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Question 1 : What should be the starting time of the jobs on the constraints?
Should there be start and stop times per
job in the schedule? As times are influenced by a lot of factors
(statistical fluctuations, Murphy, non-availability of resources), they
will never be as forecast. Furthermore, what happens if a worker sees he
will finish too early? |
We tell the foreman: 'Do it as fast as possible'. That is the best he can do.
Realize, that only time saved on the constraint gives him the possibility to produce more ... and time lost on the
constraint can not be recovered.
Question 2 :
In which sequence should we plan the jobs?
'In the sequence we have promised our customers by means of a due date (remember: we produce salable products!)'. We tell the
foreman: 'Do it in this sequence'. So our schedule should be:
| Order |
Quantity |
Due Week |
Due Day |
| 6 |
50 |
10 |
3 |
| 1 |
75 |
10 |
3 |
| 4 |
40 |
10 |
4 |
| 5 |
80 |
10 |
5 |
| 3 |
30 |
11 |
1 |
| 2 |
60 |
11 |
3 |
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Table 3.3.: Order Load Factory 2 |
This schedule is the priority schedule for constraint resource D.
We tell the foreman: 'Do it in this sequence and as fast as possible'. That is the best he can do.
N.B. Job 1 and job 6 have the same order due date.
Is there a particular reason for the sequence of job number 1 and 6?
Yes, I have put 6 in front of 1 because 6 is a shorter job. The chance that Murphy or anything else stops your
production is always there. If your longest job is your last one and you have a problem with your due dates, then
you hurt the minimum number of customers.
By the way, is this also true, if job 1 is for your best customer?
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