Advanced Planning and Scheduling
Historical Planning and Scheduling
The goal of any manufacturing enterprise is to generate a profit. In order to generate a profit, the enterprise invests in productive assets and attempts to employ these assets in the most efficient manner possible, while satisfying the needs of its customers. These assets might include capital equipment, tooling, labor, and material.
In the short term, the process of efficiently employing assets historically has been known as production scheduling. This involves placing work on resources in a particular order. In the longer term, the process of efficiently employing assets has historically been known as production planning. This involves loading hours on resources, and subjecting the load to a capacity planning process to spot imbalances.
An Integrated Planning and Scheduling Approach
Dividing planning and scheduling into different approaches depending upon time frame is artificial and is based on historical limitations in tools that no longer apply. In the real world, the planning and scheduling process involves the myriad of decisions that must be made short to long term. The diagram below outlines some of these planning and scheduling decisions that must be made by various groups within the manufacturing enterprise.
The operations group takes in orders which will fluctuate in terms of quantity, mix and priority. In the short term, it has the responsibility of judiciously managing existing capacity so that delivery requirements are met. To perform this task, the operations group must determine the sequence or priority that orders will run, the dates that production will commence, and the quantities that will be produced.
The operations group is also responsible for planning and scheduling around the problems that can rob the operation of its available capacity. These problems include new orders, order changes, material shortages, breakdowns, labor problems, vendor problems, and quality problems.
The operations group is influenced by the policy constraints set by the management group. These constraints are termed “soft” because they can be varied in the short term. The operations group is also influenced by the constraints set by the engineering group. These constraints are termed “hard” because they are typically fixed in the short term.
The management group determines what kinds of lead times will be quoted, inventory levels, overtime and other labor policies, and sets the general guidelines that influence how the operation’s shop floor is run. They use market information and feedback on performance in setting these policies. All these policies influence the planning and scheduling of available capacity and therefore delivery.
The engineering group determines the levels of machinery, tooling, and equipment that will be available to the operations group for the purpose of planning and scheduling. They build and maintain the standards and routings that determine how product flows through the plant and also control the plant processes. The engineering group typically certifies vendors and determines to whom work can be outsourced.
Need for Advanced Planning and Scheduling Software
The key to better planning and scheduling is visibility. Changing conditions require that the plans of management, engineering and operations be constantly modified. Every modification and accompanying action has a cost and a result. Increased visibility helps companies predict, with greater certainty, the costs and results of their actions, thus ensuring that the best decisions are made.
In today’s complex and dynamic manufacturing plants, this visibility is almost impossible to obtain manually. For instance, no company or vendor has the time to manually calculate the amount of capacity for production requirement and the effect on delivery of multiple requirements competing for limited capacity. No company or vendor has the time to factor in all unforeseen events affecting available capacity or to consider multiple alternatives to improve delivery.
In order to gain this planning and scheduling visibility, companies have increasingly been turning to software tools, specifically Finite Capacity Scheduling software and Advanced Planning and Scheduling software.