Hi-Ho Yo-Yo, Inc. 1

Hi-Ho Yo-Yo, Inc.

BUS 644

Hi-Ho Yo-Yo, Inc. 2

First we must incorporate priority rules. Priority rules are regulations which determine in which succession the orders in front of a production line should be worked (Stevenson 2011, p. 712). In deciding what priority rules to acclimate, an organization such as Hi-Ho Yo-Yo, Inc. should achieve the following objectives:
1. Meet due dates of the customers if the product goes directly to them or the downstream operations if the product is but an input of another.
2. Minimize the time the order spends within the process including wait time.
3. Minimize work-in-process inventory which inevitable ties resources which can otherwise be used in more productive activities.
4. Minimize idle time of both machine and human resources.
Given these objectives, Hi-Ho Yo-Yo, Inc. can choose from different priority rules and some of the most popular are as follows: (Retrieved from table 16.2, Stevenson 2011, p. 712).
First Come First Serve If Hi-Ho Yo-Yo, Inc. chooses this method to decide how the 5 orders are lined up, this will mean that the first order received will be processed first. The following table shows how this choice measures according to different measures of effectiveness:
Job Date Order Received Set-Up Time (days) Production Time (days) Total Processing Time Flow Time Due Date Delays
A 6/4 0.25 6 6.25 6.25 11 -
B 6/7 0.50 2 2.50 8.75 8 0.75
C 6/12 0.25 8 8.25 17.00 25 -
D 6/14 0.50 3 3.50 20.50 19 1.50
E 6/15 0.50 9 9.50 30.00 26 4.00 Total 30.00 82.50 6.25
Hi-Ho Yo-Yo, Inc. 3

Average completion time 16.50 days
Utilization 36.36%
Average no. of jobs 2.75
Average job delays 1.25 days

Shortest Processing Time This rule processes the order with the shortest total processing time first.
Job Date Order Received Set-Up Time (days) Production Time (days) Total Processing Time Flow Time Due Date Delays
B 6/7 0.50 2 2.50 2.50 8 -
D 6/14 0.50 3 3.50 6.00 19 -
A 6/4 0.25 6 6.25 12.25 11 1.25
C 6/12 0.25 8 8.25 20.50 25 -
E 6/15 0.50 9 9.50 30.00 26 4.00 Total 30.00 71.25 5.25

Average completion time 14.25 days
Utilization 42.11%
Average no. of jobs 2.375
Average job delays 1.05 days

Hi-Ho Yo-Yo, Inc. 4

Due Date This priority rule processes the order with the earliest due dates first.
Job Date Order Received Set-Up Time (days) Production Time (days) Total Processing Time Flow Time Due Date Delays
B 6/7 0.50 2 2.50 2.50 8 -
A 6/4 0.25 6 6.25 8.75 11 -
D 6/14 0.50 3 3.50 12.25 19 -
C 6/12 0.25 8 8.25 20.50 25 -
E 6/15 0.50 9 9.50 30.00 26 4.00

Total 30.00 74.00 4.00

Average completion time 14.80 days
Utilization 40.54%
Average no. of jobs 2.466667
Average job delays 0.80 days

Critical Ratio Critical ratio is measured by dividing the time remaining until due date by the work time remaining. The critical ratio is computed assuming that there are 23 working days in July as stated in the case.
Job Due Date Today's Date Work Days Remaining Critical Ratio Priority Order Comment
A 11-Jul 1-Jul 10 0.43 2 The job is falling behind schedule
B 8-Jul 1-Jul 7 0.30 1 The job is falling behind schedule
C 25-Jul 1-Jul 24 1.04 4 The job is ahead of schedule and has some slack
D 19-Jul 1-Jul 18 0.78 3 The job is falling behind schedule
E 26-Jul 1-Jul 25 1.09 5 The job is ahead of schedule and has some slack
Hi-Ho Yo-Yo, Inc. 5

The results of the four priority rules above are presented below:
Priority Rule Average completion time (days) Utilization (%) Average no. of jobs Average job delays (days)
FCFS 16.50 36.36% 2.75 1.25
SPT 14.25 42.11% 2.375 1.05
DD 14.80 40.54% 2.466667 0.80 (Stevenson 2011, p. 712, Tbl 16.2). Based on the above, SPT is the most effective rule based on the shortest average completion time in days, utilization rate, and average number of jobs while DD is the most effective in terms of the least average job delays in days. Shortest processing time is generally the best technique in minimizing job flows and minimizing the average number of jobs in the production system. However, if Jack Baker concentrates on meeting due dates, then the due date priority rule should be the one followed as this method results to the least number of job delays in days.

Hi-Ho Yo-Yo, Inc. 6

References
Stevenson, W.J. (2011). Operations management (11th ed). New York, NY