An assembly line is to be designed to operate 11.9 hours per day and supply a steady demand of 510

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:

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	b-a
II	c-e-d
III	h-f-g
IV	i-k
V	j-l

(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):

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):

Ni	=	T	=	350	=	4.17 → 5 work stations
		C		84

(c):

Work station	Task	Task time	Idle time
I	b-a	48-36	0
II	c-e-d	40-28-10	6
III	h-f-g	48-20-15	1
IV	i-k	20-60	4
V	j-l	10-15	59

Total task time T = 350

(d): 

Efficiency	=	T	=	350	=	0.833 or 83.3%
		NaC		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.

The following tasks are to be performed on an assembly line:

The following tasks are to be performed on an assembly line:

TASK	SECONDS	TASKS THAT MUST PRECEDE
A	18	—
B	12	A
C	10	B
D	14	B
E	26	C
F	28	D
G	15	E-F
H	15	G

 

The workday is 8.75 hours long. Demand for completed product is 900 per day.

 

Required:
(a)	Find the cycle time. (Round your answer to 1 decimal place.)

Cycle time

seconds per unit

 

(b)	What is the theoretical number of workstations? (Round your answer to the next whole number.)

Number of workstations

 

(c)	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.)

Work station	Task	Idle time
I	A-B
II	D-C
III	F
IV	E
V	G-H

 

(d)	What is the efficiency of the line balanced as in (c)? (Round your answer to 1 decimal place. Omit the "%" sign in your response.)

Efficiency

%

 

(e)	Suppose that demand rose from 900 to 1,000 units per day. What would you do? (Round your answer to the nearest whole number.)

Reduce cycle time to seconds, which may require rebalancing the line.

 

(f)	Suppose that demand rose from 900 to 1,100 units per day. What would you do? (Round your answer to the nearest whole number.)

Reduce cycle time to seconds, which may require rebalancing the line.

Explanation:

(a):

C = production time per day/required output per day

 

C	=	Production Time Per day (in seconds)	=	8.75*(60*60)	=	35 seconds per unit
		Required Output per day		900

(b):

Ni	=	T	=	138	=	3.94 → 4 work stations
		C		35

(c):

Work station	Task	Task time	Idle time
I	A-B	18-12	5
II	D-C	14-10	11
III	F	28	7
IV	E	26	9
V	G-H	15-15	5

Total task time T = 138

(d):

Efficiency	=	T	=	138	=	0.789 or 78.9%
		NaC		5(35)

(e):

Reduce cycle time to 32. New production level is (8.75 hours/day)(3600seconds per hour)/(32 seconds per unit) = 984 units per day. Therefore, they are 1,000 – 984 = 16 units short. Work (16units)(32 seconds per unit) = 512 seconds overtime.

(f):

Reduce cycle time to 29. New production level is (8.75 hours/day)(3,600 seconds per hour)/(29 seconds per unit) = 1,086 units per day.