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CASE STUDY Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System S. K. Singh M. K. Singh Received: 12 September 2011 / Accepted: 15 September 2011 / Published online: 4 February 2012 Ó The Institution of Engineers (India) 2012 Abstract Productivity alone does not depict the overall performance of a manufacturing system. Frequent changes in the design and need for continuously improving product quality require high degree of automation and flexibility of the manufacturing system. Thus, productivity, quality and flexibility have become critical measures of total manu- facturing performance of a production system for justifying the investment. These three measures are quantitatively defined and their combined effect has been evaluated on the manufacturing performance index of the system. A mathematical model for performance index has been developed. Further the relationship among productivity, quality and flexibility has been investigated and a method has been proposed to serve as decision support to management. Keywords Advanced manufacturing system Integrated manufacturing performance index Performance measure Quality index Productivity index Flexibility index Introduction After economic globalization manufacturing organizations are experiencing a common phenomenon, i.e., frequent changes, uncertainty and unpredictability in the business environments. In order to survive the organizations are employing various techniques such as cellular manufac- turing, JIT, flexible manufacturing or computer integrated manufacturing for high production performance. The complete evaluation of economic viability of a system can not be done on the basis of only one mea- surement variable such as productivity, profit or rate of return, because it does not help in identifying specific areas that need management’s attention [1]. Researchers identi- fied three generic productivity measurement techniques. These techniques are: the multi-factor productivity mea- surement model, the multi-criteria performance measure- ment technique, and a structured participative approach to developing productivity and performance measurement [2]. Level of operational and labour productivity is greatly influenced by the level of quality of work life and can be used as a measure of performance of any manufacturing organization [3, 4]. Globalization forces the companies to consider strate- gies of quality improvement initiatives. Internal process quality and product quality performance have its impact on operational and business performance [5]. Improved pro- cess quality reduces the cost of scrap and rework [6, 7]. Attempts to improve quality will lead to a better under- standing of the firm’s processes, which can translate into lower production costs [8]. The studies on the relationship between quality performance and firm performance suggest that: (i) quality performance has a significant and strong effect on operational performance; and (ii) quality perfor- mance has a week and not always significant effect on business performance. [912] Performance of a company can be measured on the basis of productivity, quality, and profitability [13]. Voluminous work is available on quality control, but only a few are on quality measures, particularly in economic terms. Both quality and productivity should be S. K. Singh (&), Non-member BMAS Engineering College, Agra, India e-mail: [email protected] M. K. Singh, Non-member Nikhil Institute of Engineering & Management, Mathura, India e-mail: [email protected] 123 Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101 DOI 10.1007/s40032-011-0002-0

Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System

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Page 1: Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System

CASE STUDY

Evaluation of Productivity, Quality and Flexibility of an AdvancedManufacturing System

S. K. Singh • M. K. Singh

Received: 12 September 2011 / Accepted: 15 September 2011 / Published online: 4 February 2012

� The Institution of Engineers (India) 2012

Abstract Productivity alone does not depict the overall

performance of a manufacturing system. Frequent changes

in the design and need for continuously improving product

quality require high degree of automation and flexibility of

the manufacturing system. Thus, productivity, quality and

flexibility have become critical measures of total manu-

facturing performance of a production system for justifying

the investment. These three measures are quantitatively

defined and their combined effect has been evaluated on

the manufacturing performance index of the system. A

mathematical model for performance index has been

developed. Further the relationship among productivity,

quality and flexibility has been investigated and a method

has been proposed to serve as decision support to

management.

Keywords Advanced manufacturing system �Integrated manufacturing performance index �Performance measure � Quality index � Productivity index �Flexibility index

Introduction

After economic globalization manufacturing organizations

are experiencing a common phenomenon, i.e., frequent

changes, uncertainty and unpredictability in the business

environments. In order to survive the organizations are

employing various techniques such as cellular manufac-

turing, JIT, flexible manufacturing or computer integrated

manufacturing for high production performance.

