Case study analysis and findings

¶ … Hi-Ho Yo-Yo, Inc. scheduling will depend on certain rules. To determine which of these will work the best, rules such as First Come First Served (FCFS), Shortest Processing Time (SPT), Due Date (DD), and Critical Ratio (CR) will be considered. When drawing up a schedule, the priority is to finish all orders as quickly and efficiently as possible, thereby reducing the likelihood of tardiness and/or number of tardy orders. Effective scheduling is essential, as the reputation of the company and its relationship with customers are affected by scheduling and its ability to fill orders on time, especially during busy times.

The FIFS rule requires orders to be dispatched according tot heir arrival time. Orders that are received run until they are completed. The main disadvantage of this rule is that orders that take longer to complete may hold up those that do not take as long, hence affecting the efficiency of the process. In Hi-Ho's case, Order A came in before Order B, but its due date is later (11 July) and it will also take longer to complete (6 days). This will hold up the process for Order B, which will take only 2 days to complete and is due on July 8. This affects the efficiency of the process. The FCFS rule can therefore be considered as inadequate to apply to our requirements.

The Due Date paradigm requires work to be scheduled according to their due dates. For our requirements, the jobs would then be scheduled in this sequence: B (8 July) A (11 July) D (19 July) C (25 July) E (29 July). The main obstacle here is that this scheduling paradigm does not take into account production times. This could affect the ability of the plant to finish orders on time.

The Shortest Processing Time (SPT) rule does take into account processing times. Orders are scheduled according to their processing times, thereby maximizing the efficiency of operations and meeting due dates without difficulty. According to this rule, our jobs would be scheduled as follows: B (2 days) D (3 days) A (6 days) C (8 days) E (9 days). In practical terms, this means that, as soon as a machine is freed, the shortest job that is ready will begin processing. This minimizes the mean waiting time for jobs from arrival to the start of processing, it also minimizes the waiting time and mean lateness of each job. While this is very efficient, it does not take into account setup times or due dates, which could affect the efficiency of production.

Critical ratio is a paradigm that divides the time remaining until due date by the word time remaining on the order. This enables the manufacturer to prioritize those jobs that have the highest intensity in terms of time needed and time available to complete any given job. The highest critical ratio is therefore enjoyed by our Order A, with 6 days of production time and a due date of 11 July. This is followed by Order C, with 8 days of production time and due on 25 July, Order E, with 9 days of production time and due on 29 July, Order B, with 2 days of production time and due on 8 July, and finally order D, with 3 days of production time and due on 19 July.

When taking the above into account, one might conclude that the simplest processes should be discarded, as there are crucial factors that they do not take into consideration. The FCFS process, for example, does not take into account either production times or due dates. The DD paradigm in turn does not take into account the processing time for each order.