The document discusses assembly line balancing which aims to arrange individual tasks across workstations so that the processing time is approximately equal at each station. Key points include: - Tasks have a required sequence (precedence constraints) that cannot be violated. - The production rate needed must be met within these constraints. - Terminology defined includes work elements, total work content, workstation times, cycle time, and balance delay. - The largest candidate rule is presented as a method where tasks are assigned in descending order of time to the first station that does not exceed the cycle time while respecting precedence constraints.

1. Assembly Line Balancing
Introduction to Industrial
Engineering

2. The Line Balancing Problem
 The problem is to arrange the individual
processing and assembly tasks at the
workstations so that the total time
required at each workstation is
approximately the same.
 Nearly impossible to reach perfect
balance

3. Things to consider
 Sequence of tasks is restricted, there is
a required order
 Called precedence constraints
 There is a production rate needed, i.e.
how many products needed per time
period
 Design the line to meet demand and
within constraints

4. Terminology and Definitions
 Minimum Work Element
 Total Work Content
 Workstation Process time
 Cycle Time
 Precedence Constraints
 Balance Delay

5. Minimum Work Element
 Dividing the job into tasks of a
rational and smallest size
 Example: Drill a hole, can’t be
divided
 Symbol – Time for element j:
 is a constant
ejT
ejT

6. Total Work Content
 Aggregate of work
elements
∑=
=
n
j
ejwc TT
1

7. Workstation Process time
 The amount of time for an individual
workstation, after individual tasks have
been combined into stations
 Sum of task times = sum of workstation
times

8. Cycle time
 Time between parts coming off the line
 Ideally, the production rate, but may
need to be adjusted for efficiency and
down time
 Established by the bottleneck station,
that is station with largest time

9. Precedence Constraints
 Generally given, determined by the
required order of operations
 Draw in a network style for
understanding
 Cannot violate these, an element must
be complete before the next one is
started

10. Balance Delay
 Measure of line
inefficiency due to
imbalances in
station times
c
wcc
nT
TnT
d
−
=

11. Method – Largest Candidate Rule
 List elements in descending order of T
 Assign elements to first station, from top
to bottom of list, minding constraints, and
not causing sum to exceed cycle time
 Continue assigning elements to stations
where each station < cycle time, largest
assigned first, until all assigned
 EXAMPLE