The complete evaluation of economic viability of a

system can not be done on the basis of only one mea-

surement variable such as productivity, profit or rate of

return, because it does not help in identifying specific areas

that need management’s attention [1]. Researchers identi-

fied three generic productivity measurement techniques.

These techniques are: the multi-factor productivity mea-

surement model, the multi-criteria performance measure-

ment technique, and a structured participative approach to

developing productivity and performance measurement [2].

Level of operational and labour productivity is greatly

influenced by the level of quality of work life and can be

used as a measure of performance of any manufacturing

organization [3, 4].

Globalization forces the companies to consider strate-

gies of quality improvement initiatives. Internal process

quality and product quality performance have its impact on

operational and business performance [5]. Improved pro-

cess quality reduces the cost of scrap and rework [6, 7].

Attempts to improve quality will lead to a better under-

standing of the firm’s processes, which can translate into

lower production costs [8]. The studies on the relationship

between quality performance and firm performance suggest

that: (i) quality performance has a significant and strong

effect on operational performance; and (ii) quality perfor-

mance has a week and not always significant effect on

business performance. [9–12] Performance of a company

can be measured on the basis of productivity, quality, and

profitability [13]. Voluminous work is available on quality

control, but only a few are on quality measures, particularly

in economic terms. Both quality and productivity should be

S. K. Singh (&), Non-memberBMAS Engineering College, Agra, India

e-mail: [email protected]

M. K. Singh, Non-memberNikhil Institute of Engineering & Management, Mathura, India

e-mail: [email protected]

123

Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101

DOI 10.1007/s40032-011-0002-0

Page 2: Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System

expressed in monetary terms to establish a relation between

them.

Drastic changes in market demands and rapid techno-

logical development have created a need for more flexible

production system. This leads towards the use of mecha-

nized and automated equipment. At the same time there is a

need for flexibility towards the changes in the products.

These changes have to be made within a limited time and

without huge reinvestments. Thus, flexibility has become a

key factor in today’s dynamic and competitive manufac-

turing environment. However, there may be a conflict of

aims between flexibility and productivity. Strategically; the

production system should be so flexible that neither the

product nor the renewal of the process should be hindered

by ‘‘sunk’’ cost in production.

Flexibility has been defined as the ability of the firm to

anticipate, adapt or react to the changes in its environment.

Over 70 terms (types and measures) can be found in the

literature [14]. Flexibility has been classified as machine,

material handling, operation, process, product, routing,

volume expansion, production and marketing flexibilities

[15]. Process of establishing flexible production system

provide sense of greater humanization, better job condition,

motivation, job satisfaction, making decision on their own

work and generally contributing to a higher level of quality

of life [16]. Technological flexibility requires huge initial

investments and therefore a decision to acquire it is both

risky and strategic in nature. Discussion regarding flexi-

bility verses productivity must be done before any pro-

duction system is designed [17].

The decision maker has to decide an optimum level for

productivity, quality and flexibility of the production sys-

tem. It is also important to evaluate, how these three

parameters correlate with each other because these

parameters may have conflicting effects on the perfor-

mance index of the production system.

Proper evaluation of any production system relative to

these parameters requires precise measurement of produc-

tivity, quality and flexibility. Performance measurement of

a system is one of the most important engineering and

management tool for:

• Justifying the investment in integrated manufacturing

and production system.

• Continuous improvement of existing system.

• Providing an insight into where the change is needed.

• Predicting and estimating future productivity.

Literature Review

Performance prediction of advanced manufacturing system

is very essential before incorporation in the industry. Its

performance can be evaluated by three conflicting perfor-

mance parameters, i.e., productivity, quality and flexibility.

To consider these parameters in combined; their quantita-

tive measurement should be done on common scale. In this

direction some of researcher has contributed which is

presented here.

The review of literature on manufacturing system, pro-

ductivity measurement and improvement has been sum-

marized under four categories; they are operation research

(OR) based methods, system analysis based methods,

continuous improvement based methods and performance

metrics based methods. Five types of performance objec-

tives based on cost, flexibility, speed, dependability and

quality has been mentioned. It has revealed that perfor-

mance measure criteria must be driven by strategic

objectives and the measures must provide timely feedback.

