Question

2. Show all the steps for the question to be worth any marks.

The following table presentss the tasks, durations, and immediate predecessors necessary to produce a particular Rroduct The required daily output is 320 units, and the working day is 8.0 hours on an assembly line. Immediate Predecessor Duration (in minutes) Activity A 0.9 B 0.7 C 0.8 Г E 0.4 В, с А, D E 0.5 0.4 G E 0.6 Н F, G 0.5 T 1.1 a. Draw the precedence diagram for this problem b. Determine the required cycle time. c. Determine the theoretical minimum number of workstations d. The positional weight of a task is the sum of the task time plus the task times of all following tasks. Calculate the positional weights of the tasks e. Assign tasks to workstations, using "highest positional weight" as the primary rule and "longest operating time" as the secondary rule. Show your calculations and task assignments in a chart f. Calculate the efficiency of the solution

Answer 1

a.

04 O-9 0.4 1-4 B 0.5 08

b)

Required cycle time = Available time/desired output = (8*60)/320 = 1.5 minutes

c)

Theoretical minimum number of workstations = Sum of task times/cycle time = 5.9/1.5 = 3.933333333 = 4 (Rounded to next whole number)

d)

Activity	Positional weight
A	2.9
B	4.2
C	3.5
D	3.4
E	2.7
F	2
G	2.2
H	1.6
I	1.1

e)

Workstation	Feasible task	Assigned task	task time	Idle time remaining
I	A,B,C	B	0.7	0.8
	A,C,D	C	0.8	0
II	A,D,E	D	0.4	1.1
	A,E	A	0.9	0.2
III	E,F	E	0.5	1
	F,G	G	0.6	0.4
	F	F	0.4	0
IV	H	H	0.5	1
V	I	I	1.1	0.4

f)

Efficiency = Sum of task times/(no of workstations*cycle time) = (5.9/(5*1.5))*100 = 78.66666667%