OVERVIEW OF PRODUCTION SCHEDULING
Production scheduling is the allocation of resources and the sequencing of tasks to produce goods and services. Production scheduling specifies the time each job starts and completes on each machine.
- Production scheduling is the process of arranging, controlling and optimizing work and workloads.
- It is used to allocate plant and machinery resources, plan human resources, plan production process and purchase materials.
- It determines when an operation is to be performed, or when work is to be completed; the difference lies in the detail of the scheduling procedure.
- It is a project plan of how the production budget will be spent over a given time scale, for very phase of a business project.
- It integrates the people, machine, materials, customer demands and quality requirements in finalizing the priorities. Scheduling makes it possible by determining starting and completion data each of the operations.
- In a centralized control situation – where all process planning, loading, and scheduling for the plant are done in a central office- the details of the schedule may specify the starting and finishing time for an operation.
- Thus, scheduling is the last stage of planning before production starts.
OBJECTIVES OF PRODUCTION SCHEDULING:
- Meet customer due dates.
- Minimize job lateness.
- Minimize response time.
- Minimize completion time.
- Minimize time in system.
- Minimize overtime.
- Maximize machine on labor utilization.
- Minimize idle time.
- Minimize work in process inventory.
LOADING- CONCEPT AND TYPE OF LOADING:
- Once the route has been established, the work required can be loaded against the selected machine or workstation.
- The total time required to perform the operation is computed by multiplying the unit operation times given on the standard process sheet by the number of parts to be processed.
- This total time is then added to the work already planned for the workstation.
- This is the function of loading, and it results in a tabulated list or chart showing the planned utilization of the machines or workstations in the plant.
- Loading involves assigning jobs to work centers to various machines in the work centers.
- If a job can be processed on only one machine, no difficulty is presented. However, if a job can be loaded on multiple work centers or machines and there are multiple jobs to process, the assignment process becomes more complicated.
TYPES OF LOADING
(a) Infinite Loading (b) Finite Loading
(a) INFINITE LOADING:
- With infinite loading jobs are assigned to work centers without regard for capacity of the work center.
- Ignores capacity constraints, but helps identify bottlenecks in a proposed schedule to enable proactive management.
- Jobs are loaded at work centers according to the chosen priority rule.
- Priority rules are appropriate for use under the infinite loading approach.
ADVANTAGE- Consumes less time in assigning the job to work centers as analysis of capacity of work centers is not required.
DISADVANTAGE– Job may not be accomplished with efficiency as job can get assigned to work centers with less capacity than what is required.
(b) FINITE LOADING:
- Allows only as much work to be assigned as can be done with available capacity – but doesn’t prepare for inevitable slippage.
- Finite loading considers the capacity of each work center and compares the processing time so that process time does not exceed capacity.
- With finite loading the scheduler loads the job that has the highest priority on all work centers it will require.
- Then the job with the next highest priority is loaded on all required work centers, and so on.
ADVANTAGE– Job can be accomplished with efficiency as job gets assigned to work centers based on the capacity they have.
DISADVANTAGE– Consumes more time in assigning the job to work centers as analysis of capacity of work centers is required.
Companies benefit from both infinite and finite loading. Infinite loading identifies bottlenecks of resource availability and finite loading develops the operational scheduling that uses the available capacity. Both techniques use either a schedule (infinite) or prioritized list of jobs to be done (finite).