Basic Tools for Process Design
Discussion Questions and Exercises
1 Develop a general process chart for the requisition process in Exercise 1.1.
2 Develop a general process chart for the receiving and delivering process in Exercise 1.2.
3 Develop a process activity chart for the IBM Credit example in Section 1.1.2.
4 Develop a flowchart for the claims-handling process in Section 1.2.2.
5 A department within an insurance company is considering the layout for a rede-signed process. A computer simulation was built to estimate the traffic from each pair of offices. The load matrix in Table 4.14 summarizes the daily traffic.
a. If other factors are equal, which two offices should be located closest to one another?
b. Figure 4.21 shows one possible layout for the department. What is the total LD score for this plan using rectilinear distance? (Hint: The rectilinear distance between offices A and B is 3.)
c. Switching which two departments will most improve the total LD score?
6 A firm with four departments has the load matrix shown in Table 4.15 and the current layout shown in Figure 4.22.
a. What is the LD score for the current layout? (Assume rectilinear distance.)
b. Find a better layout. What is its total LD score?
TABLE 4.14
Load Matrix for Exercise 4.5
| From\To B |
C |
E |
F |
| A |
10 |
75 |
140 |
| B |
95 |
|
|
| C |
|
130 |
130 |
| D |
|
10 |
|
| E |
|
|
95 |
FIGURE 4.21
Current layout for Exercise 4.5.
TABLE 4.15
Load Matrix for Exercise 4.6
| From\To |
B |
C |
D |
| A |
12 |
10 |
8 |
| B |
|
20 |
6 |
7 A scientific journal uses the following process to handle submissions for publication:
• The authors send the manuscript to the Journal Editorial Office (JEO).
• The JEO sends a letter to the authors to acknowledge receipt of the manuscript. The JEO also sends a copy of the manuscript to the editor-in-chief (EIC).
• The EIC selects an associate editor (AE) to be responsible for handling the manu¬script and notifies the JEO.
• The JEO sends a copy of the manuscript to the AE.
• After reading the manuscript, the AE selects two referees who have agreed to review the paper. The AE then notifies the JEO.
• The JEO sends copies of the manuscript to the referees.
• The referees review the manuscript and send their reports to the JEO.
• The JEO forwards the referee reports to the appropriate AE.
• After reading the referee reviews, the AE decides whether the manuscript should be rejected, accepted, or revised. The decision is communicated to the JEO.
• If the manuscript is rejected, the JEO sends a letter to the authors thanking them for the submission (and wishing them good luck getting the manuscript published somewhere else!).
• If the manuscript is accepted, the JEO forwards the manuscript to production. The JEO also notifies the authors and the EIC.
• If the manuscript needs revisions, the JEO forwards the referee reviews to the authors.
• The authors revise the manuscript following the recommendations outlined in the referee reports. The authors then resubmit the manuscript to the JEO.
• The JEO sends a resubmission directly to the responsible AE.
• After reading a resubmitted manuscript, the AE decides whether the revised ver-
sion can now be accepted or needs to be sent to the referees for further reviewing.
a. Construct a service system map for this process.
b. Identify opportunities for redesigning the process.
8 Calculate the efficiency of the line-balancing solution depicted in Figure 4.17.
9 Modify Ragsdale and Brown spreadsheet model* to solve the line-balancing problem described in Example 4.1.
TABLE 4.16
Data for Exercise 4.10
| Activity |
Time (Min) |
Immediate Predecessor |
| A |
70 |
|
| B |
15 |
A |
| C |
8 |
|
| D |
32 |
|
| E |
47 |
C, D, G |
| F |
25 |
B, E |
| G |
61 |
|
| H |
52 |
|
| I |
29 |
G, H |
| J |
42 |
I |
| K |
50 |
F, J |
10 Sola Communications has redesigned one of its core business processes. Processing times are not expected to vary significantly, so management wants to use the line-balancing approach to assign activities to workstations. The process has 11 activities, and the market demand is to process 4 jobs per 400 min working day. Table 4.16 shows the standard time and immediate predecessors for each activity in the process.
a. Construct a precedence diagram.
b. Calculate the cycle time corresponding to a market demand of 4 jobs per day.
c. What is the theoretical minimum number of workstations?
d. Use the longest activity time rule as the primary rule to balance the line.
e. What is the efficiency of the line? How does it compare with the theoretical maxi¬mum efficiency?
f. Is it possible to improve the line's efficiency? Can you find a way of improving it?
11 A process consists of eight activities. The activity times and precedence relationships are given in Table 4.17. The process must be capable of satisfying a market demand of 50 jobs/day in a 400 min working day. Use the longest activity time rule to design a process line. Does the line achieve maximum efficiency?
TABLE 4.17
Data for Exercise 4.11
| Activity |
Time (Min) |
Immediate Predecessor |
| A |
5 |
|
| B |
4 |
|
| C |
2 |
A |
| D |
3 |
A and B |
| E |
2 |
B |
| F |
6 |
D and E |
| G |
3 |
C and F |
| H |
2 |
F |
TABLE 4.18
Data for Exercise 4.12
| Activity |
Time (Min) |
Immediate Predecessor |
| A |
3 |
|
| B |
2 |
A |
| C |
4 |
B |
| D |
7 |
|
| E |
4 |
D and G |
| F |
5 |
|
| G |
6 |
F |
| H |
9 |
C and E |
| I |
5 |
H |
12 A process manager wants to assign activities to workstations as efficiently as pos-sible and achieve an hourly output rate of four jobs. The department uses a working time of 56 min/h. Assign the activities shown in Table 4.18 (times are in minutes) to workstations using the "most followers" rule. Does the line of workstations achieve maximum efficiency?
