A Case Study On Improving The Productivity Using Ie Tools
A Case Study On Improving The Productivity Using Ie Tools
A Case Study On Improving The Productivity Using Ie Tools
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1
Department-School of Interdisciplinary Science & Technology,
International Institute of Information Technology, Pune, Maharashtra, India
2
Design Engineer, Tata Motors Tata Technologies Ltd, 25 Rajiv Gandhi InfoTech Park, Pune, Maharashtra, India
3HOD, Department-School of Interdisciplinary Science & Technology,
International Institute of Information Technology, Pune, Maharashtra, India
Email: shethbhavik23@gmail.com, tanmay.swaroop@tatatechnologies.com, rabinderh@isquareit.ac.in
Abstract: Assembly line balancing has been a focus of interest in Industrial Engineering for the last few years. Assembly
line balancing is the problem of assigning tasks to workstations by optimizing a performance measure while satisfying
precedence relations between tasks and cycle time restrictions. Line balancing is an important feature in ensuring that a
production line is efficient and producing at its optimum. The process of Line balancing attempts to equalize the work load
on each workstation of the production line. Mixed model assembly lines are increasing in many industries to achieve the
higher production rate. This study deals with mixed-model assembly line balancing and uses Yamazumi chart to break down
the work element in to the value added & Non-value added part to reduce the waste & increase the productivity.
Keywords: Mixed model assembly line balancing, Mudas, Takt time, Yamazumi chart.
5. Don‟t allow inertia to become the system‟s
1. INTRODUCTION constraint. When a constraint is broken, go back
to step one
An assembly line is a set of sequential
workstations linked by a material handling system. In a) We used line balancing technique to
each workstation, a set of tasks are performed using a achieve:
predefined assembly process in which the following
issues are defined: (a) task time, the time required to The minimization of the number of
perform each task; and (b) a set of precedence workstations.
relationships, which determines the sequence of the The minimization of cycle time.
tasks. Line balancing operates under two conditions: The maximization of workload
smoothness.
Precedence constraint: Product cannot move to
other station if it doesn‟t fulfill requires task at that The maximization of work relatedness.
station. It should not across other station because
For example, in the automobile industry, most of
certain parts need to be done before others.
the models have a number of features, and the
Cycle Time Restriction: Cycle time is customer can choose a model based on their desires
maximum time for products spend in every and financial capability Different features mean that
workstation. Different workstation has different cycle different, additional parts must be added on the basic
time and it depend upon the work of that particular model. Due to high cost to build and maintain an
station. assembly line, the manufacturers produce one model
with different features or several models on a single
Constraint is defined as anything that limits the assembly line. Under these circumstances, the mixed-
system from achieving higher performance relative to model assembly line balancing problem arises to
its purpose. Concept of TOC that every system must smooth the production and decrease the cost. Since
have at least one constraint and the existence of the demands for different models and for features
constraints represents opportunities for improvement. vary on a daily basis, the problem should be solved
every day in industry. In mixed model line assembly
TOC‟s 5-step process offers a systematic and models are launched to the line one after another.
focused process which organizations use to Two types of assembly line balancing problems are:
successfully pursue ongoing improvement: 1. Type-I problems, where the required production
rate (i.e. Cycle time), assembly tasks, tasks times,
The Five Focusing Steps and precedence requirements will be given and the
objective is to minimize the number of workstations;
1. Identify the system‟s constraint and 2. Type-II problems, where the numbers of
2. Decide how to exploit the system‟s constraint workstations or production employees is fixed and
3. Subordinate to the system constrains the objective is to minimize the cycle time and
4. Elevate the system‟s constraint maximize the production rate. These types of
balancing problems are generally occur when the
International Journal of Mechanical and Industrial Engineering (IJMIE), ISSN No. 2231 –6477, Volume-2, Issue-2, 2012
20
A case study on improving the productivity using IE tools
organization wants to produce the optimum number 3. YAMAZUMI CHART -- THE TOOL
of items using a fixed number of workstations Yamazumi is a Japanese word comprising Yama
without purchasing new machines or expanding its (Mountain) & Zumi (Building up) meaning „Building
facilities. up of Mountain”. It is a measurement of total time
taken in Minutes/ Seconds for completing all
1.1 Lean Manufacturing activities resulting in a finished product.
The use of the term “Lean”, in a business or
manufacturing environment describes a philosophy The time spent for doing any process can be
divided into two broad categories:
that incorporates a collection of tools and techniques
into the business process to optimize time, human
a) Time spent in doing Standard Job Element
resources, assets and productivity, while improving
the quality level of products and services to their b) Time spent in Muda (walking, picking,
customers. unpacking etc.)
