Question

1. [Layout Strategy-Line Balancing] The call center department of Jax-steel company needs to service 3,000 calls per 40-hour workweek. The process of servicing calls can be broken down into the six stations listed above. The precedence and time requirements for each element are as follows in the table below. The manager wants a new operational analyst to draw and label a precedence diagram for the service process. Finally, the manager needs to balance the line, calculate the efficiency of the line, and identify where and how much idle time exists. Precedence and Time Requirements of the Call Center Service Process Work Element Predecessor Performance/Processing A - Receive a Call B Route a Call C Tag a Call D-Start a FormG E- Fill in Box 9 in the Form F- Advise Caller Time (min) 0.1 0.3 0.5 0.2 0.6 0.4 C, D B. E (a) Draw a precedence diagram of this service operation (b) For a given demand of service calls per week, what is the cycle time for this operation? (c) What is the theoretical minimum number of workstations? (d) Assign the tasks to workstations to minimize slack time at each workstation ( to maximize the efficiency/utilization). *You may show your work in the network diagram in part (a) above. (e) What is the efficiency of this service operation process?

Answer 1

a)

The precedence diagram is shown below.

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b)

The demand = 3000

Total available time = 40*50 = 2400

Cycle time = available time / demand = 2400/3000 = 0.8 min

c)

The total task time = 2.1 minutes

Cycle time = 0.8 minutes

Theoretical number of workstation = 2.1/0.8 = 2.625

Rounding up, we need minimum 3 workstations

d)

Workstation line balancing table is shown below

Workstation	Task assigned	Task ready	Time left	Idle time
1	D, A, C,	(A), (B,C), (B, E),	0.6, 0.5, 0	0
2	E,	(B),	0.2	0.2
3	B, F,	(F), (-)	0.5, 0.1	0.1

e)

The total task time = 2.1 min

The total available time in 3 workstation = 2.4 minutes

The efficiency = total task time/total available time = 2.1/2.4 = 0.875 or 87.5%