Manufacturing systems often operate at less than full

capacity while producing quality product and frequent

change in design specification is required; so, the produc-

tivity is low and the costs of producing products are high

[18]. In order to reduce the cost of manufacturing, com-

panies are very much concern in effective utilisation of the

resources. Some researchers report that TPM is one such

tool to enhance equipment effectiveness and maximise

equipment output. The findings indicate that TPM not only

leads to increase in efficiency and effectiveness of manu-

facturing system, but also prepares the whole plant to meet

the challenges put forwarded by globally competing

economies [19]. The TPM model provides a quantitative

metric for measuring the productivity of individual pro-

duction equipment.

It is discovered that appropriate measurement is needed

for identifying the problems in order to improve and

increase productivity. To achieve this, it is necessary to

establish appropriate metrics for measurement purposes

[20]. Performance measurement system is underdeveloped

and under researched in small and medium enterprises [21].

Traditional performance measures are focusing into the

sub-optimisation instead of seeking into overall perfor-

mance [22]. The question of what particular performance

measures to use is a complex task, and is not being made

any easier as the number and type of performance measures

available continues to grow [23].

Overall equipment effectiveness (OEE) directly mea-

sures product quality, loss and the abilities to deliver to a

schedule [24]. Before the advent of OEE, only availability

was considered in equipment utilisation, which resulted in

the overestimation of equipment utilisation. OEE method-

ology is a proven approach to increase the overall perfor-

mance of equipment [25]. The ultimate objective of any

factory is to have a highly efficient integrated system and

not brilliant individual equipment [26]. Traditional OEE

used by the companies is inadequate, so, the managers

94 Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101

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should focus on measuring the total effectiveness of the

manufacturing system [27]. The metrics for measuring and

analysing the productivity of manufacturing operations

from the equipment level to the system level are of

increasing importance to companies seeking to continu-

ously optimise existing operations [28].

A new approach is proposed to assess the quality rate of

manufacturing system using principal component analysis.

A detailed methodology for determining the overall line

availability, overall line performance and overall line

quality is developed using overall line effectiveness as an

index of performance evaluation [29].

Cost reduction without compromising on quality has

become the motto of every manufacturing organisation, to

survive in the global market. Due to the complex nature of

most manufacturing systems, at present it is still very dif-

ficult to analyse the overall performance of a complex

manufacturing system. The goal programming, multiple

regression equations and GP technique have been used for

modeling the relationship between product quality and

control variables [30]. The influence of quality improve-

ment aspects on a firm’s productivity performance has been

examined and it was found that quality awareness, sug-

gestions towards improvement, voluntary work and train-

ing influence productivity [31]. The study on the

relationship between quality and productivity reveals that

quality improvement measures play a fundamental role in

increasing productivity [32]. The importance of supply

quality management has been stressed in the improvement

of an organization’s quality performance [33]. A total cost

equation and evaluation of the optimal ordering quantities

for a production system with quality assurance and rework

have been developed [34]. Some of the researcher advocate

to optimize the assembly tolerances for quality, and mini-

mizes the manufacturing cost [35]. Author has conducted a

review on quality management research along five main

themes, i.e., definition of quality management, definition of

product quality, the impact of quality management on firms

performance, quality management in the context of man-

agement theory and the implementation of quality man-

agement [36]. An attempt has been made to measure,

examine and determine whether there exist possible inter

relationships between the terms quality of work-life and

productivity [37].

The issue of flexibility is assuming increasing impor-

tance in manufacturing decision making. Flexibility is

important to accommodate changes in operating environ-

ment. The manufacturing systems that are flexible can

utilize the flexibility as an adaptive response to unpre-

dictable situation. A lot of work has been done to define

properly the manufacturing flexibility and provided various

methods for measuring them [38]. A critical review of

selected measures from the literature is provided and a

flexibility measure is proposed and its application is

demonstrated through a hypothetical example. Perfor-

mance of the measures and proposed measures are com-

pared [39].

