By allocating resources, planning the order of events and determining processes required for creating goods and services, few functions within manufacturing companies are as crucial as a production schedule.
Without one, today’s complex production environments would at best be wasteful and haphazard. And at worst, the lack of one could cause the operation to grind to a halt.
Traditionally, production schedules were thought of as a necessary evil, an overhead function consisting of lists and matrices (and later spreadsheets) to provide the manufacturing departments with a general timeframe and path for production.
But with increasing sophistication in manufacturing methods and the software available to manage production in a more precise manner and with the increasing complexity of global supply chains, production schedules are more important than ever.
With a well-defined production schedule based on accurate data inputs, a manufacturer can balance the requirements resulting from the order position with the available resources to make goods and services to meet orders.
Accurate production schedules can also be changed and adjusted to address temporary shifts in production requirements caused by seasonality, rapidly evolving consumer tastes and other disruptions.
In production scheduling, the role of planning is to utilize the company’s resources to maintain a consistent production flow. By doing so, downtime is reduced, and bottlenecks are mitigated to optimize production. Two types of planning that can used for production scheduling:
Examples: An example of a company that would utilize static planning would be one that produces breakfast cereal. Here, sales history, past growth levels and new rollouts can help determine the production level for the year so that it is consistent and reliable.
An example of dynamic planning would be a company that produces custom orthodontics. In this case, the company would have materials, equipment and staff on hand for a predicted flow of orders, but production plans would not be completed until orders are received as each order is a custom build.
In discreet manufacturing where final products are made from a lengthy and complex series of sub-processes, a bill of materials may be used to dictate what items are required and in what quantity.
The routing maps the flow of required process steps and decides the path and sequence of performed operations. It may include steps that must be done in-house but can also include components that may need to be sub-contracted and then returned to the production flow for final assembly.
Examples of manufacturing that requires routing would be a textile manufacturer which must spin the yarn to make thread to be woven in both directions and then woven, finished, and died with specific dye formulations.
An example of a company that utilizes a routing with sub-contracting would be a medical cart manufacturer which requires bending of tubes and pipes to be used in the assembly of the cart but where the pipes need to be sent to a coating sub-contractor to apply a chrome finish before final assembly.
Scheduling utilizes the established planning level to produce goods from components or raw materials. It is time based and must satisfy the demand established at the planning level.
These time tables can be department specific, product specific and process specific. Master production schedules are used at the highest level defining the product timeframes while sub-schedules may be department specific for sub-assemblies or for mixes and blends.
An example of a schedule is one for a tissue factory, where the schedule includes the production of the tissue fibers into raw tissue form within a specific time with additional time allotted for cutting, internal packaging, boxing and even for skidding of a specific product count based on retailer requirements.
Each process or series of processes has a time to complete that utilizes a routing that is based on planning to be completed according to the schedule.
Dispatching is the process of assigning the order of jobs to be done next from a sub-set of jobs in the production queue. Dispatching is used to make decisions for immediate action. This is different in comparison to planning where decisions are determined for future actions. Dispatching is used in both pull and push production systems.
An example of dispatching can be found in a company that manufactures ceiling fans. If the production line is producing white five blade fans with no lights attached, and the next job is to produce brown fans with no lights, dispatching may dictate that the third job to follow be for production of brown fans with lights so that the blades and housing in the appropriate color will already be staged at the workstation and all that need be included are the lighting components.
Production scheduling must rely on proper execution to ensure that all processes are done correctly and in the order they are intended to be produced.
It requires that everyone knows what they are supposed to do and when they are supposed to do it. Execution requires informed management decisions, trained staff, accurate data as inputs into the production plan and schedule and reliable sales figures and forecast numbers. All must be present for the organization to execute its production schedule and complete orders.
An example of execution would be a manufacturer who produces appliances where seasonal holiday demands create numerous disruptions. Sales staff and managers must work to provide accurate inputs into the system and must understand when, how and where to shift production as one model or brand takes off while another may lag behind. Proper execution would mean that the fewest bottlenecks occur as the production plan, routings and dispatching are done in an agile fashion to optimize the schedule.
Production scheduling is an important part of any manufacturing process. This is true for discrete manufacturing, process manufacturing or assembly companies. By understanding the importance of each component, schedulers can come up with a checklist to ensure that all processes occur at the right time and in the right sequence to produce at the most cost-effective level.