The terms planning and scheduling are often used interchangeably, but they actually refer to pretty distinct business processes. In this article we describe the goals of each process and their differences.
The planning process creates a mid term tactical plan, with the purpose of organizing material and capacity timely for the upcoming demand. The purpose of the planning process is to identify bottlenecks before they occur, and take the appropriate corrective actions (such as increasing capacity, outsourcing production, looking for alternate supplier, etc). A good planning process is essential to enhance reactivity, competitiveness, increase profits and improve customer service.
The scheduling process creates a detailed short term execution plan for individual machines, operators and materials, taking into account all constraints.
|Goals||How to execute the plan?||What, how much, when and where to produce and stock?|
|Key outputs||Purchase orders
Resource task lists
Purchasing forecast for supplier
Master production schedule
Rough cut capacity plans
|Time Horizon||Short term.
Typically 1 to 8 weeks.
Typically 3 to 12 months.
|Time granularity||Up to seconds||Weekly or monthly time buckets|
|Constraints||Modelled in detail (but can still take some abstraction from the actual execution).
Eg capacity plan for individual machines
Eg continuous capacity model: 1 job at a time on the resource
|Can be modelled at a rough, aggregate level.
Eg capacity planning by machine groups
Eg bucketized capacity model: constraint by quantity/bucket or hours/bucket
The distinction is however not black and white as there is some overlap between both. For instance, some materials can be purchased from the detailed schedule. But materials with a long lead time will need to be ordered based on the forecast established in the planning process.
FrePPLe’s functionality covers both processes. In a basic setup, a single frePPLe model is used. In complex multi-factory production environments we may have multiple models: a tactical model for the overall network planning, and a model per factory for the short term detailed scheduling.