With change in market trend and technological

development it is essential to have flexible production

system without any compromise with the productivity.

This necessitates the discussion regarding productivity

verses flexibility before design of production system.

Various methods for calculation of different flexibility

level, strategy for a more flexible view upon product and

process in the context of Swedish industry are discussed

[17]. A method to evaluate flexibility of product design

has been developed and a set of guidelines to guide

product architecture to a desired state of flexibility is

derived [40]. Various evaluation variables of flexibility

and factors improving the flexibility of single stage

production system with different characteristics have

been proposed. It also pointed out the characteristics of

the amplification of multistage production system as one

of the important factors affecting the flexibility and

productivity of the system [41]. An investigation has

been made to evaluate the impact of shop and workers

flexibility on different assembly cell faced with product

mix variability over a wide range of experimental con-

ditions. In this case three types of cellular shops were

considered, i.e., strict cell shops, flexible cell shops and

hybrid cell shops. Result indicates that there is no cell

shop that outperforms other under all experimental

environments. Finally the result suggests that in most

cases the implementation of only worker flexibility

resulted in the majority of improvement with respect to

the average percentage of jobs tardy [42].

In this research work an attempt has been made to give

the improved definition and quantification of productivity,

quality and flexibility in monetary terms. A relationship

among productivity, quality and flexibility has been

investigated and finally a method has been proposed to

decide whether decision maker should opt automated

production system or not for high performance of

industry.

Objective

1. The objective of this work is to identify the various

measures of performances of a production system.

2. To define the productivity, quality and flexibility and

to quantify these terms on the monetary scale.

3. Establish a relationship between productivity, quality

and flexibility and their combined effect on the overall

performance of an automated production system.

4. A case study in ball bearing plant for the validation of

the proposed model.

Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101 95

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Measurement of Variables

Here we have considered total productivity consisting of

labour, capital, raw material and miscellaneous produc-

tivity. Labour productivity includes direct and indirect

labour, material productivity includes direct and indirect

material and miscellaneous productivity is consisting of

energy efficiency, floor space reduction, increased use of

computer software, etc. In this study future productivity is

also being considered apart from past and present pro-

ductivity for the incorporation of capital intensive auto-

mated production system.

The productivity is concerned with the efficiency of

converting inputs to outputs. These outputs are expressed

in common terms, i.e., monetary terms so that they can be

added together. In this case total productivity is considered

under three different partial productivity heads, i.e., labour,

material and overhead productivity.

Productivity Measurement

Labour productivity (PL) measures labour performance

required to produce total output and is defined for a given

period of time as:

PL ¼OP

CL

Labour cost, CL ¼XL1

d¼1

cdNnd þXL2

i¼1

cini

ð1Þ

where L1 is the number of different jobs using direct

labour; L2 is the number of different jobs using indirect

labour; cd is the Wage of job d per unit time; N is the time

period; ci is the salary of job i during a time period; nd is

the number of direct labour units for job d; ni is the number

of indirect labour units for job i.

Material productivity (Pm) measures the efficiency of

raw material use and is defined for a given period as

Pm ¼OP

Cm

Material cost; Cm ¼ Co þXJ

j¼1

Cd jð Þnd jð Þ þ Cid

ð2Þ

where Co is the material ordering cost; J number of dif-

ferent parts; Cd (j) is the unit cost of direct material for part

j; nd (j) is the amount of direct material used for part j; Cid

is the indirect material cost except tools.

This measure is useful when material cost is a significant

part of the total cost.

Overhead productivity (POH) is the efficiency of all

resources except labour and material. This group of inputs

includes machines, tools, floor space cost. Machine cost

includes expenses such as energy, maintenance, repair,

insurance and property tax. As the level of automation

increases, overhead cost (COH) increases. For a given

period it is defined as

POH ¼OP

COH

COH ¼ Ct þ Cs

Tool cost, Ct ¼XM

m¼1

cd mð Þ nw mð Þþf nbðmÞg

ð3Þ

where cd (m) is the unit cost of tool type m; nw (m) is the

number of worn tools of type m; nb (m) is the number of

broken tools of type m; M is the number of different tools.

