Application of Lean Manufacturing in Mass Production
SystemA Case Study in Indian Manufacturing Unit
M. Kishore Kumar 1, A. John Rajan1, R. Kaja Bantha Navas1 , S.Sahaya Rubinson1
1
Department of Mechanical and Production Engineering, Sathyabama University, Chennai, India
kshrkmr48@gmail.com (M. Kishore Kumar), ajohnrajan@gmail.com (A. John Rajan)
Abstract – In the present competitive and challenging
market, industries need to improve their performance by
concentrating on their manufacturing processes. Lean
manufacturing is one of the most powerful manufacturing
control systems backed by several tools for improving
quality, productivity and profitability, for eliminating waste
and for improving process flow. Lean manufacturing can
also help in environmental pollution control, cutting down
the product cost, reducing physical effort and minimizing
product manufacturing time. This paper illustrates the
application of lean manufacturing to minimize the setup
time, cycle time of a reputed manufacturing industry in
India. A detailed description of each step of the process is
given and is illustrated the results from a case study
undertaken during the research. This article focuses on lean
manufacturing tools like value stream mapping, method
study, and its implementation. It will decrease the current
lead time by fifty percent. It also proposes and comes out
with measures to improve current operations within the
company.
Keywords - Lean
Mapping, Method Study
Manufacturing,
Value
activity from start to finish. Value Stream Maps highlight
processing time, waiting time, and material handling. [3]
The maps are extremely valuable in lean for reducing lead
times and eliminating unnecessary process steps. 5S is a
system for cleaning, organizing and maintaining a work
area to maximize efficiency and consistency and it is one
of the first major initiatives of companies that implement
lean.
The case study is conducted in a well reputed
manufacturing industry in South India, which produces a
variety of hydraulic cylinders for earth moving vehicles
for loading, unloading and objects moving applications.
They specialize in a broad portfolio of double-acting
cylinders, single-acting cylinders, telescopic cylinders and
their components for a wide range of applications.
Manufacturing of a hydraulic cylinder involves many
processes.
The problem identified here is to minimize the setup
time in friction welding process for productivity
improvement. The cylinder rod is first heated in induction
heater for case hardening to increase the strength. Due to
the high temperature the rod bends and is subjected to
turning operation for straightening. Then the rods are
passed through the induction heater for case hardening.
Later, each rod is subjected for end turning process in a
CNC machine and then to friction welding machine for
welding process. But the friction welding machine cannot
process this much of quantity in a day due to the high set
up time and machining time. So reduction of setup time
and machining time is very essential. This problem is
solved by applying lean manufacturing tools.
Stream
I. INTRODUCTION
In the current era of globalization, industries are
adopting new tools and techniques to produce goods to
compete and survive in the market. [4] Industries are
currently subjected to great challenges that are,
objectively, an adaptation to the “Global World”. With
this challenge, industries grow steadily focusing on
quality of products and services, to improve productivity
and thereby increase their profit. [5] Lean Manufacturing
assume as a revolution that has the potential to improve,
in fact, the productive capacity of any enterprise,
contributing with a set of tools and measures adopted at
present in response to the huge current crises, in a
growing number of companies, encompassing the whole
types of industries.
In the hydraulic cylinder, two components namely
cylinder piston rod and rod-eye are friction welded with
each other. The machine (model FW 30 01 0321)
manufactures cylinder piston rods of various sizes .The
welding process and welded parts are shown in figure 1.
The different processes involved in friction welding
machine are given below.
xRefer to the process sheet
xSelect the program.
xSet the V-block as per the rod diameter.
xSet the pesk as per rod eye bore diameter.
xSet the Stopper as per the Rod length.
xLoad the Rod in between the V-Block.
xLoad the Rod-Eye between the pesks.
xTake reference in manual mode.
xSwitch to auto mode and press cycle start.
xUnload the finished components.
