• Variation in Flow rates

• Pressure/temperature differences

• Comparison ratios

• Cycle efficiencies

• Variation in production rate

• Variation in product quality

• Efficiency, etc



Fig 2 Flowchart of Selected Predictive Maintenance Techniques

2.3.4 Implementation of Predictive maintenanceThe Predictive maintenance can be implemented in three distinct stages;

1. Detection

2. Analysis

3. Correction

In initial phase, it involves a detailed survey of the plant and its equipment. Then

critical and non critical equipment is classified and an RCM strategy is selected which is

appropriate for improving reliability and availability of these equipment. In case of predictive

maintenance, parameters are selected to monitor health of machines. Acceptable condit

(limits) are set and to collect data to record and analyze data. Detection means identifying any

abnormality in collected data of a particular parameter. It involves measuring and trend

analysis at marked points on each machine on a regular (scheduled

find out the root cause of the abnormality detected. It is basically a diagnosis of machine

problem, so that corrective action can be taken. Corrective action can be easily planned to

keep machine downtime at an absolute minimum.

alarm about developing problems. The below flowchart illustrates each step clearly;



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Flowchart of Selected Predictive Maintenance Techniques

Implementation of Predictive maintenance can be implemented in three distinct stages;


critical equipment is classified and an RCM strategy is selected which is


maintenance, parameters are selected to monitor health of machines. Acceptable condit



analysis at marked points on each machine on a regular (scheduled) basis. Analysis helps to



keep machine downtime at an absolute minimum. Its implementation’s main objective is to





critical equipment is classified and an RCM strategy is selected which is


maintenance, parameters are selected to monitor health of machines. Acceptable conditions



) basis. Analysis helps to



Its implementation’s main objective is to




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Fig 3: Flowchart for Implementation of Predictive Maintenance

2.3.5 Selection of Vibration Analysis Vibration is the dominant characteristic which exists in almost all machines and is

said to be the heartbeat of all mechanical equipment. Its information allows analysts to

become aware of technical condition of a machine and to diagnose its ailments, especially in

case of rotating equipment such as: gearboxes, fans, shafts, motors, compressors, pumps,

mixers, driers. Simply measuring amplitude and frequency of vibration helps to detect

machine problem and its root cause. Aim of vibration monitoring is to collect data

automatically and transmit it to specialist for analysis so that an early identification and

correction of potential machinery problems is possible.

When machine vibration increases beyond its acceptable limits, the usual reason in

any machine are unbalance, misalignment, worn parts, looseness, etc.

CLASSIFYING EQUIPMENTS

SELECT PREDICTIVE MAINTENANCE

CRITICAL

EQUIPMENT SELECT PREVENTIVE

MAINTENANCE

SELECT PARAMETERS TO

MONITOR

SET ACCEPTABLE

CONDITION LIMITS

COLLECT DATA

TREND ANALYSIS OF

FAULT DETECTION

CONDITION ANALYSIS &

ROOT CAUSE FINDING

REMEDIAL ACTION

PLANT SURVEY

YES

NO



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Vibration monitoring requires higher start up investment cost for instruments and skill

development of maintenance personnel, but it is in-service powerful information source for

detecting imminent failure and monitoring machine health. It is easy to record data and

transfer it to analyze, with portable and versatile instruments. It has accuracy to diagnose

problem and permits effective planning of corrective action, planned shutdown time, skilled

maintenance personnel and spare parts requirement. According to survey data of American

Society of Mechanical Engineers (ASME), upto 82 percent of malfunctions of the mechanical

equipment can be detected with the help of vibro-monitoring and vibro-diagnostic methods.

(Parida et al., 2000)

2.5 Summary In ABC Automobile Company, preventive maintenance system enables it to prevent

malfunctioning of critical equipment. In this system, condition monitoring of critical

equipment is performed through manually collected data on the basis of senses of sight,

smell, touch and hearing. For example the data of Paint booth fans just shows whether

abnormal noise exists or not. This system has limitation of actual parameter measurement and

authenticity of information.

Secondly it enables to alarm or indicate imminent failure and to take remedial action

before failure occurs. After the deep analysis with the help of RCM, it is concluded to follow

predictive maintenance system for critical equipment. In plant survey, equipment are

classified into critical and non critical categories and then proposed predictive maintenance

for critical components. For predictive maintenance, parameters are selected for each

machine, and to collect data and analyze. This analysis or trend data indicates imminent

failure and give alarms to take remedial action before failure occurs.