Floor space cost; Cs ¼ Cu þ Cm þ Cr þ Cið Þ Sm=St

� �

Cu is the total plant utility cost; Cm is the total plant

maintenance cost; Cr is the total plant repair cost; Ci is the

plant insurance cost; Sm is the manufacturing floor space; St

is the total plant space.

Productivity index (PI) is formed by integrating the

partial productivity measures and is used to measure the

total manufacturing efficiency. PI for a given period is

defined as:

PI ¼ OP

CL þ CM þ COHð4Þ

The Eq. 4 is similar to the productivity measure by

‘‘Craig and Harris’’ [43].

Obvious trade-offs exist among partial productivity

measures. Consider, for example, a company makes an

investment in automated machine it significantly reduces

the man-hours necessary for processing. Suppose this

increased cost of using automated machine equals the

saving in the labour cost. Although the firm’s total pro-

ductivity does not change, labour productivity would nat-

urally increase. This type of fallacy is inherent in all partial

productivity measures. Therefore, productivity index must

used for company wide management decisions.

Measurement of Quality

Quality is a measure of manufacturing performance which

indicates the degree of perfection in making products. In

this case two types of partial quality measures are con-

sidered, that is, process and product.

Process quality (QS) is the ability of processes to make

good product with a small prevention cost. The prevention

cost (CP) is the in-process inspection cost for checking and

maintaining quality before final inspection. We define it for

a given period as:

96 Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101

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Page 5: Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System

QS ¼OP

CP

Prevention cost, CP ¼XJ

j¼1

XK1

k¼1

cp j; kð ÞNð5Þ

where K1 is the number of machines except material

handling system; N is the time period; cp (j,k) is the pre-

vention cost of part j for machine k per unit time.

A reduction in prevention cost increases process quality.

Product Quality (QP) is the degree of excellence of

finished products. Product quality increases as product

defects decreases. The defects can be expressed in terms of

failure cost (CF). This failure cost may indicate loss due to

failure of finished products to meet quality standards.

Product quality for a given period is defined as:

QP ¼OP

CF

Failure cost, CF ¼XJ

j¼1

E cf ðjÞ� �

Qj

ð6Þ

where cf (j) is the failure cost of part j; Qj is the lot size of

part j

E cf ðjÞ� �

¼ cg þ cb þ cs þ ca

cg is the cost of reworking a good part because of mis-

classification; cb is the cost of reworking a bad(defective)

part; cs is the cost of scraping a defective part that could not

be restored; ca is the cost of accepting a defective part.

Quality Index integrates the partial quality measures and

may be used to measure the total quality performance. For

a given period it is defined as:

QI ¼ OP

CP þ CFð7Þ

A tradeoff exists between the two partial quality

measures. Assume, for example that tight process control

to reduce product defects raises prevention cost, but lowers

failure cost. If total output is constant, the use of partial

measures indicates a conflicting signal.

On the other hand, if the increase in the prevention cost

equals the decrease in failure cost the quality index remain

unchanged.

Measurement of Flexibility

Flexibility is a measure of manufacturing performance

which indicates a manufacturing system’s adaptability to

changes in manufacturing environments. Three different

types of partial flexibility measures are considered, i.e.,

equipment, product and demand.

Equipment flexibility (FE) is the capacity of equipment

to accommodate new products and some variants of

existing products. Equipment flexibility is measured in

terms of idle cost(CI), and is defined as:

FE ¼OP

CI

Idle cost, CI ¼ vXK2

k¼1

ð1� ukÞNð8Þ

where uk is the utilization of machine k; v is the profit per

unit time; k is the number of machines; N is the time

period.