13 A business process has a market demand of 35 jobs per day. A working day consists of 490 min, and the process activity times do not exhibit significant amounts of varia¬tion. A process management team would like to apply the line-balancing technique to assign activities to workstations. The activity times and the immediate predeces¬sors of each activity are given in Table 4.19.
a. Use the longest activity rule as the primary rule to assign activities to stations.
b. Compare the efficiency of the line with the theoretical maximum efficiency. Is it possible to improve the line efficiency?
14 Longform Credit receives an average of 1200 credit applications/day. Longform's advertising touts its efficiency in responding to all applications within hours. Daily application-processing activities, average times, and required preceding activities (activities that must be completed before the next activity) are listed in Table 4.20.
TABLE 4.19
Data for Exercise 4.13
| Activity |
Time (Min) |
Immediate Predecessor |
| A |
3 |
- |
| B |
6 |
- |
| C |
7 |
A |
| D |
5 |
A, B |
| E |
2 |
B |
| F |
4 |
C |
| G |
5 |
F |
| H |
7 |
D, E |
| I |
1 |
H |
| J |
6 |
E |
| K |
4 |
G, I, J |
TABLE 4.20
Data for Exercise 4.14
|
Activity
|
Description
|
Time (Min)
|
Immediate
Predecessor
|
|
A
|
Open and stack applications
|
0.20
|
-
|
|
B
|
Process enclosed letter; make note of and handle any special requirements
|
0.37
|
A
|
|
C
|
Check off form 1 for page 1 of application
|
0.21
|
A
|
|
D
|
Check off form 2 for page 2 of application; file original copy of application
|
0.18
|
A
|
|
E
|
Calculate credit limit from standardized tables according to forms 1 and 2
|
0.19
|
C and D
|
|
F
|
Supervisor checks quotation in light of special processing of letter and notes type of form letter, address, and credit limit to return to applicant
|
0.39
|
B and U
|
|
|
Secretary types details on form letter and mails
|
0.36
|
E, F
|
Assuming an 8 h day, find the best assignment of activities to workstations using the longest activity time rule. Calculate the efficiency of your design. Has your design achieved maximum efficiency?
15 Suppose the jobs in Table 4.21 must be processed at a single facility. (All times are given in minutes.) Assume that processing starts after the last job arrives, that is, at time 20. Compare the performance of each of the following scheduling rules according to the average weighted tardiness, maximum tardiness, and number of tardy jobs:
a. FIFO
b. EDD
c. SPT
16 Consider the jobs in Table 4.22. Use Moore's algorithm to find the sequence that mini-
mizes the number of tardy jobs. Assume that processing can start at time zero.
17 Time commitments have been made to process seven jobs on a given day, starting at 9:00 AM. The manager of the process would like to find a processing sequence that minimizes the number of tardy jobs. The processing times and due dates are given in Table 4.23.
TABLE 4.21
Data for Exercise 4.15
| Job |
Arrival Time (Min) |
Estimated Processing Time (Min) |
Due Date |
Importance (Weight) |
| A |
3 |
23 |
76 |
20 |
| B |
6 |
12 |
54 |
18 |
| C |
8 |
34 |
87 |
27 |
| D |
12 |
16 |
98 |
12 |
| E |
15 |
8 |
37 |
10 |
| F |
20 |
19 |
62 |
23 |
TABLE 4.22
Data for Exercise 4.16
| Job |
A |
B |
C |
D |
E |
F |
| Due date |
15 |
6 |
9 |
23 |
20 |
30 |
| Processing Time |
10 |
3 |
4 |
8 |
10 |
6 |
TABLE 4.23
Data for Exercise 4.17
| Job |
A |
B |
C |
D |
E |
F |
G |
| Due time |
11:00 |
15:00 |
10:05 |
12:45 |
14:00 |
12:40 |
13:00 |
| Processing Time |
0:30 |
1:15 |
1:00 |
0:20 |
0:45 |
2:00 |
1:10 |
TABLE 4.23
Data for Exercise 4.17
| Location |
Repair Time |
Due Time |
| Walnut |
1:15 |
2:00 PM |
| Valmont |
2:30 |
Noon |
| Topaz |
1:45 |
10:00 AM |
| Wright |
0:30 |
11:00 AM |
| Baseline |
2:00 |
3:00 PM |
18 A telecommunications company needs to schedule five repair jobs on a particular day in five locations. The repair times (including processing, transportation, and breaks) for these jobs have been estimated as shown in Table 4.24. Also, the customer service representatives have made due date commitments as shown in the table. If a due date is missed, the repair needs to be rescheduled, so the company would like to minimize the number of missed due dates. Find the optimal sequence, assuming that the first repair starts at 8:00 AM.
Textbook - BUSINESS PROCESS MODELING, SIMULATION AND DESIGN - SECOND EDITION by Manuel Laguna and Johan Marklund