Question

Consider the following tasks, times, and predecessors for an assembly of set top cable converter boxes:

TASK ELEMENT	TIME (MINUTES)	ELEMENT PREDECESSOR
A	3	—
B	3	A
C	2	B
D	2	B
E	1	C, D
F	1	A
G	3	F
H	3	G
I	1	E, H

Given a cycle time of six minutes, what is the efficiency of your layout? Use the longest task time as primary criterion with largest number of following tasks as secondary criterion.

Answer 1

The assignment of tasks in the stations as per the LPT rule is as follows:

Station	Remaining time	Eligibles	Was Fit	Assigned time	Remaining time	Idle time
I	6	A	A	3	3	0
	3	B, F	B	3	0
	0	C, D, F	-	-	0
II	6	C, D, F	C	2	4	0
	4	D, F	D	2	2
	2	E, F	F	1	1
	1	E, G	E	1	0
	0	G	-	-	0
III	6	G	G	3	3	0
	3	H	H	3	0
	0	I	-	-	0
IV	6	I	I	1	5	5

Efficiency = Sum of task times / (No. of stations * Cycle time)

= 19 / (4*6)

= 0.7917 or 79.17%