Equipment flexibility measures the opportunity of

equipment to add value to raw materials. Equipment idle

time should be reduced whenever possible to increase

equipment flexibility.

Product flexibility (FP) is the adaptability of a manufac-

turing system to changes in product mix. Product flexibility

is measured in terms of setup cost (CS) and is defined as:

FP ¼OP

CS

Setup cost, CS ¼XK2

k¼1

CsuðkÞTsuðkÞð9Þ

where Csu (k) is the setup cost for machine k per unit time;

Tsu (k)is the setup time for machine k.

A frequently changing market demands new products

and variations of existing products. These changes in

product mix result in a shorter life cycle of product and a

smaller lot size as the variety increases. Smaller lot size

means higher set up cost. Reducing setup cost in spite of

small lot sizes is often viewed as the key to increased

product flexibility. Rapid exchange of tools and dies and

flexible fixtures are good examples of setup reduction

methods.

Demand flexibility (FD) is the adaptability to changes in

demand rate. The demand may be of two types: customer

demand for finished products and manufacturing system

demand for raw materials. Demand flexibility may be

measured in terms of inventory costs (CINV) of finished

products and raw materials. Demand flexibility for a given

period is defined as:

FD ¼OP

CINVð10Þ

Flexibility Index is formed by integrating the partial

flexibility measures and can be used as a global measure of

the opportunity of a manufacturing system to add value to

products. Flexibility index for a given period is defined as:

FI ¼ OP

CI þ CS þ CINVð11Þ

Tradeoffs may exist between different flexibility

measures. For example, assume that a conventional milling

Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101 97

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Page 6: Evaluation of Productivity, Quality and Flexibility of an Advanced Manufacturing System

machine is replaced by a CNC milling machine with a larger

capacity. Setup cost decreases but idle cost increases. For a

constant output, product flexibility increases, but equipment

flexibility decreases. If the decrease in setup cost equals the

idle cost the flexibility index remained unchanged.

Therefore, the partial flexibility concept may not measure

the total manufacturing adaptability to various changes.

Integrated Manufacturing Performance Index

Now productivity, quality and flexibility indexes are inte-

grated to form a global index that reflects these three

attributes. Productivity, quality and flexibility have some

correlation to each other, whether positive or negative.

Mass production with poor quality increases productivity

because of mere increase in total output. Quality and

flexibility, however, usually decreases because of relatively

large defects and product inventory. The use of only one

index over the others is not desirable in evaluating the

manufacturing performance as a whole. Thus, the inte-

grated manufacturing performance index (IMPI) for a

given period is defined as:

IMPI ¼ Total output Rs:ð ÞIP þ IQ þ IF

ð12Þ

where IP = CL ? CM ? COH, IQ = CP ? CF and

IF = CI ? CS ? CINV.

Model Formulation

Considering IMPI as dependent variable and PI, QI and FI as

independent variable, the multiple regressions analysis has

been conducted. The data used are collected from the

industry for a time horizon of 24 months. The required data

are total output, labour cost, material cost, overhead cost,

inspection cost, failure cost, idle cost, set-up cost and

inventory cost. From the above data Productivity, Quality

and Flexibility index for both manual and automatic pro-

duction line have been calculated (Tables 1, 2). The analysis

provided the following mathematical relationship between

PI, QI and FI for manual and automatic production line.

For manual line

IMPI ¼ �0:00215þ 0:04915 ðPIÞ � 2:55� 10�5 ðQIÞþ 0:6094 ðFIÞ ð13Þ

For automatic line

IMPI ¼ �0:004038 þ 0:070369 ðPIÞ � 1:2145

� 10�5 ðQIÞ þ 0:5457 ðFIÞ ð14Þ

Result Analysis

From Eq. 13, 14 it is clear that the productivity index has

positive regression coefficient. Although overhead pro-

ductivity of automatic line is comparatively less than that

of manual line but overall productivity is more significant.

