Scheduling involves developing and assigning specific dates for the start and completion of the necessary tasks or operation in a production shop floor. The output plans indicated in master production schedules must be translated into detailed operational schedules to be implemented on the shop floor on a day to day basis. The operations scheduling and control process includes activities such as priority sequencing, detailed scheduling, loading, expediting and input/output control. The various terms used in operations planning and scheduling are described briefly in the following paragraphs.
Loading sometimes known as shop loading or machine loading, is the assignment of jobs to various work centers or machines for future processing, giving due consideration to the sequence of operations as per the route sheet and the priority sequencing and machine/work center utilization. Loading establishes the amount of load (labor hours or machine hours) each work center or machine must carry during the future planning period (weekly or monthly). This will result in load schedules which indicate comparison of labor and machine hours needed to produce the master production schedules with the labor and machine hours actually available in each planning period (week or month) in the short-term planning horizon.
Sequencing is the process of determining the sequence of processing of all jobs at each work center or machine. It establishes the priorities for processing the jobs which are waiting in the queue at each work center or machine. The priority sequencing is done as per a priority sequencing rule.
Detailed scheduling is the process of determining the start and finish times (dates) at each work center or machine for all jobs. Detailed scheduling is possible only after loading and sequencing. By knowing the duration of time each job takes to complete, the operation at each work center/machine and also by knowing the due dates, the detailed schedule indicating the start and finish dates be established.
Expediting is the special effort or action needed to keep the job moving through the production facility on time as per the detailed schedule. Disruptions in production due to machine/equipment break downs, non-availability of materials when needed, last-minute priority changes due to special jobs having over-riding priorities, necessitate the expediting action for some important jobs. This requires operations managers to deviate from the existing plans and schedules.
Input-Output control plans and schedules call for certain levels of capacity at a work center or machine, but actual utilization may differ from what was planned. Input-output control is a key activity that provides detailed information about the actual utilization of a work center or machineâ€™s capacity versus the planned capacity utilization. It gives a picture if flows of jobs between work centers. Problems such as insufficient capacity at work stations and problems at up-streams work stations can be identified through the input-output control.