Predictive maintenance basically focuses on the future problem and helps to monitor

condition on-line. This on line condition monitoring helps to perform well planned

maintenance tasks and eliminates consequential losses. Through this system ABC

Automobile Company cannot perform unneeded maintenance and reduces overall

maintenance cost. To check the validity of the proposal a test case is taken of Paint Booth

process and vibration monitoring technique used on its fans to collect data to predict

imminent failure.

Test Case:

Step # 1 Equipment Selection The car paint process is important not only in aesthetic aspects of car but also it has

direct impact on the business. Car Paint quality cannot be compromised because it is an

integral feature of a business to generate repeated sales. The purpose of paint is to get

smooth, uniform and shiny coats which can withstand extreme conditions of sunlight, rain or

dust and tends to last long. So the paint booth process plays vital role to fulfill all

requirements of finishing process, as given below.

• Shiny and glamorous look,

• corrosion and rust prevention,

• Resistant to fading due to sun and ultraviolet rays,

In process of Painting and Drying Spray booth plays an important role where the

selected critical components are fans. In Painting and Drying Spray booth the vehicle is

painted through a spray gun with air channel, which works under low pressure, followed by

drying. The ceiling filter system derives air from outside of the facility, into the booth. Paint



stop filters hold paint particles which are decomposed from air. Spray booth contains diesel

burner and fan-motor units. A channel connection to units for air circul

installed on the facility floor.

The most important and critical function of a spray booth is managing its airflow

maintaining uniform velocity in unidirectional layers. The managed airflow results in two

advantages,

• Maximum efficiency of the paint sprayed in the Paint booth,

• And improved finish quality through directing overspray away from the painted

finish.

Air supply house supplies air to the booth after conditioning and filtering, minimizing

temperature variations and removing particulates that compromise finish quality.

Intake air moving across the painting operation conveys the overspray into the water

curtain and the water wash apparatus, which then works to move the water in such a way as

to trap and separate the particulate from the recycling water.

Process flow of paint booth is shown in fig 5, with sequence of operation and

sequence of equipment.

Fig 5



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motor units. A channel connection to units for air circulation is executed and



efficiency of the paint sprayed in the Paint booth,

And improved finish quality through directing overspray away from the painted


removing particulates that compromise finish quality.



articulate from the recycling water.


Fig 5: Process flow of paint booth




ation is executed and



And improved finish quality through directing overspray away from the painted


removing particulates that compromise finish quality.






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Step # 2 RCM Process Seven Questions & Answers

1. What are the functions and associated desired standards of performance of the asset in its

present operating context (functions)?

Delivery of air into the booth or circulation of it is provided by fans, having the capacity

of 360 m³ / min. In this unit air is delivered to the booth after being filtered by a pre-filter.

Additionally output air is controlled by a damper in the output air channel.

1. In what ways can it fail to fulfill its functions (functional failures)?

Table 3: Functional failures

Function Function Failure

Delivery of the air into the booth or

circulation of it is provided by fans while

meeting all quality, health, safety, and

environmental standards.

1. Unable to rotate at 1460 rpm

2. Unable to meet quality standards

3. Unable to meet health, safety, and

environmental standards.

2. What causes each functional failure (failure modes)?

Vibration is due to the repeating forces in machines which are mostly due to the rotation

of imbalanced and misaligned parts and may be due to the following,

• Looseness

• Contamination

• Oil condition

• Wear and tear

• Defective bearing

3. What happens when each failure occurs (failure effects)?

Failure may have following effects;

• Broken, deformed, corroded or dirty fan blades.

• Fan may trip

• Machine unavailability

• Unnecessary maintenance at predetermined schedules to adjust and replace parts

regardless of whether or not the machines are malfunctioning

• Quality problems when machine is running, which apparently seem functioning

normally, but actually running into trouble and may have yielded losses rework costs,

or worse still, warranty returns by customers.

4. In what way does each failure matter (failure consequences)?

Failure may have following effects;

• High Power Consumption, as machine that is vibrating consumes more power.

