Question

Q4   (a)   A manufacturer has the following jobs waiting on a single work centre. The firm has not decided which dispatching rule to apply in order to prioritize the jobs and fix them into the schedule. Processing time and due date for each job are in the Table 4 below. Recommend the best job sequence to the manufacturer using THREE (3) dispatching rules scenario analysis.

Table 4: Jobs Information

Jobs Information	Processing Time (days)	Due Date (days)
Job 1	3.25	8
Job 2	4.75	7
Job 3	4.5	9
Job 4	5	8
Job 5	4.5	7
Job 6	3.75	10
Job 7	4.25	9
Job 8	4	7

2. Nuqman established TT Flash Sdn Bhd, to manufacture Automatic Hand-Cleaner Dispenser Station to help curb the spread of Covid-19 in the country. The company received 5 orders with different design specification (Design F, G, H, I & J) that must be completed not more than 29 days. With the TT Flash Sdn Bhd manufacturing capability, the company estimated 40 days to deliver all the stations. To overcome this issue, Nuqman have call others company to build the Automatic Hand-Cleaner Dispenser Station and ask each company their estimation time to manufacture each design. The estimated time information of each design shown in Table 5.

1. Suggest to the company with justification the best alternative available for this order.

Table 5: Hand-Cleaner Dispenser Station Manufacturing Time Information

Design (days)
Company	F	G	H	I	J
TT Flash	9	5	12	6	8
P00	7	4	7	7	10
Q12	8	7	5	6	11
R34	6	7	11	10	9
S56	8	6	10	5	7

2. Ranjit, the industrial engineer in the company have recommend to Nuqman for implementing concurrent process for this orders with establishing two workstation to manufacture the Automatic Hand-Cleaner Dispenser Station, namely fabrication and assembly as shown in Table 6.

Evaluate the above proposal by Ranjit whether the company able to meet the order demand not more than 29 days.

Table 6: Station Processing Time Information for each workstation

Design	Fabrication (days)	Assembly (days)
F	5	4
G	2	3
H	6	6
I	4	2
J	5	3

Answer 1

Scheduling as per three dispatching rules is following:

Of the three rules, SPT gives the best results (lowest values) in terms of average flow time, average tardiness and average number of jobs in system

Therefore, jobs should be scheduled as per SPT rule as shown below:

Sequence	Job
1	Job 1
2	Job 6
3	Job 8
4	Job 7
5	Job 3
6	Job 5
7	Job 2
8	Job 4