Production scheduling

This problem is known in mechanical engineering as Job Shop Scheduling problem (JSSP), manufacturing scheduling. Optimization issues that involve allocating resources to perform a set of tasks at certain times are called planning problems. Comprehensive planning problems often arise in the machinery industries as well as in the companies providing air and packaging services. The goal of such problems is usually to find a plan that minimizes the total amount of time (or cost) required to complete all tasks. Of course, this method can be used also in other areas such as in the construction of larger complexes, where it is necessary to re-accord the various subtasks.

The orders are constantly coming into the production process. Technological processes describe method of realizing these orders, which indicate the sequence of performing operations and the way (network connections, jobs, working hours, time of execution etc.). This data gives an opportunity to scheduling manufacturing process at the machine fleet. When it is scheduling production, there is necessity to start individual production tasks in a way that there are no congestions. Congestion means that individual tasks cannot be accomplished on the workplace at the right time, while other workplaces are suffering due to absence of tasks (they do not have any tasks). How to avoid it and how to determine the timing is known as Job Shop problem. Different heuristic algorithms execute various optimization criteria during solution. It is possible to determine more optimization criteria such as maximum utilization of the machine fleet, maximum profit, respect the commitment deadlines, etc.

A conclusion is usually a specific production process plan shown in the following figure (Gantt chart).

There is a list of the different machines or working places on the right and on the left there are scheduled tasks which are displayed as the time-zones, for 3 jobs. Images show the optimization process. *

links:
Reinhard Burgy: Complex Job Shop Scheduling: A General Model and Method
Adonyi Róbert: Szakaszos folyamatok ütemezése
Christian Mattfeld: Evolutionary search and the Job Shop
The Job Shop Problem Solution with OR-Tools
HeuristicLab.com
Mathematical Problems in Engineering