Assignment
I. Show how all the Run Time and Capacity numbers in the process flow diagram in Figure 3 (page 7 of the note) were calculated. There are 6 Run Time numbers and 6 Capacity numbers. These calculations are explained in the note. Below is a table showing all details.
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Processes
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Run Times
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Capacity Numbers
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Order Taking
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1 minute per item meaning 3 minutes an order
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1 item per minute X 60 = 60 items an order
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Pre-Treatment
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60 min/56.8 items per hour = 1.06 minutes an item
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90 items in 95 minutes:
90/95 X 60 = 56.8 items
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Dry Cleaning
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5 minutes switching tanks and 55 minutes of run time for 90 items. 60/60 = 1 batch
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90 items an hour but can be increased if items are the same color
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Pressing
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24 items an hour
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48 items an hour with 2 presses
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Packing
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0.5 minutes per item or 2 items per minute
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120 items per hour
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Customer Pick Up & Payment
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1 minute per item
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60 items an hour
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II. What is the daily capacity (in terms of number of customers served) of the dry-cleaning process as a whole? Assume each day is 12 hours long.
III. Suppose capacity at Pressing is doubled by adding 2 persons and 2 pressing machines. What is the new daily capacity (number of customers served) of the dry-cleaning process as a whole?
IV. Customers have been complaining that stains are not removed properly. So the laundry reduces the batch size in pre-treatment to 75 items. Pre-treatment still takes 90 minutes plus 5 minutes for solvent tank change. Now what is the hourly capacity of pre-treatment? How does this impact the overall capacity of the process?
V. How much does the hourly capacity of the dry-cleaning machine change if the batch size is increased to 120 items from 90 items?
VI. How much does the hourly capacity of the dry-cleaning machine change if tanks are switched only every 5 runs?
VII. Suppose 200 customers drop off laundry over a typical 12-hour day. What is the utilization of each of the different stages of the dry-cleaning process? Show in the form of a table. Will there be a problem? Do not consider the changes suggested in questions 3-6.
VIII. If the average number of clothes per customer increases from 3 to 4, which stages would be most impacted by this? Assume 180 customers per 12-hr day as stated in the case. Answer by calculating the utilization at each stage. Is the current system capable of dealing with this increase?