IRJET- Basic Study of Assembly Line Balancing

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 04 | Apr 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 2627
Basic Study of Assembly Line Balancing
Rohan Agarwal1, Devang Bagul2, Chinmay Agey3, Pratik Ayare4
1234Final Year Mechanical Students, BVCOE, Navi Mumbai, Maharashtra
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Abstract - Assembly Line production is one of the best-used
production systems. Th e main problem of Assembly Line
Balancing that is often faced by the industries is the
minimization of the number of workstations & cycle time and
maximization of workload smoothness and work-relatedness.
It is used to assembling quickly large numbers of a uniform
product. In other words, assembly line balancing (ALB) makes
efficient flow-line systems available for low volume assembly-
to-order productionandenablesmodernproductionstrategies
like mass customization. Assembly lines are the most
attractive means of large-scale production. Aftertheinvention
of the assembly line by Henry Ford, many developments have
been further taken place in productionsystemswhichchanged
assembly lines from strictly paced and straight single model
lines to a more flexible system with includes intermediate
buffers. Ford was the first person to build factories based on
this concept. In this research paper, a basic study is done on
assembly line balancing methods. The design ofassemblylines
is an important issue in modern days in manufacturing
engineering, management, and control. Simple line-balancing
problem method mainly consists of assigning tasks, necessary
for manufacture a product, to workstations such that the idle
time is minimized while the tasks are satisfied.
Key Words: Assembly, workstations, feasible, precedence,
constraints, unpeace, stochastic
1.INTRODUCTION
Modern production systems are characterized by
short product life-cycles, high level of automation, the
emergence of new manufacturing equipment and
technologies, and high investment. Assembly is a key to
success to the production activity; thus, it is often necessary
to develop assembly lines. Assembly lines are mainly
characterized as production systems that include serially
located workstations in which operations or tasks are
continuously processed. They are employed in many
industries like the automobile, electronics, etc. where the
objective is to produce a large series of similarproducts.The
design of assembly lines is an important issue in
manufacturing engineering and management, Askin and
Standridge (1993), Dolgui and Proth (2010). The balancing
of workstations is the most interesting performance index
for assembly line design. The simple line-balancing problem
consists of assigning tasks for assemblinga productto work-
stations (or the number of stations, cycle time, cost) is
minimized and precedence constraints between tasks are
satisfied.
Salveson (1955) has suggested a linear program to
describe all possible tasks for an assembly line. There is no
constraint on task splitting and so it may generate infeasible
solutions. Bowman (1960) added a ‘non-divisibility’
constraint by using a zero-oneintegerprogram.Anassembly
line balancing problem can also be modeled with a tree
where each arc represents a station and each path
corresponds to a feasible balancing solution, see Jack-son
(1956).
In Wee and Magazine (1982), based on the bin
packing algorithms are suggested. There are also dedicated
heuristics, for example, the ranked positional weight (RPW)
algorithm, Helgeson and Birnie (1961):first,assignthetasks
which have long chains of succeedingtasks.Thelengthof the
chain is measured either by the number of successor
operations or by the sum of the operation times.
Kilbridge and Wester (1961) have suggested a
method which is based on the graph presentation of
precedence constraints. Tasks are further assigned layer by
layer because there are no precedence constraints between
tasks of the same layer of a graph. In the past, assembly lines
were developed for a cost-efficient mass production of
similar products.it makes efficientflow-linesystemavailable
for low volume assembly order production and enables
modern production strategies like mass customization. In
this manufacturing process,interchangeablepartsareadded
to a product in a most suitable sequential manner tocreatea
finished product. Assembly Line Balancing is defined as
assigning the tasks to a minimum number of workstations
for a given cycle time.
Assembly line balancing is mainly used to achieve the
following objectives:
 minimization of the number of workstations;
 minimization of cycle time;
 maximization of workload smoothness;
 maximization of work relatedness.
Due to assembly line balancing, there isa suddendecreasein
the costs of production, lower prices ofmanufacturedgoods,
better competitiveness of enterprises, and better
exploitation of the market’s potential.
2. MAIN TYPES OF ASSEMBLY LINES
There are many types of assembly line systems,
which commonly include classic, intermittent, automated,
and lean manufacturing models. These assembly line