• Cost of lost production

• Cost of emergency spares procurement

• Cost of maintenance and additional overheads

• Delayed Shipment resulting in customer dissatisfaction

• Accumulation of unfinished goods or WIP (work in process)



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• Bad company image will be associated with shipment delays and poor quality

• Occupational hazards and human discomfort

5. What should be done to predict or prevent each failure (proactive tasks and task

intervals)?

Monitoring the vibration characteristics of a machine gives us an understanding of the

‘health’ condition of the machine. We can use this information to detect problems that might

be developing. Operating a machine until it breaks down might be acceptable if the machine

was a ‘disposable’ one. Most machines, however, are not ‘disposable’ due to their cost.

6. What should be done if a suitable proactive task cannot be found (default actions)?

Default actions are may be routine preventive maintenance at predetermined

schedules and cleaning of fan blades or allowed to breakdown.

This RCM seven Question process helps to determine the causes of system failures

and develop activities targeted to prevent them. The questions are designed to focus on

maintaining the required functions of the system and help to conclude proactive maintenance

strategy.

The answers of first four questions, which are related to functional failure, causes and

effects, are recorded in RCM information sheet as shown in table 4.

In table 5 answers of remaining question is recorded which is decision worksheet.

Decision worksheet is recorded with the help of answering question in RCM decision

diagram related to failure consequences, preventive tasks and default actions as shown in

Fig 6.

Table 4: RCM information worksheet

RCM information Worksheet Unit: Paint Booth Sr.

no Function

Component: Fans

Functional

failure Failure mode Failure effect

1) Delivery of

the air into the

booth or

circulation of it

is provided by

fans while

meeting all

quality, health,

safety, and

environmental

standards.

A) Unable to

rotate at 1460

rpm

Unable to meet

quality standards

Unable to meet

health, safety,

and

environmental

standards.

a) Looseness

b) Contamination

c) Oil condition

d) Wear and tear

e) Defective

bearing

Broken, deformed, corroded or

dirty fan blades.

Fan may trip

Machine. Unavailability.

Unnecessary maintenance at

predetermined schedules to

adjust and replace parts

regardless of whether or not the

machines are malfunctioning.

Quality problems when

machine is running, it appears

to be functioning normally, but

into trouble and may have

yielded losses, rework costs, or

worse still, warranty returns by

customers.



23

Fig 6: RCM decision diagram (V.S Deshpande et al., 2003)

Fig 7: Failure consequences summary (V.S Deshpande et al., 2003)



24

Table 5: RCM decision worksheet

RCM decision Worksheet Unit: Paint Booth

Component: Fans

Information

reference Consequence

evaluation

H1 H2 H3 Default

action

Proposed Task

S1 S2 S3

O1 O2 O3

F FF FM H S E O N1 N2 N3 H4 H5 S4 1 A

(a) Y N N Y N Y - - - - Schedule restoration

(b) N N N Y Y - - - - - Schedule On condition

(c) N N N Y Y - - - - - Schedule On condition

(d) N N N Y Y - - - - - Schedule On condition

(e) N N N Y N N Y - - - Schedule discard

Legends :

Step # 3 Selecting RCM Strategy In process of paint booth, unscheduled breakdown of critical components like fans

can cause production and other consequential losses. One of the selected critical components

is fans, in which buff deposit may cause other defects like wear, imbalance, etc. Its managed

airflow enables to get maximum efficiency of the paint sprayed while directing overspray

away from the painted finish. Predictive maintenance through vibration monitoring is

selected to keep the function preserved. The parameter of velocity is selected to monitor such

that must it be evenly maintained and balanced at 0.5mm/sec to perform proper function.

Y= Yes N= No F= Failure

FF=

Functional failure

FM= Failure Mode

H= Hidden

failure consequences

S= safety consequences

E=

Environmental consequences

O= Operational

consequences

N =Non Operational

consequences

H1/S1/O1/N1 On condition

Task

H2/S2/O2/N2

Scheduled restoration

Task

H3/S3/O3/N3

Discard Task

H4= Default

action

H5= Default

action

S4= Default

action



25

Fig 8: Flowchart for Implementation of Predictive Maintenance

PAINT BOOTH

SELECTED

SELECT PREDICTIVE

MAINTENANCE

FANS

SELECTED AS

CRITICAL

SELECT PREVENTIVE

MAINTENANCE

VIBRATION MONITORING

SELECTED

ACCEPTABLE LIMIT 0.5

mm/sec

COLLECT DATA

TREND ANALYSIS OF

FAULT DETECTION

CONDITION ANALYSIS &

ROOT CAUSE FINDING

REMEDIAL ACTION

PLANT SURVEY

YES

NO



26

The data collected (Table 6 and Fig 9) is plotted in given below graph, and analysis

performed on these reading revealed operation at alarm level.