Specific tools used in lean manufacturing, which
comprises a complete methodology and these tools are
interdependent forming a sophisticated yet effective
system known as Lean Tools. They play a vital role in any
productivity improvement event as they have a very high
rate of success also lasting improved effect. [2] The
common lean tools used are Method study,5S, Andon,
Bottle neck analysis, Continuous flow, Gemba (The Real
Place),Value stream mapping, Heijunka (Level
Scheduling), Hoshin Kanri (Policy Deployment), Jidoka
(Autonomation), Just in time(JIT) etc. [1] Value Stream
Mapping is a tool for documenting a set of processes
related to a single value stream, showing every step and
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TABLE I
TIME TAKEN FOR RFERRING THE PROCESS SHEET BEFORE THE
CHANGE
S.No
1
2
3
4
5
6
Part No
6287
6287
6287
6287
6287
6287
Operation
Time (sec)
Referring
process
sheet (min)
0:40
0:39
0:41
0:36
0:42
0:36
03:15
03:00
03:04
03:10
03:09
03:05
Total
production
time (min)
41:05
39:34
40:02
41:33
40:00
39:32
The following are the changes made in the arrangement of
process sheet:
1) Arrangement of the part numbers.
2) Arrangement of the consumer order.
3) Arrangement of the details of sheet.
Fig. 1. Welding Process and Welded Parts.
Set-up time for different parts is observed and analyzed.
Form the change over time details, the average time taken
for the production is 40 min.
The process sheet is arranged systematically by part
number, customer name and its drawing. Figure 2 shows
the existing and modified arrangement of drawing sheets
for ease of reference. The Table II given below shows the
reduced time for referring to the drawing sheet after the
changes have been made.
II. METHODOLOGY
In this research problem the methodology used to
implement lean manufacturing is Method Study and
Value stream mapping. Method study is the systematic
recording and critical examination of the existing and the
proposed ways of doing a work for developing and
applying easier and more effective methods, and for
reducing the costs. Method study enables the industrial
engineer to subject each operation to systematic analysis.
The main purpose of method study is to eliminate the
unnecessary operations and to achieve the best method of
performing the operation.
[6] By applying the main steps of Method Study like
Select – Record – Examine – Develop – Install – Maintain
(SREDIM), main problematic areas and the time
consuming activities are identified as follows:
1) Referring to the process sheet.
2) Adjustment of the V-Block.
3) Material movement.
Fig. 2. Existing and modified Arrangement of Drawing Sheets.
The time taken for referring to process sheet after the
change is about 1.16 min.
1) Referring to the process sheet
TABLE II
TIME TAKEN FOR RFERRING THE PROCESS SHEET AFTER THE
In the process sheet details about the parts (Piston rod
and Rod-Eye) are given. The details given in the process
sheet are: Serial number of the part to be welded, Detailed
CAD drawing of the part, Diameter of the Rod and RodEye (before and after welding), Length of the part (before
and after welding). The problems occurred while referring
to the process flow sheet are unsystematic arrangement,
non-availability of process sheet and difficulty in access.
The time taken for the existing process for referring to the
process and drawing sheet is taken. Table I shows time
taken for referring to the process and drawing sheet.
CHANGE
S.No
1
2
3
4
5
6
Part No
6287
6287
6287
6287
6287
6287
Operation
Time (sec)
Referring
process
Sheet (min)
Total
production
time (min)
0:40
0:39
0:41
0:36
0:42
0:39
01:35
01:20
01:10
01:01
01:15
01:16
41:10
39:59
40:10
41:12
40:15
40:16
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2) Adjustment of V-Block
TABLE IV
THE TIME TAKEN AFTER THE CHANGE IN THE ADJUSTMENT OF V-
V-blocks are used to clamp or fix the piston rod for
machining with the rod-eye. Pressure exerted by the Vblock varies from 50 bars to 60 bars. This is one of the
major parts of welding machine. The Problems occurred
during the adjustment of V-Block is listed below:
BLOCK
.
S.No
Part No
Operation
Time (sec)
1. Miss alignment of rod-eye and rod
2. Operator has to search for other similar V-block
3. Due to irregularities in dimensions clamping of rod
is difficult.
