Question

4. A company is designing an assembly line for a new line of lamps. It has identified 9 tasks and arranged them as in the following figure. The number in each circle represents the time to complete the task in minutes. Demand for the product is expected to be 20,000 units a year. The new as- sembly line is scheduled to work 8 hour days, 5 day weeks and 50 weeks per year. E 4 F 1 A 4 H 4 3 3 D 3 G 2

Answer 1

(d)

Required production per year = 30,000 units

Available time per year = 50*5*8*60 minutes = 120,000 minutes

So, the required cycle time = 120,000 / 30,000 = 4 minutes

Station	Remaining time	Eligibles	Was fit	Assigned time	Time remains	Idle time
I	4	A	A	4	0
	0	B	-	-	0	0
II	4	B	B	3	1
	1	C, D	-	-	1	1
III	4	C, D	C	4	0
	0	D, E, F	-	-	0	0
IV	4	D, E, F	E	4	0
	0	D, F	-	-	0	0
V	4	D, F	D	3	1
	3	F, G	F	1	0
	0	G	-	-	0	0
VI	4	G	G	2	2
	2	H	-	-	2	2
VII	4	H	H	4	0
	0	I	-	-	0	0
VIII	4	I	I	3	1
	1	-	-	-	1	1

So,

Eight stations as above will be formed with eight workers working on each station.

(e)

Required production per year per line = 15,000 units

Available time per year = 50*5*8*60 minutes = 120,000 minutes

So, the required cycle time = 120,000 / 15,000 = 8 minutes

Station	Remaining time	Eligibles	Was fit	Assigned time	Time remains	Idle time
I	8	A	A	4	4
	4	B	B	3	1
	1	C, D	-	-	1	1
II	8	C, D	C	4	4
	4	D, E, F	E	4	0
	0	D, F	-	-	0	0
III	8	D, F	D	3	5
	5	F, G	G	2	3
	3	F	F	1	2
	2	H	-	-	2	2
IV	8	H	H	4	4
	4	I	I	3	1
	1	-	-	-	1	1

So,

Both the single lines will contain four stations with one worker working in each station. So, the number of workers required will still be eight.

(f)

Total idle time per cycle in the single line = 0+1+0+0+0+2+0+1 = 4 minutes, Balance delay = 4 / (8*4) = 12.5%

Total idle time per cycle in the double line = 1+0+2+1 = 4 minutes, Balance delay = 4 / (4*8) = 12.5%

So, in both the cases, the resources seem to be equally loaded. Using overtime in each of these two cases should be indifferent.