Table 6: Vibration readings before repair

S.no Date Amplitude Unit Alarm Level

1 15-Oct-11 0.435 m/sec 0.55

2 16-Oct-11 0.57 m/sec 0.55

3 17-Oct-11 0.56 m/sec 0.55

4 18-Oct-11 0.55 m/sec 0.55

5 19-Oct-11 0.59 m/sec 0.55

6 20-Oct-11 0.43 m/sec 0.55

7 21-Oct-11 0.55 m/sec 0.55

8 22-Oct-11 0.58 m/sec 0.55

9 23-Oct-11 0.61 m/sec 0.55

10 24-Oct-11 0.54 m/sec 0.55

Fig 9: Equipment Vibration Monitoring Trend report before repair

After trend analysis for default detection, it is found that;

• buff deposits on fan blades,

• unbalancing,

• bearings in deteriorated condition and,

• oil condition has to be inspected,

So for, the remedial action of cleaning has been performed to remove buff deposits

from blades and deteriorated bearings were replaced. Fan was then rotated and found

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

TREND DATA

TREND DATA



27

dynamic unbalanced, so in-situ balancing performed to restore proper functioning. It is

dynamically balanced at 1460 rpm and the vibration level reduced from 0.61 mm/sec to 0.5

mm/sec, as shown in graph (Table 7 and Fig 10) below.

Table 7: Vibration readings after repair

S.no Date Amplitude Unit Alarm Level

1 25-Oct-11 0.5 m/sec 0.55

2 26-Oct-11 0.51 m/sec 0.55

3 27-Oct-11 0.49 m/sec 0.55

4 28-Oct-11 0.5 m/sec 0.55

5 29-Oct-11 0.52 m/sec 0.55

6 30-Oct-11 0.44 m/sec 0.55

7 31-Oct-11 0.46 m/sec 0.55

8 1-Nov-11 0.5 m/sec 0.55

9 2-Nov-11 0.5 m/sec 0.55

10 3-Nov-11 0.49 m/sec 0.55

Fig 10: Equipment Vibration Monitoring Trend report after repair

In this way, vibration monitoring data provided very detailed assessment of fault

causes, and selected repair action performed as per need of equipment condition. Since then,

the fans are running smoothly and uninterruptedly.

CONCLUSIONS AND PERSPECTIVES

The paper highlights application of predictive maintenance strategy and the benefits

of its implementation for the equipment at ABC Automobile Company, instead of preventive

maintenance. This study focuses on rotating equipment (e.g. motors, pumps, conveyors,

compressors), where vibration monitoring can be implemented through RCM.

0.4

0.42

0.44

0.46

0.48

0.5

0.52

0.54

TREND DATA

TREND DATA



28

The comprehensive literature review is presented of maintenance, its types and the

interfacing topics. The qualitative data is collected and analyzed with determining the

effectiveness of existing maintenance strategy. Predictive maintenance is proposed in

addition to preventive maintenance, and its previewed benefits compared. To preserve

function of equipment, RCM seven question analyses performed in test case and vibration

monitoring data is collected for fan of paint booth. That data trend is analyzed and used to

identify causes of imminent damage. So, equipment is repaired before failure and reliability

is increased by eliminating root causes.

In this way, RCM helps to plan scheduled maintenance and scarce economic

resources on critical equipment having high risk of failure. The paper reveals that the ABC

Automobile Company Ltd can achieve enhanced manufacturing performance leading to

competitive advantage with successful RCM implementation through predictive maintenance.

Due to limited resources and time, the paper showed only test case of fan of paint

booth, but in case it will implemented on all critical equipment then it will further clarify the

differences and benefits of predictive maintenance strategy over other. So, it is strongly

recommended to implement this proposal and analyze the situation differences to explore

effective Reliability Centered Maintenance.

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