Problem 6-19 The following tasks are to be performed on an assembly line: The wo
ID: 396962 • Letter: P
Question
Problem 6-19
The following tasks are to be performed on an assembly line:
The workday is 9.5 hours long. Demand for completed product is 900 per day.
a. Find the cycle time required to meet the desired output rate. (Round your answer to 1 decimal place.)
Cycle time ___________ seconds per unit
b. What is the theoretical number of workstations required to meet the desired output rate? (Round up your answer to the next whole number.)
Number of workstations __________
d. Balance the line using the longest-operating-time rule. (Leave no cells blank - be certain to enter "0" wherever required. Round your answers to 1 decimal place.)
e. What is the efficiency of the line balanced as in part (d) assuming it is running at the cycle time determined in part (a)? (Round your answer to 1 decimal place.)
Efficiency _________ %
f. Suppose that demand rose from 900 to 1,150 units per day. What would you do? (Round your answer for cycle time down to the nearest whole number.)
(Click to select)Reduce/Increase cycle time to ________ seconds, which may require rebalancing the line.
g. Suppose that demand rose from 900 to 1,450 units per day. What would you do? (Round your answer for cycle time down to the nearest whole number.)
(Click to select)Reduce/Increase cycle time to __________ seconds, which may require rebalancing the line.
References
TASK SECONDS TASKS THATMUST PRECEDE A 30 — B 15 A C 16 B D 20 B E 22 C F 17 D G 15 E, F H 21 G
Explanation / Answer
The precedence diagram of activities as follows :
A
B
C
D
E
F
G
H
Demand = 900 products per day
Cycle time = 34200 seconds/ 900units = 38 seconds / unit
= 30 + 15 + 16 + 20 + 22 + 17 + 15 + 21 seconds
= 156 seconds
Theoretical number of workstations to meet the desired output rate
= Total duration of all tasks / cycle time
= 156/38
= 4.105 ( 5 rounded tonext higher whole number )
THEORETICAL NUMBER OF WORKSTATIONS = 5
d)Balancing the line using longest operating time rule will be done in such a way so that :
ii) The precedence – successor relationship amongst activities shall not be broken i.e. a successor activity cannot be allocated prior allocating its precedent activity
Accordingly allocation of tasks to workstations as follows :
WORKSTATION
TASKS
TOTAL DURATION
( SECS)
IDLE TIME ( SECS )
= Cycle time – Total duration
I
A
30
8
II
B, D
15 + 20 = 35
3
III
C, E
16 + 22 = 38
0
IV
F, G
17 + 15 = 32
6
V
H
21
17
e)Efficiency of the line balanced
= Total duration of tasks / ( actual number of workstations x cycle time) x 100
= 156/190 x 100
= 82.1%
EFFICIENCY = 82.1%
Answer to question # f:
Revised demand = 1150 units per day
Total working duration in a day = 34200 seconds
Revised cycle time = 34200 seconds/ 1150 units = 29.74 seconds/ unit ( 30 seconds rounded to nearest whole number )
REDUCE CYCLE TIME TO 30 SECONDS WHICH MAY REQUIRE REBALANCING THE LINE
Answer to question # g :
Revised demand = 1450 units
Total working duration in a day = 34200 seconds
Revised cycle time = 34200 / 1450 = 23.59 seconds ( 24 seconds rounded to nearest whole number )
REDUCE CYCLE TIME TO 24 SECONDS WHICH MAY REQUIRE REBALANCING THE LINE
A
B
C
D
E
F
G
H