Scheduling
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The document outlines key concepts in operations scheduling, including routing, dispatching, and prioritization within production management. It discusses methods such as forward and backward scheduling, finite and infinite loading, and the use of Gantt charts for tracking job schedules. Additionally, it addresses line balancing and strategies for managing production capacity against demand, emphasizing the associated costs and their impact on decision-making.
Scheduling
- 1. Operations Scheduling Prepared By, Mr. Nishant Agrawal METAS Adventist College (NEHU)
- 2. Routing, Prioritizing , Dispatching The operation manager designs a product according to customer requirements and decides the order of works centres or department through which the product should be processed. This is called the routing plan, specifies the route to be followed by a semi finished good from one department to another. The Operation manager must send information about the details schedule of various order to the production supervisor in the form of dispatch lists. This is called dispatching the dispatch lists. The priority or importance of each customer order for processing is another important task in scheduling. This is called prioritization.
- 3. Expediting The operation manager has to keep track of the process of various jobs. In practical situations, there are instances when there are deviations from the schedule during the implementation of jobs. This may be due to machine breakdown, delay in the delivery of raw materials, some last minutes rush orders. In such situations, the schedule may have to be revised by the manager and some jobs expedited or handles on a special priority basis. This is called expediting in scheduling terminology.
- 4. What is Scheduling ? Scheduling is a method where there is a set of x tasks which need to be completed on a set of y resources in an efficient manner. “Companies use backward and forward scheduling to allocate plant and machinery resources, plan human resources, plan production processes and purchase materials.”
- 5. Forward Scheduling Assigning customer orders or jobs to various works centres based on ‘as early as possible’ . A job is scheduled at a work centre as soon as it is free to process job. The job is then finished as soon as possible. This approach is based on the assumption that a customer is ready to receive the goods as soon as these are produced. Forward scheduling may result in jobs being completed earlier then the requested due date because forward scheduling schedules the tasks as early as possible. Forward scheduling tells you when a job could be completed
- 6. Backward Scheduling Another way of scheduling is backward scheduling, ‘as last as possible’ that jobs are finished by their due dates for delivery to the customer. The planning process starts with assigning the job to the last work centre in the processing sequence. According to the processing time of the job at the various work centres, the schedule is worked out towards the beginning of the processing sequence. This approach results on a significant reduction of work in progress / inventory Backwards scheduling requires a delivery date from the customer because the system schedules backwards from the delivery date to arrive at a start date.
- 7. Finite and Infinite Loading Loading means assigning tasks to work centres or machines. Every machine or work centre has a maximum production capacity for a normal working day. Finite loading involves assigning tasks to work centres such that the maximum capacity of the work centre is not exceeded at any time. Infinite loading means overlooking the maximum capacity of machine or work center while assigning task to it. Machine beyond its maximum capacity of eight working hours per day. Operations manager knows that the excess work scheduled during some time periods can be shifted to other work centres or time periods.
- 8. Schedule Gantt Chart A Gantt chart is a type of bar chart, devised by Henry Gantt in the 1910s, that illustrates a project schedule Show the job schedule on a timescale. This representation of jobs in Gantt Chart helps the operations manager to track the process of various jobs at any point if time. This chart is also used in information technology to represent data that has been collected. Gantt charts can be used for scheduling generic resources as well as for their use in project management. They can also be used for scheduling production processes
- 10. Line balancing Line balancing is the process of assigning tasks to workstations, so that workstations have approximately equal time requirements. We use line balancing to : minimize idle time. balance bottlenecks. This is an analysis process which tries to equally divide work to be carried out in a production process among workstations. In production line workstations and work centers are arranged in a sequence of task to be done along a straight or curved line.
- 11. Continue… Line Of Balance (LOB) is a management control process for collecting, measuring and presenting facts relating to time, cost and accomplishment - all measured against a specific plan. It shows the process, status, background, timing and phasing of the project activities, thus providing management with measuring tools that help: Comparing actual progress with a formal objective plan. Examining only the deviations from established plans Receiving timely information concerning trouble areas and indicating areas where appropriate corrective action is required. Forecasting future performance.
- 12. GOAL AND OBJECTIVE Goal of production line analysis: Number of workstations needed. Type of task should be assigned to each workstation. To know the minimum number of workers, tools and machines that can be used to provide the required amount of capacity. Objective of line balancing: Assigning task to each workstation in such a way that there is only a little idle time.
- 13. LINE BALANCING PROCEDURE 1. Determination of tasks that must be performed to complete one unit of a product. 2. Determining the order or sequence of performing the whole set of tasks. 3. Drawing precedence diagram. In this flowchart circles represents task and joining arrows represents precedence. 4. Estimation of task time. 5. Calculation of cycle time. 6. Determination of minimum number of workstation required. 7. Using one of the heuristics / method to assign tasks to workstations for balancing production line.
- 14. Strategies and Costs In trying to meet the demand with the production capacity in the intermediate range we have the following different strategies at hand. 1. Overtime and under time 2. Hiring and layoff , single or multiple shifts 3. Carrying inventories to meet the peak demand 4. Having backlog of order 5. Sub contracting to other companies 6. Turning down some sales demands
- 15. Continue… Each of these strategies has a cost factor associated with it. The marginal cost of overtime is not difficult to estimate whereas the costs of under time are not that easy to determine. The hiring costs include the costs of selection, he costs of training and the cost of maintaining additional records. There are costs associated with learning on the job of newly hired employee. The costs of inventory include the capital cost for carrying the inventory, the cost of obsolescence, taxes and insurance etc. The stock out costs are the costs due to lost sale or the loss of goodwill of the customer. The combination rather than a single strategy will usually result in the most economical plan.’