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CHAPTER 4: FLOW TIME ANALYSIS
4.3 Solutions to the Problem Set

Problem 4.1
[a] Draw a process flow diagram.

[b]. The theoretical flow time is 36 minutes:

There are three paths through the system:

A: Take Order – Food – Deliver – Bill → 4 + 18 + 12 + 2 = 36 mins
B: Take Order – Wine – Deliver – Bill → 4 + 4.8 + 12 + 2 = 22.8 mins
C: Take Order – Cart – Deliver – Bill → 4 + 10 + 12 + 2 = 28 mins

Path A is critical so the TFT is 36 minutes

[c]. The flow time efficiency is 36/60 = 60%

Problem 4.2

[a] The flow chart of the process is as shown in Figure TM-4.1.

Figure TM-4.1. Flow chart of the Kristen Cookies Process flow

Flow unit = 1 order of 1 dozen the theoretical flow time is 26 minutes. This is …show more content…

3. With one faster convection oven, we can repeat the procedure as for a single oven (using the Gantt chart). The first dozen starts baking in the convection oven at the 9th minute and finishes baking at the 15th minute. Meanwhile the second dozen is ready to go into the oven. The RM sets the timer in 1 minute and the baking process for the second dozen starts at the 16th minute and ends at the 22nd minute. Meanwhile, there is just enough time for the first dozen to cool and be packed. At the end of 22nd minute, the RM unloads the second dozen, lets it cool for 5 minutes and packs them taking 2 more minutes. The order is ready by 29th minute at which time it is delivered and payment is accepted, giving a total theoretical flow time of 30 minutes.
Problem 4.3

[a] From Table 4.9 of the Problem set, we compute the work content of various activities as shown in Table TM-4.2. As in Example 4.3, the two paths are:
Path 1 (roof): Start → 1→ 3 → 5 → 7 → 8 → End
Path 2 (base): Start → 1→ 2 → 4 → 6 → 7 → 8 → End The theoretical flow time of each path is determined by adding the work contents of the activities along that path. Thus the theoretical flow time of path 1 is 100 minutes and that of path 2 is 127 minutes. Path 2 is then the critical path and the theoretical flow time for the Deluxe model is 127 minutes.

[b] Table 4.2 of the chapter gives the work content of the standard garage. Taking a weighted combination