The quality index has negative regression coefficient in

both the cases. But in case of automatic line, it is numer-

ically less. This shows that failure cost and prevention cost

is less in automatic system than manual system. The result

shows that flexibility index has positive impact on the

integrated manufacturing performance index. In the present

case product and demand flexibility of automated line is

higher than that of manual one but equipment flexibility is

less. This is because the automated line is underutilized and

its higher depreciation cost leads to higher idle cost.

Therefore, the coefficient of flexibility index of automated

line is lower than the manual line. The result may be

plotted on the graph between IMPI and any two parameters

keeping third parameter constant as shown in Figs. 1 and 2.

Table 1 IMPI for manual production system

S. no OP PI QI FI IMPI

1 824643 2.155124 112.61 0.613106 0.475301

2 848845 2.149274 120.6946 0.538785 0.42926

3 1088559 2.516993 153.7079 0.768053 0.586235

4 815538 2.141993 110.5664 0.506821 0.408333

5 863120 2.181833 117.2399 0.513069 0.413922

6 888175 2.156916 126.7554 0.541781 0.431541

7 883040 2.163932 125.2184 0.514546 0.414325

8 969653 2.351797 135.0868 0.638568 0.500347

9 901992 2.27344 127.1307 0.572075 0.455425

10 1095758 2.447866 152.8894 0.775243 0.586518

11 899691 2.317459 125.8837 0.632083 0.494677

12 1071019 2.411591 147.9104 0.827253 0.613405

13 1059121 2.427729 136.4847 0.646979 0.508937

14 870588 2.126238 109.5906 0.483904 0.392779

15 939848 2.301721 119.0284 0.629109 0.492027

16 838928 2.119372 107.2524 0.583488 0.455582

17 747193 2.073215 93.59802 0.54214 0.427795

18 829149 2.138503 104.0338 0.584112 0.456782

19 978660 2.404925 125.6303 0.642831 0.505206

20 966512 2.280623 122.7473 0.550187 0.441659

21 900671 2.393549 114.2838 0.549339 0.445056

22 792823 2.067513 100.0786 0.505035 0.404248

23 946272 2.382368 120.5442 0.63872 0.501586

24 998467 2.416893 128.7514 0.702732 0.542141

98 Journal of The Institution of Engineers (India): Series C (January–March 2012) 93(1):93–101

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Performance Prediction of Production System

In an effort to improve the performance of a production

system, computer integrated manufacturing and production

system can play a significant role. But being a capital

intensive project, the decision makers scare to incorporate

such system until its economic viability has been estab-

lished. Manufacturer does not prefer the huge investment

for long-term under uncertain environment and without

foolproof economic justification.

The study has been carried out in a bearing manufac-

turing company having both the types of production sys-

tems: manual and automated and required data has been

collected. For evaluation of overall performance index of a

system three parameters are considered, i.e., productivity,

quality and flexibility and all are measured on same eco-

nomic scale. On the basis of economic analysis, viability of

capital intensive project has been evaluated.

Finally it is observed that the values of some partial

measures such as overhead productivity and equipment

flexibility decreases because of a large initial investment

for an automated production line. The value of remaining

partial measures increase significantly, particularly labour

productivity (223.89%), process quality (201.22%), prod-

uct quality (53.75%), and product flexibility (58.71%).

These results demonstrate that an automated line remark-

ably reduces product defects, setup cost, WIP, and labour.

Since most of the partial measures increase, each total

measure also increases: productivity by 7.56%, quality by

156.73% and flexibility by 34.38%. With significant

improvement in both quality and flexibility, despite a small

increase in productivity, the IMPI increases by 27.62%.