Lean defines seven different types of waste that A standard job element is a value added activity
are tackled to minimize or eliminate them. e.g. tightening of bolt for fixing a part which may
take 6 seconds. However the time spent in walking to
They are as follows: a rack & picking the bolt and bringing to work station
which may be making 4 seconds is a non-value added
Overproduction,
activity and hence a waste, Muda.
Extra-Processing,
Over Stocking,
4. MAKING OF YAMAZUMI CHART
Excessive Motion,
The first step is to carry out a time study of all
Defects and Rework
process elements involved and record the time for
standard job element and MUDA. For example a
2. THE NEED finished product may require processes, which may
One of Automobile Company had plant capacity have time study as shown below:
of producing 60,000 vehicles/ year. Company wants
to launch the new model on same existing conveyor The next step is to put these time elements one
line. Work content of the new model is more compare on top of the other to get the total time for the
to existing model. One obvious conventional method finished product. This is what is called a Yamazumi
was to increase the number of work stations which Chart.
would have resulted in capital investment for
providing additional equipment, tools & utilities on
one hand and increase of manpower on the other
hand. So it was decided to increase the capacity by
improving the productivity. In simple terms the
production from 120 vehicle / day to 145 vehicle/day
through reducing the Takt time from 10 minutes/
vehicle to 6.8 minutes / vehicle.
International Journal of Mechanical and Industrial Engineering (IJMIE), ISSN No. 2231 –6477, Volume-2, Issue-2, 2012
21
A case study on improving the productivity using IE tools
International Journal of Mechanical and Industrial Engineering (IJMIE), ISSN No. 2231 –6477, Volume-2, Issue-2, 2012
22
A case study on improving the productivity using IE tools
result was reduction in man-hour, and consequent Efficiency & Element Utilization. (Fig. 6)
decrease of Takt Time.
40
Takt time is the time in which a unit must be 35 MAN-POWER
produced in order to match the rate of customer 30 REQUIRED
demand.
25
Figure 4 shows the unbalanced situation of some 20
TRIM LINE
station before line balancing. 15
10 CHASSI INE
100% 5
80% 0
60% BEFORE
40% Wait AFTER
20% Time
0% Walk Fig. 6 Comparison of man power requirement before and after
line balancing
GA GA GA GA GA GA Time
G1 G1 G1 G1 G1 G1
7. CONCLUSION
ST 0 ST ST ST ST ST 3
1.1 1.2 2.1 2.2 The strategy & techniques adapted at
Automobile Company were based on Toyota
Fig. 4 YAMAZUMI chart before line balancing Production System (TPS) and can be applied to other
companies especially those involved in continuous
Identify the area on which the work load is more and assembly line. After doing mixed model line
then transfer the activities to the other station. balancing by mutation & cross over operation
between team & station with considering all
Figure 5 shows the condition of the stations after constraint & precedence relationship. As Toyota
the line balancing. Production System is based on „Pull‟ the Takt Time
of the preceding station has to be the same as that of
Key Area Before After the following station The man-power requirement
Trim line 33 28 reduced from 69 to 58 only in the general assembly
Productivity
Chassis line 36 30 shop. Also increase the man-power utilization on
( Man-power
average from the 60% to 80 %.
Requirement ) Total 69 58
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[3]. CASE STUDY : PRODUCTIVITY ENHANCEMENT AT
Walk Time INDUS MOTOR CO. LTD. THROUGH FOCUSING ON
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3M‟S Muri (Over Burden), Muda (Non Value Added), Mura
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GA GA GA BEC Time
GA GA GA [4]. ”Re-balancing of Generalized Assembly Lines –
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ST ST ST
0 1.1 1.2 Engineering and Operations Management Dhaka,
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After Line balancing take consideration of the [6]. Erdal Erel & Subhash C. Sarin “A survey of the assembly
constraint regarding material movement, line space line balancing procedures”,
constrains, Station constrains, man-power
constrain002E And try to improve the Line
International Journal of Mechanical and Industrial Engineering (IJMIE), ISSN No. 2231 –6477, Volume-2, Issue-2, 2012
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