Chapter 16 scheduling PDF

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Professor Christopher Brock, contains bulleted list of important topics covered in chapter 16 of the textbook....

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BUSI 411 Chapter 16: Scheduling  Scheduling – establishing the timing of the use of specific resources of that organization, relates to the use of equipment, facilities, and human activities  In the decision-making hierarchy, scheduling decisions are the final step in the transformation process before actual output occurs  Effective scheduling can yield cost savings, increases in productivity, and other benefits  Generally, the objectives of scheduling are to achieve trade-offs among conflicting goals, which include efficient utilization of staff, equipment, and facilities, and minimization of customer waiting time, inventories, and process times.  Scheduling encompasses allocating workloads to specific work centers and determining the sequence in which operations are to be performed  High-volume systems goal of scheduling is to obtain a smooth rate of flow of goods or customers through the system in order to get a high utilization of labor and equipment  High volume systems usually require automated or specialized equipment, several factors determine the success of such a system::: 1) process and product design. 2) preventive maintenance. 3) rapid repair when breakdowns occur. 4) optimal product mixes. 5) minimization of quality problems. 6) reliability and timing of supplies.  Intermediate volume systems typically produce standard outputs; it is more economical to process these items intermittently; run sizes are relatively large.  3 basic issues in intermediate volume systems are the run size of jobs, the timing of jobs, and the sequence in which jobs should be processed  Job shops include ERs, repair shops, etc. products are made to order and services are performed according to need.  Job shop processing gives rise to two important issues for schedulers; how to distribute the workload among work centers and what job processing sequence to use.  Loading – assignment of jobs to processing (work) centers  Gantt charts – used for a variety of purposes related to loading and scheduling; purpose is to organize and visually display the actual or intended use of resources in a time framework; many different types of these charts, two of the most common ones are the load chart and the schedule chart  Two approaches are used to load work centers::: 1) infinite loading (assigns jobs to work centers without regard to the capacity of the work center). 2) finite loading (projects actual job starting and stopping times at each work center).  Two general approaches to scheduling::: 1) forward scheduling (scheduling ahead from a point in time). 2) backward scheduling (scheduling backward from a jobs due date).  Input/output (I/O) control – monitoring the work flow and queue lengths at work centers; purpose of I/O control is to manage work flow so that queues and waiting times are kept under control

 Hungarian method = helps to ID lowest cost solution, each job must be assigned to only one worker; it is assumed that every worker is capable of handling every job  Basic procedure of the Hungarian method:: 1) subtract the smallest number in each row from every number in the row. 2) subtract the smallest number in each column of the new table from every number in the column. 3) test whether an optimum assignment can be made. 4) *see page 702*. 5) repeat steps 3 and 4 until an optimal table is obtained. 5) make the assignments.  Sequencing – concerned with determining job processing order  Priority rules – simple heuristics used to select the order in which the jobs will be processed  Effectiveness of any given sequence is judged on performance measures, some common ones are::: 1) job flow time (amount of time it takes from when a job arrives until it is complete). 2) job lateness (amount of time the job completion date is expected to exceed the date the job was due or promised to a customer). 3) makespan (total time needed to complete a group of jobs). 4) average number of jobs (= total flow time / makespan).  The SPT rule always results in the lowest average completion time  Major disadvantage of SPT is that it tends to make long jobs wait.  The EDD rule directly addresses due dates and minimizes lateness  Johnsons rule – technique managers can use to minimize the makespan for a group of jobs to be processed on two machines/at two workcenters  Johnsons rule steps:: 1) select job with the shortest time. 2) eliminate the job and its time from further consideration. 3) repeat steps 1 and 2, working toward the center of the sequence.  Scheduling can be difficult for many reasons, one of which is that, in reality, an operation must deal with variability in setup times, processing times, interruptions, and changes in the set of jobs  Ways to minimize scheduling difficulties:: set realistic due dates, focus on bottleneck operations, consider lot splitting for large jobs  The theory of constraints (Eli Goldratt) – 1) an hour lost at a bottleneck operations is an hour lost by the system. 2) saving time through improvements of a nonbottleneck will not increase the ultimate output of the system. 3) activation of a resource is not the same as utilization of a resource.  Scheduling service systems presents certain problems because of:: 1) the inability to store or inventory services, 2) the random nature of customer requests, 3) the fact that when waiting customers can observe the service, first come first served is used even though it isn’t the most efficient.  The approach used to schedule services generally depends on whether customer contact is involved  an ideal situation is one that has a smooth flow of customers through the system, this would occur if each new customer arrives at the precise instant that the last customers service is completed  scheduling in service systems may involve scheduling 1) customers, 2) the workforce, 3) equipment

 Scheduling customers usually takes the form of appointment systems or reservation systems  Appointment systems – intended to control the timing of customer arrivals in order to minimize customer waiting while achieving a high degree of capacity utilization  Reservation systems – designed to enable service systems to formulate a fairly accurate estimate of the demand on the system for a given time period and to minimize customer disappointment generated by excessive waiting or no availability  Yield management – application of pricing strategies to allocate capacity among various categories of demand with the goal of maximizing the revenue generated by the fixed capacity  Scheduling customers is demand management, scheduling the workforce is capacity management  Generally, a basic work pattern is set and a list of staffing needs for the schedule cycle (usually one week) is given  In some situations, it is necessary to coordinate the use of more than one resource  The greater the number of resources to be scheduled simultaneously, the greater the complexity and the less likely an optimum schedule can be achieved  Scheduling can either help or hinder operations strategy.  If scheduling is done well, goods or services can be made or delivered in a timely manner, resources can be used to the best advantage, and customers will be satisfied ...