I NEED HELP SOLVING A. B. AND number of workstations with labor Problem 6-21 Con
ID: 342908 • Letter: I
Question
I NEED HELP SOLVING A. B. AND number of workstations with labor
Problem 6-21 Consider the following tasks, times, and predecessors for an assembly of set-top cable converter boxes TASK ELEMENT (MINUTES) PREDECESSOR TIME ELE 1) C, D E, H Given a cycle time of six minutes, develop an assembly line layout. Use the longest task time rule and the largest number of following tasks as a secondary criterion. What is the efficiency of your layout, assuming the 6-minute cycle time? (Round your answer to the nearest whole percent.) EfficiencyExplanation / Answer
A.
Available hours = 7.5 hours per day
Demand = 324 units per day
Cycle time = CT = Available time/ Demand = TA/D = (7.5 x 60 x 60)/324 = 83.33 seconds per unit
Cycle time = 83.3 seconds per unit
B.
Total Task (labor) Time = Ti = 542 + 280 = 822 seconds
Minimum number of assembly position required = Total work time/CT = Ti/CT = 822/83.3 = 9.86
Minimum number of assembly position required = 10
Minimum number of workers/workstations required = Total labor time/CT = Ti/CT = 542/83.3 = 6.5
Minimum number of work station required = 7 work stations
Assembly position
Tasks
Workstation #
Labor Time
Cycle time remaining
1
1
1
80
3.33
2
2 and 3
2
53 + 23 = 76
7.3
3
4, 5, 9
3
31+23+22 = 76
7.3
4
6,7
4
44+30 = 74
9.3
5
8, 10
5
42 + 23 = 65
18.3
6
11, 12, 13, 14
6
47 + 8 + 6 + 10 = 71
0.3
15 (12 sec)
(No labor req)
7
15 (83.3 sec)
(No labor req)
0
8
15 (83.3 sec)
(No labor req)
0
9
15 (83.3 sec)
(No labor req)
0
10
15 (18.1 sec)
(No labor req)
15.2
16
7
50
11
17
8
50
33.3
12
empty
Actual number of assembly position required = 11
Efficiency (total work content is considered) = (Total time)/(number of assembly positions x Cycle time) x 100
Efficiency = (542 + 280)/(11 x 83.3) x 100 = 89.76%
Efficiency (total task content is considered) = 89.76%
Number of workstations with labor = 8 workstations
Assembly position
Tasks
Workstation #
Labor Time
Cycle time remaining
1
1
1
80
3.33
2
2 and 3
2
53 + 23 = 76
7.3
3
4, 5, 9
3
31+23+22 = 76
7.3
4
6,7
4
44+30 = 74
9.3
5
8, 10
5
42 + 23 = 65
18.3
6
11, 12, 13, 14
6
47 + 8 + 6 + 10 = 71
0.3
15 (12 sec)
(No labor req)
7
15 (83.3 sec)
(No labor req)
0
8
15 (83.3 sec)
(No labor req)
0
9
15 (83.3 sec)
(No labor req)
0
10
15 (18.1 sec)
(No labor req)
15.2
16
7
50
11
17
8
50
33.3
12
empty
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