1
2
3
4
5
6
Table III shows time taken for the existing process of
adjustment of V-block
3) Material Movement
THE TIME TAKEN FOR THE EXISTING PROCESS OF THE ADJUSTMENT
OF V-BLOCK
1
2
3
4
5
6
6287
6287
6287
6287
6287
6287
Operation
Time (sec)
0:40
0:39
0:41
0:36
0:42
0:36
Referring
process
Sheet (min)
15:10
14:59
16:12
15:59
15:45
16:48
0:40
0:39
0:41
0:36
0:42
0:39
Total
production
time (min)
30:10
29:59
30:10
31:12
30:15
30:16
Material movement time is reduced by applying value
stream mapping. Value stream mapping is a lean
manufacturing technique used to document, analyze and
improve the flow of information or materials required to
produce a product or service for a customer. In this
process parts to be machined and finished parts are moved
using pallets. And pallets are moved using hydraulic
jacks. The problems occurred during the material
movement are listed below:
1. The pallets cannot easily carry the finished parts
2. Inadequate space near the machine
3. Unused things near the machine
TABLE III
S.NO Part NO
6287
6287
6287
6287
6287
6287
Referring
process
Sheet (min)
05:40
05:20
05:15
05:05
05:14
04:59
Total
production
time (min)
41:05
39:34
40:02
41:33
40:00
39:32
Table V shows time taken for the existing process of
material movement. The following are the changes made
in the existing material movement:
1. Wheels are fixed to pallets
2. Movement made easier
3. Space utilized is more
The following are the changes to be adopted in the
adjustment of V-block are as follows:
1. Standardize V- block dimension
2. 10mm milling: 10mm thickness is reduced from the
inner sides of the V-block which facilitates the clamping
of the rod.
3. New grip lines: The grip lines are once again cleared
and lined properly so as to increase the grip to hold the
piston rods properly and scraping.
Figure 4 shows pallets after fixing the wheels. The pallets
in Table VI show the reduced time after change in
material movement.
TABLE V
Figure 3 shows V- block before and after alteration. The
table IV is given below to show the reduced time for after
the change in the adjustment of V-block.
TIME TAKEN FOR THE EXISTING PROCESS OF MATERIAL MOVEMENT
S.No
1
2
3
4
5
6
Part No
6287
6287
6287
6287
6287
6287
Operation
Time (sec)
Referring
process
Sheet (min)
Total
production
time (min)
0:40
0:39
0:41
0:36
0:42
0:36
03:15
03:00
03:04
03:10
03:09
03:05
41:05
39:34
40:02
41:33
40:00
39:32
The value stream mapping takes into account not only the
activity of the product, but also the management and the
information systems that support the basic process. This is
Fig. 3. V-Block before alteration and V-Block after alteration
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especially helpful to the reduce cycle time, because one
can gain insight into the decision making flow in addition
to the process flow. Continuous flow processes for
welding and finishing are created by a cell welding and
finishing that allows the continuous stream and eliminates
stocks between processes.
Fig. 4. Pallets
after fixing the wheels
Time taken after the change in adjustment of V-block is
about 01:40 min.
TABLE VI
TIME TAKEN AFTER THE CHANGES IN THE MATERIAL MOVEMENT
S.No Part No
Operation
Time (sec)
1
2
3
4
5
6
0:40
0:39
0:41
0:36
0:42
0:40
6287
6287
6287
6287
6287
6287
Referring
process
sheet (min)
01:40
01:20
01:15
01:05
01:14
01:40
Fig. 5. Layout of shop floor before Changes
Total
production
time (min)
30:10
29:59
30:10
31:12
30:15
30:10
Change in the Layout
The existing shop floor and the plant layout are
described in fig 5. The shop floor has many machines like
lathe, induction machine, straightening, CNC and Friction
welding machine. They are arranged in inline production
method, where after machining in one machine only we
can machine in other. As shown in layout the pallets near
the friction welding machine is more and unavailability of
space. Therefore, some changes have been made for
bringing out better space availability and material
handling. Figure 6, shows the modified layout in which
the space is arranged properly in such a way that the
material movement is made easier. In the changed layout,
the pallets are arranged in such a way that operators can
work properly. Unused space and stopper block shelf are
removed from the area where it is kept and it is near the
friction welding machine. Now, the area is free and the
unarranged pallets are arranged in that area. Sufficient
area for the material movement is obtained with this
layout modification.
