Operating schedules are short term plans even day to day plans designed to implement the master schedule plans. Once a business plan is in place then a master schedule is made showing how many of each product must be produced according to the customer orders and demand forecast.
Short term scheduling covers a span of time ranging from a few months to a week. It deals with operations scheduling, which is a short term plan developed to implement the overall operations schedule. Operations scheduling deals with work center loading and job sequencing. In scheduling terms, a work center is defined as a location in a company or organization where productive resources are organized and work is completed.
Conversion system can be broadly classified as either continuous or intermittent depending on the conversion process and the product or service.
A continuous or assembly type system is one in which a large number or infinite number of units of a homogenous product is produced.
An intermittent, on the hand, produces a variety of products one at a time (in which case they are custom made) or in batches to customer order. Many conversion facilities are neither strictly intermittent nor continuous but a combination of both.
Implication in a manufacturing context: In the manufacturing context, intermittent systems are traditionally referred as job work or shops. Therefore a number of questions arise such as
- Which work centers will do which job?
- When should an operation / job be started? When should it end?
- On which shipments should be done, and by whom?
In manufacturing the sequencing in which waiting jobs are processed is critical to the efficiency and effectiveness of the intermittent systems. Sequencing affects how many jobs are completed on time versus late, costs incurred for set up and changeover, delivery lead times, inventory costs, and the degree of congestion in the facility scheduling of the intermittent systems poses a challenge for operations manager.
