Production Scheduling Nahmias, Chapter 8 ( D t lj l i ) (sv ...

The Good News on Scheduling (I)
�We can control the problem by controlling the environment
– Do not accept all traditional constraints as fixed
– Design the environment to facilitate easier scheduling
– EExactly tl what h tth the Japanese J did when h they th made d a hard h dscheduling h d li
problem much easier by drastically reducing set up times
Strategies that simplifies scheduling…
• Due Dates: We can set the due dates (within reason).
• Job Splitting: We can get smaller jobs by splitting large ones.
– Single machine SPT results imply small jobs “clear out” more quickly
than larger jobs.
– Mechanics of Johnson’s algorithm implies we should start with a small
job and end with a small job.
– Small jobs make for small “move” batches and can be combined to
form larger “process” batches.
The Good News on Scheduling (II)
Strategies that simplifies scheduling… (cont.)
• Feasible Schedules: We do not need to find an optimal
schedule, hdl only l a good dffeasible iblone.
• Focus on Bottleneck: We can often concentrate on
scheduling the bottleneck process, which simplifies
problem closer to single machine case.
– Assumes relatively stable bottlenecks
• Capacity: Capacity can be adjusted dynamically
(overtime, floating workers, use of vendors, etc.) to adapt
facility (somewhat) to schedule.
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