The results shown in the Table 3 are of single obser-

vation and on the basis of 24 such observations we obtain

at the 95% confidence level the IMPI as follows:

44:85\IMPI\50:01 For manual line

57:77\IMPI\64:17 For automated line

Since the confidence interval of IMPI for automated line

is totally to the right of the upper bound of that of IMPI

for manual line and hence, there is strong evidence that

the automated line provides better total manufacturing

Fig. 2 Relation between IMPI, PI and FI when QI remains fixed for

automatic line

Fig. 1 Relation between IMPI, PI and FI when QI remains fixed for

manual line

Table 2 IMPI for automatic production system

S. no OP PI QI FI IMPI

1 2483971 2.3181946 289.1028 0.82391 0.606592

2 2556871 2.309636 318.6529 0.727362 0.5522

3 3278932 2.6994182 403.8094 1.034144 0.746319

4 2456547 2.3031265 282.4916 0.684526 0.526705

5 2599871 2.344279 299.939 0.693837 0.534427

6 2675341 2.3116013 335.5501 0.734443 0.556435

7 2659875 2.3215264 329.9274 0.696882 0.535118

8 2920768 2.5200042 351.5609 0.864082 0.642275

9 2716960 2.437048 333.574 0.775485 0.587252

10 3300618 2.617359 398.3367 1.051573 0.748765

11 2710028 2.4907636 328.6077 0.858873 0.637413

12 3226100 2.5826238 382.602 1.12433 0.781717

13 3190260 2.5968954 361.5435 0.879935 0.656044

14 2622366 2.2806594 285.4742 0.656583 0.508904

15 2830988 2.466935 311.4056 0.853572 0.632863

16 2527000 2.2749738 282.441 0.787581 0.583833

17 2250677 2.2394774 243.0012 0.728963 0.548709

18 2497544 2.3014151 270.4433 0.786205 0.584746

19 2947898 2.5811637 331.8584 0.870617 0.649753

20 2911305 2.4457513 321.7623 0.750825 0.573444

21 2712980 2.5762922 299.3798 0.748033 0.578592

22 2388125 2.2222289 261.2257 0.682342 0.521005

23 2850340 2.5582401 316.6341 0.865134 0.645185

24 3007560 2.5928381 341.264 0.951479 0.694636

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performance. This justifies the capital investment in

advanced manufacturing system to improve overall

performance.

Conclusion

The purpose of this research is to quantify and combine

three critical performance measures into one global index.

The conventional productivity measures are improved and

its index has been developed for use in IMPI. Quality and

flexibility measures are defined, quantified and an index

has been developed. These three indexes are combined

together to form IMPI which evaluate a manufacturing

system as a whole. IMPI is the primary measure of man-

ufacturing performance. PI, QI, FI and partial measures are

surrogates to the IMPI. The proposed model can be applied

in any engineering industry manufacturing variety of

products and needs implementation of automated system

for higher performance.

The study indicates that the adoption of an automated

manufacturing system improves the overall manufacturing

performance, compared with a conventional manual man-

ufacturing system. However, just because an automated

system performs better does not mean we abandon the

conventional manual system. The adoption of automated

system requires a large initial investment under a long-term

environment. Economics of the project should be consid-

ered over the project’s life cycle. The performance indexes

developed here can be useful in strategic planning since

they not only evaluate past or current manufacturing per-

formance, but can also predict the effect of capital

investment on future performance.

Scope for Future Work

The present study is concerned to quantify and combine

three critical performance measures i.e. productivity,

quality and flexibility to obtain IMPI. The evaluation of

IMPI for conventional and automated production system is

done with certain assumptions. However, this work can be

further extended as:

1. In the present study we have considered only the

labour productivity, material productivity and over-

head productivity. For calculation of total productivity,

the capital productivity should also be considered.

Because it measures the efficiency of capital invested

on equipment and building. This measure is useful in

capital intensive project. Similarly one can form

energy productivity when energy cost is a large part

of the total cost.

2. For calculation of process quality index in this case we

have considered labour and equipment cost in approx-

imate involved in inspection process on average basis.

More precise result can be obtained by using control

chart. In this case cost of sampling, cost of improving

assignable cause, cost of improving process capability

in each cycle etc. are also required to be calculated.

3. For demand flexibility we have considered only

inventory cost of finished product and WIP of product.

For better result, cost of service and risk per unit raw

material of part, back order cost of unit raw material,

back order cost of unit finished product should also be

considered.

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