An
assembly line is to be designed to operate 11.9 hours per day and
supply a steady demand of 510 units per day. Here are the tasks and
their performance times:
Explanation:
TASK  PRECEDING TASKS  PERFORMANCE TIME (SECONDS)  TASK  PRECEDING TASKS  PERFORMANCE TIME (SECONDS) 
a  —  36  g  d  15 
b  —  48  h  e  48 
c  —  40  i  f  20 
d  a  10  j  g  10 
e  b  28  k  h, i  60 
f  c  20  l  j, k  15 

Required: 
(a)  What is the workstation cycle time? 
Cycle time  seconds per unit 
(b)  What is the theoretical minimum number of workstations? (Round your answer to the next whole number.) 
Minimum number of workstations 
(c)  Assign tasks to workstations using the longest operating time. (Leave no cells blank  be certain to enter "0" wherever required.) 
Work station  Task  Idle time 
I  ba  
II  ced  
III  hfg  
IV  ik  
V  jl  

(d)  What is the efficiency of your line balance? (Round your answer to 1 decimal place. Omit the "%" sign in your response.) 
Efficiency  % 
(e)  Suppose demand increases by 10 percent. How would you react to this? Assume that you can operate only 11.9 hours per day. (Round your answers to the nearest whole number.) 
Reduce cycle time to seconds per unit. Another option is to work minutes overtime. 
Explanation:
(a):
(b):
(c):
Total task time T = 350
(d):
(e):
C = production time per day/required output per day 
C  = 
Production Time Per day (in seconds)
 = 
11.9*(60*60)
 =  84 seconds per unit 
Required Output per day  510 
(b):
N_{i}  = 
T
 = 
350
 =  4.17 → 5 work stations 
C  84 
(c):
Work station  Task  Task time  Idle time 
I  ba  4836  0 
II  ced  402810  6 
III  hfg  482015  1 
IV  ik  2060  4 
V  jl  1015  59 

(d):
Efficiency  = 
T
 = 
350
 =  0.833 or 83.3% 
N_{a}C  5(84) 
(e):
Reduce
cycle time to 76 seconds per unit. This produces (11.9 hours)(3,600
seconds per hour)/76 seconds per units = 564 units. Another option is to
work 71 minutes overtime (11.9 × 10% = 1.19 hour or 71 minutes). There
are many other options possible that are combinations of these two
options.