systems are used for making different types of products.
Assembly lines have few shared characteristics. Figure 1
illustrates the kinds of assembly systems. The types of
assembly lines are as follows:
1. Single Model Assembly Line
Single model assembly line is a type of assembly line in
which assembly workers work on same kind of products.
2. Mixed Model Assembly Line.
In mixed-model assembly line, it is the practice of
assembling several models of a product on the same
assembly line without changeovers and then sequencing
those models in a way that smoothest demand for upcoming
components. Setup times between models can be reduced
enough that intermixed model sequences can be assembled
on the same assembly line. In spite of the many efforts to
make production systems more versatile, this usually
requires homogeneous production processes. The objective
of this type of assembly line is to smoothen the demand on
work centers, manufacturing cells or suppliers and thereby
reduce inventory, eliminate changeovers, improve Kanban
operation. It eliminates difficult assembly line changeovers.
The Mixed-Model Assembly Line (MMAL) is complex to
balance where several types of the products are assembled
on the line simultaneously which considerstheshapeofline.
3. Multi Model Assembly Line
Multi-product production delay withprocessmanufacturers
where single or multiple components run through a
processing line which delivers end items and finished
products. Serial or Lot control forcomponentsandenditems
are available, as is a variety of costing and yielding methods.
Fig. 1. Assembly lines for single and multiple products.
Assembly line balancing relates to a finite set of work
elements or tasks, where each have an operation processing
time and a set of precedence relations, which specify
ordering of the tasks. One of the problems in organizing
mass production is how togroupwork taskstobeperformed
on workstations so as to achieve the optimized level of
performance.
Line balancing helps to allocate equal amounts of work to
the various workstations along the line. The fundamental
line balancing assigns a set of tasks to an ordered set of
workstations, such that precedent relationsaresatisfiedand
overall performance is optimized. The aim of assembly line
balancing problem is to assign activities to stations in
accordance to various precedence relationships while
performance is optimized. According to Ghosh and Gagnon
[2], two main types of measurements have been used in the
ALBPs. The first one is technical measurementssuchas cycle
time, balance delay or total idle time, and minimization of
number of workstations. The second one is economic
measurements like profit maximization and cost
minimization.
4. Peace and Unpeace Assembly Line
In peace assembly system, a fixed time value restricts the
work content of stations. Assembly lines withthis natureare
called paced, as all stations can begin with their operations
at the same point in time and pass on work pieces at the
same rate. In unpeace line system, work pieces do not need
to wait until a predetermined time interval is elapsed, but
are rather transferred when the required operations are
finished. This type of line control is implemented if
stochastic and probability distributive variations influence
processing times.
Generally, assembly line balancing problem occur when an
assembly line is to be designed or redesigned. The assembly
line problem was firstly introduced by Henry Ford in 1915,
the father of modern assembly line used in massproduction.
3. WHY WE USED LINE BALANCING
Generic algorithm and fuzzy logic are used in places
that have traditional assembly line and new assembly lines
such as heuristic and U-type. Simulationmethodisoftenused
to improve parameters like productivity and to obtain high
yield.
Completion of this goal is done by considering the previous
technique which is used to locate a machine, also assignment
of employer to machine is done with the help of this. Withthe
help of line balancing, few companies are successful in the
area where 1 employer controls 2 or more than 2 machines.
Advantages of line balancing are mainly are, increasing the

rate of production, to cut short man power and idle timenear
machine. Line balancing is also used for producingmorethan
2 products at a time. In mass production system, most
important component is line balancing. It is veryusefulofthe
manufacturers who produce products in highvolume,ithelps
to complete their products fast and reduces the cost as well.
Balancing performance is the key factor in determining the
productivity level of line balancing. Assigning the tasks to
successive workstations considering some constraints and
optimizing the performance is the task of assembly line
balancing. It minimizes the number of workstationsusedina
workplace.
4. ASSEMBLY LINE BALANCING TERMINOLOGIES
The terminologies often used in assembly line
balancing are told in this section. Workstation. To perform a
given assigned task a particular location is there, which is
workstation. Usually,a workstationisaccustomedbyonly one
operator.
Several operators also work on a workstation, e.g.
automobile production line. Minimumrationalwork element.
Minimum work unit in the assembly line after which work
cannot be divided. In an aircraft assembly, fixing engines, fuel
tank, wings etc., are some of the examples of minimum
rational work element. Cycle time. It is the maximum time of
individual workstations. Cycle time = (Production time per
day/Output per day). For e.g. A firm produces bicycles at the
rate of 420 bicycles per day. Time taken to produce one
bicycle is 420 minutes.
To get the cycle time in seconds, multiply the
production time by 60. Therefore, the calculations are as
follows, (420*60)/420 = 60 seconds. Efficiency = (Sum of all
task times)/(Actual number of workstations*cycle time).
BENEFITS OF ASSEMBLY LINE BALANCING
Two types of benefits are obtained from assembly
line balancing. Technical benefits – Reduction in the number
of workstations for a given number of cycles.
Cycle time is also reduced for the given number of
workstations -Balance delay is minimized. -Total idle time is
reduced. -Overall line length is reduced.
The objective of line balancing is to distribute the
task to different workstations and it aims at bringing the
workstation together to achieve optimization in the time
required, number of workers required etc. Reduction in the
delay is another important factor in line balancing. Buffer
time is also reduced which helps in better utilization of
machines in the workplace. Aims of study are as follows: -
 Improvement in productivity and decrement in
production cost.
 Figure out the minimum number of workstations.
 Elimination of bottleneck by locating and identifying
them.
 Determination of different machinery required.
 Equal distribution of workload among workers.
 Optimization of production functionsbothmanually
and automatically.
 Minimization of idle time and buffer time.
REFERENCES
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