1. ASSEMBLY LINE
BALANCING
MODUL 7

2. What is Line Balancing ??
 Assigning each task to a work within an assembly
line in order to meet the required production rate
and to achieve a minimum amount of idle time.
 Line balancing is the procedure in which tasks
along the assembly line are assigned to work
station so each line has approximately same
amount of work.

3. Terms Defined
 Delay/idle time of a workstation: the difference
between the cycle time (CT) and the station time
(ST).
 Cycle time (CT): the time between the completion
of 2 successive assemblies, assumed constant
for all assemblies for a given conveyor speed.

4. Terms Defined (Cont.)
 Line efficiency (LE): the ratio of total station time to
the cycle time multiplied by the number of
workstations
 Balance Delay
 Balance Delay
 Work element: a part of the total work content in an
assembly process.

5. Terms Defined (Cont.)
 Smoothness index (SI): an index to indicate the
relative smoothness of a given assembly line
balance. A smoothness index of zero indicates a
perfect balance
 Workstation (WS): a location on the assembly line
where a work element or elements are performed
on the product.

6. Precedence Constraint
 Precedence Constraint is a restriction on the
order of execution of work elements.
 There are two conditions taht usually appear in
assembling process:
1. There is no dependency of the components in the
works
2. If a component has been selected to be
assembled, then the sequence begins to
assemble other components.

7. Precedence diagram
 Precedence diagram: a diagram that describes
the ordering in which work elements should be
performed. It shows that some jobs cannot be
performed unless their predecessors are
completed. The layout of workstations along the
assembly line depends on the precedence
diagram
 Presedence diagram symbols:
Symbol element
Relationship between symbols

8. Precedence Diagram

9. Zoning Constraint
 Allocation of work elements at the work station is
also limited by zoning constraints that
preclude or require grouping of certain elements
of the work on a particular station.

10. Line Balancing Methods
 Helgeson dan Birnie / Ranked Positional
Weight (RPW)
 Kilbridge and Wester Heuristic (Region
Approach)
 Largest Candidate Rule

11. Helgeson dan Birnie / Ranked
Positional Weight (RPW)
Step 1- Calculate the weight of the position of each
work elements.
Step 2- Sort the elements according to the weight of the
position of the largest to the smallest.
Step 3 -Calculate the cycle time.
 4. Place the working element with the greatest weight
on all the workstations do not violate precedence
relationships and time station does not exceed the
cycle time.
 5. Repeat step 4 until all the elements are placed.
 6. After forming a work station consisting of its
elements, then specify the value of efficient, balance
delay, and its smoothest index.

12. Kilbridge and Wester Heuristic
(Region Approach)
 Create precedence diagram of the problems faced.
Separate work elements in the diagram in columns
from right to left.
 2. Determine the cycle time (TC) of primes total time
working elements, and specify the number of work
stations.
 3. Place the work elements to work stations such that
the total time working element does not exceed the
cycle time. Remove elements of work that has been
placed on the list of work elements.
 4. When an element of work placement resulted in a
total time of work elements exceeds the cycle time
working elements are placed in the next work station.
 5. Repeat steps 3 and 4 until all work elements are
placed.
 6. Determine the value of efficient, balance delay, and
smoothness index

13. Largest Candidate Rule
 The basic principle is to combine the processes of
sorting operation on the basis of the largest
processing time to the smallest elements of the
operating time
 Steps:
1. Starting from the top, select the element to be
assigned to the first station, which meets the
requirements of precedence and does not cause the
total amount exceeds Tek on stretcher station Ts.
2. If there are no other elements that can be assigned
without exceeding Ts, then move on to the next
station.
3. Repeat steps 1 and 2 for the other stations until the
completion of all elements assigned.
4. Determine the value of efficient, balance delay, its
smoothness index.