Scheduling Process-Focused Facilities PDF

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Scheduling Process-Focused Facilities...

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Scheduling Process-Focused Facilities Process-focused facilities (also known as intermittent or job-shop facilities), 1 as we see in Table 15.2, are high-variety, low-volume systems commonly found in manufacturing and service organizations. These are production systems in which products are made to order. Items made under this system usually differ considerably in terms of materials used, order of processing, processing requirements, time of processing, and setup requirements. Because of these differences, scheduling can be complex. To run a facility in a balanced and efficient manner, the manager needs a production planning and control system. This system should: • Schedule incoming orders without violating capacity constraints of individual work centers. • Check the availability of tools and materials before releasing an order to a department. • Establish due dates for each job and check progress against need dates and order lead times. • Check work in progress as jobs move through the shop. • Provide feedback on plant and production activities. • Provide work efficiency statistics and monitor operator times for payroll and labor distribution analyses. Whether the scheduling system is manual or automated, it must be accurate and relevant. This means it requires a production database with both planning and control files. Three types of planning files are: 1. An item master file, which contains information about each component the firm produces or purchases. 2. A routing file, which indicates each component’s flow through the shop. 3. A work center master file, which contains information about the work center, such as capacity and efficiency. Control files track the actual progress made against the plan for each work order. Loading Jobs Loading means the assignment of jobs to work or processing centers. Operations managers assign jobs to work centers so that costs, idle time, and completion times are kept to a minimum. Loading work centers takes two forms.2 One is oriented to capacity; the second is related to assigning specific jobs to work centers. First, we examine loading from the perspective of capacity via a technique known as input– output control. Then, we present two approaches used for loading: Gantt charts and the assignment method of linear programming.

INPUT–OUTPUT CONTROL Many firms have difficulty scheduling (i.e., achieving effective throughput) because they over-load the production processes. This often occurs because they do not know actual performance in the work centers. Effective scheduling depends on matching the schedule to performance. Lack of knowledge about capacity and performance causes reduced throughput. Input–output control is a technique that allows operations personnel to manage facility work flows. If the work is arriving faster than it is being processed, the facility is overloaded, and a backlog develops. Overloading causes crowding in the facility, leading to inefficiencies and quality problems. If the work is arriving at a slower rate than jobs are being performed, the facility is under-loaded, and the work center may run out of work. Under-loading the facility results in idle capacity and wasted resources. Example 1 shows the use of input–output controls....