In recent times, a number of organizations are focusing on increasing business performance by improving scheduling like scheduling of delivery vehicles, scheduling of salesman visits to different towns, scheduling of operations on shop floor, scheduling of aircrafts, scheduling of activities for launching a spaceship etc. The concern is assigning a given set of machines and possibly other resources to a set of tasks in order to execute the tasks optimally subject to certain constraints, such as deadlines, availability of resources, priorities for some tasks over others or machine capabilities.
Scheduling is simply the allocation of resources over time to perform a set of tasks. Production being an integral part of a company catches a lot of attention and faces major scheduling/rescheduling issues.
There are two basic steps in production scheduling
Step I: Defining the problem: It includes understanding of the shop floor layout, machine capacities, routings, alternate resources, processing constraints, various shop floor events and the existing and desired ability to deal with these events (like change in resource, change in material availability, change in demand).
Above all the scheduling objective needs to be spelt out clearly. E.g.,
Scheduling objectives can be minimization of WIP, due date performance,
maximization of throughput, level loading etc.
To build a robust scheduling solution, there
are number of approaches/ algorithms like "disjunctive graph model",
"polynomial algorithms", "dynamic programming algorithms",
"polynomial approximation schemes", "branch and bound
methods", "decomposition approaches", "simulated
annealing", "heuristics models", "theory of constraints"
The right model framework varies from company to company based upon
shop floor complexities and scheduling objectives.
Largely, scheduling issues can be tackled best
if the users are involved in the schedule construction process
and they interact with the schedule to input their subjective preferences
like sequencing constraints, due date preferences etc., and explore
interactively the possible trade-offs between
different schedule criteria.
Major benefits of a good schedule are
2000-10 DecisionCraft Inc.