Fig. 6. Layout of shop floor after Changes
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like low volume, high variety and high volume, low
variety. The major reasons for the low level of lean
manufacturing were anxiety in changing the attitude of
workers, lack of awareness, and training about the lean
manufacturing concepts, cost and time involved in lean
implementation. Therefore, it can be concluded that the
manufacturing industry needs to give more attention to
implement lean manufacturing in all the key areas. Hence,
appropriate lean education, training, and research setup in
association with manufacturing industries are to stimulate
the lean awareness and technological development in all
type of manufacturing industries.
The concept of lean manufacturing is successfully
implemented by using method study and value stream
mapping. The quality of the products is improved.
Manufacturing costs and inventories are reduced.
Workplace flexibility benefits for employees and the
employers, as lean principles are implemented effectively.
The amount of workforce available gets increased when
the number of process is reduced, as a result, workforce
can be utilized in a better way.
III. RESULTS
The existing set up time was observed and analyzed.
Each activity was separately observed for different parts
(P6017, P7819, and P4147 etc.) and noted down. The
problems were identified and methods to reduce the set up
time were selected for implementation. After
implementation of the lean concept there is nearly 50 per
cent increase in the productivity. So more number of
products are can come out with least manufacturing cost.
The total no. of rods produced in a year before
implementation = 219,000
The total no. of rods produced in a year after
implementation = 234,330
Number of rods increased per year = 15,330
Cost for producing a single piece of rod initially = Rs.53.2
Cost for producing a rod after change =Rs. 49.5
Total manufacturing cost saved in a year = Rs.53,700
IV DISCUSSION
After lean manufacturing concept is applied, the shop
floor has discipline, cleanliness, good time management
and better productivity. The changeover or set-up time is
reduced by successful implementation of lean
manufacturing.
The following benefits are experienced after applying
lean tools: The company, become more profitable, more
competitive, experience fewer shortages and stock-outs,
improve cash flow, improve inventory turns, reduce
indirect costs, improve customer service, reduce queue
times, increase equipment uptime, improve machine
efficiency and level out production, utilize labour more
effectively, increase manufacturing flexibility and
capacity.
The challenges faced in the process of implementing
and sustain lean is a tedious job as the concept relates to
time, cost, interest, and involvement, the concepts that
together support the new change for development in an
firm.
REFERENCES
[1] Abdulmalek, A. and Rajgopal, J. (2007) ”Analyzing the
benefits of lean manufacturing and value stream mapping
via simulation: A process sector case study”, International
Journal of Production Economics, Vol.107, No, 1, pp. 223236.
[2] António Carrizo Moreira, Gil Campos Silva Pais (2011),
“Simple Minute Exchange of Die. A Case Study
Implementation”, Journal of Technology Management
Innovation, Vol.6,Issue 1, pp.131-141.
[3] Eswaramoorthi M, Kathiresan G.R, Prasad P.S.S,
Mohanram P.V.(2011),”A Survey on lean practices in
Indian machine tool industries.” International Journal of
Advanced Manufacturing Technology, Vol.52, pp.10911101.
[4] M. Shabeena Begam, R.Swamynathan, and J.Sekkizhar,
“Current Trends on Lean Management A review”
International Journal of Lean Thinking , Volume 4,No..2,
2013
[5] Luís Féteira Silva Vieira, “Application of Lean
Manufacturing methodologies to improve productivity:
Fedima
Tyres
case
study”
Portugal,
luissilvavieira@gmail.com
[6] Khanna O.P (2007), “Work Study”, Dhanpat Publication,
New Delhi.
V. CONCLUSION
Manufacturers are under intense pressure to find a
new ways to reduce production cost, elimination of waste,
enhance high quality of product, increase the productivity,
and better customer satisfaction. These parameters are
usually achieved through the implementation of lean
management practices in their industries. The traditional
manufacturing practices are indicated inadequate
representation in lean management. This paper presented
an important imminent into the status of lean
manufacturing implementation in mass production
system. The progress in lean implementation is snailpaced and needs to be augmented. It has a further scope to
develop focused lean concepts, which could be
implemented in other kind of manufacturing environment
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